Professor Ho Kyong Shon is an Australia Research Council (ARC) Future Fellow, President of the Membrane Society of Australasia (MSA), Editor for the Journal of Desalination, and Deputy Director of Center for Technology in Water and Wastewater. He specializes in understanding physico-chemical water treatment processes in water, wastewater and seawater. His research career focuses on studying advanced membrane fabrication and the application of membrane based desalination in detailing membrane fouling mechanisms and developing novel desalination technology.
He has co-authored over 350 high-impact refereed journal publications (51 h-index and > 9900 total citations) including five patents and numerous international awards over the last 16 years.
He is currently supervising several postdoctoral research fellows, ten PhD students and two Masters students related to membrane and nanotechnology for water purification.
- UTS Vice-Chancellor's Research Excellence Award by Collaboration and Partnership, 2019
- Editor of the Journal of Desalination 2019 - present
- President of Membrane Society of Austrlasia (MSA) 2018 - present
- Vice President of Aseanian Membrane Society (AMS) 2018 - present
- Vice President/Diector of Membrane Society of Australasia (MSA) 2015- 2018
- Deputy Director of Center for Technology in Water and Wastewater 2009 - present
- ARC Future Fellow 2015–2019
- Early Career Research Excellence Category 2013 UTS Vice-Chancellor’s Award (Winner)
- Innovation award 2013 FEIT Showcase, UTS
- First Prize in Poster presentation 2013 – International Conference on Advanced Nanocomposite for construction Materials
- Novel Technology Award 2012 5th International Desalination Workshop (IDW 2012)
- Early Career Research Excellence Category 2012 UTS Vice-Chancellor’s Award (Finalist)
- Best Paper Presentation 2012 International Conference in Challenges in Environmental Science and Engineering (CESE2012)
- Global Honour of the 2012 IWA Project Innovation Awards (PIA) 2012 International Water association
- Winner of the 2012 IWA Project Innovation Awards (PIA), Asia Pacific Regional Awards 2012
- International Water Association
- Partnership Research Excellence Category 2011 UTS Vice-Chancellor’s Award (Finalist)
- Early Career Research Excellence Category 2010 UTS Vice-Chancellor’s Award (Finalist)
- Project Innovation Awards 2010 The 2010 IWA Asia Pacific Regional Project Innovation Awards (Honour Award in Applied Research)
- Best Poster Presentation Award 2008 2008 International Conference on Nanoscience and Nano Technology, Chonnam National University
- Chancellor’s Thesis Award from across University for 2006 University of Technology, Sydney (UTS)
- Water Environment Merit Award (WEMA) 2006 NSW Branch of Australian Water Association (AWA)
- Best Student Paper 2005
- International Congress on Membranes and Membrane Processes (ICOM2005) Best Presented Paper 2004
- Showcase, Faculty of Engineering, University of Technology, Sydney (UTS)
- Full PhD Scholarship 2002-2005 Kwanjeong Education Foundation, The Republic of Korea
- Best Presented Paper 2002 Korean Society of Environmental Engineers
- Brain Korea 21st Master Scholarship 2000–2002 Myongji University
- Editor in Desalination
- Editor in Water Science and Technology (IWA publishing)
- Associate Editor in Process Safety and Environmental Protection (Elsevier)
- Guest Editor in Desalination and Water Treatment (Balaban publication)
Conference Committee Member
- International conference on the “Challenges in Environmental Science & Engineering”
- The International Membrane Science and Technology Conference (IMSTEC)
- International Desalination Workshop
- International Water Association
- Australia Water Association
- Membrane Society of Australasia
- American Society of Civil Engineers
- Indian Membrane Society
Can supervise: YES
- Membrane technologies
- Resource recovery
- Wastewater treatment and reuse technologies
- Advanced oxidation processes
- Nanoparticle for water purification
Summary of my area of expertise
Professor Ho Kyong Shon has internationally recognized expertise in the field of desalination and water reuse. Dr Shon has in particular made significant contributions in terms of novel process development, membrane fabrication, membrane hybrid systems and new coagulant for water purification.
Low-energy and low-cost fertilizer forward osmosis (FDFO) and its membrane fabrication for desalination
Drought and water scarcity are common in Australia and desalination is increasingly sought to augment fresh water supplies to meet the growing water demand. Although, the cost of reverse osmosis based desalination has substantially reduced, this method of desalination still remains energy intensive (4 kWh/m3). Dr Shon’s research, funded by National Centre of Excellence in Desalination Australia (NCEDA) and the Australia Research Council (ARC), has been aimed at making desalination more sustainable by reducing its energy demands. It has led to the development of a novel low-energy FDFO desalination process and forward osmosis membrane fabrication using electrospinning.
Development of FDFO pilot scale desalination funded by NCEDA
Forward osmosis is an emerging and novel desalination technology with significantly lower energy costs than conventional technology. As yet there has been no large-scale application of forward osmosis because of the lack of a suitable draw solution that can be easily recovered with minimum energy. Dr Shon’s research evaluated the potential of various forms of fertilisers for use as forward osmosis draw solute and then optimised the process parameters for desalination of brackish groundwater ultimately leading to the design of a pilot scale forward osmosis desalination unit for fertigation application.
It is anticipated that such technology could be suitably applied in the Murray-Darling basin to convert brackish groundwater into nutrient rich irrigation water with minimum energy. The concept is that the forward osmosis desalination process could be integrated with the existing salt interception scheme in the basin where brackish groundwater is pumped out and simply lost through evaporation. Such a desalination scheme is expected to have a significant impact on agriculture in the drought prone areas of Australia through sustainable use of brackish groundwater.
A concentrated solution of fertilisers was used as osmotic agent (draw solution) and brackish water as feed water. The process is not significantly different from the conventional forward osmosis desalination process except that it excludes a draw solution recovery process, which significantly saves energy cost. The process consists of a forward osmosis membrane unit with one face connected to the feed water and the other face connected to the draw solution. The draw solution in this particular case consists of only soluble fertiliser which after extraction of water can be used directly for fertigation with or without the need of further dilution. Water is extracted from the saline water (feed water) due to high osmotic gradient between the concentrated fertiliser draw solution and the feed solution. The only energy used in this process is for running the two pumps which do not exert any hydraulic pressure.
This design concept for a novel, low-energy FDFO desalination process was developed by Dr. Shon’s team in collaboration with NSW State Water, CSIRO, Korea University and Yale University through two projects funded by NCEDA. The first project focussed on fundamentals of FDFO process and its success precipitated an invitation to apply for an accelerated proposal for designing and fabricating a FDFO pilot scale desalination unit with a capacity of about 1 m3/day. Testing of the pilot scale scheme is in progress.
In addition to the design and fabrication of the pilot scale scheme, Dr. Shon’s research in this FDFO area has achieved: (i) 8 high-impact journal publications since 2011 (one of the papers published in 2011 has been already cited more than 100 times); (ii) an invitation by the American Society of Civil Engineers (ASCE) to organise the first forward osmosis book as a chief editor: “Forward Osmosis Process: Fundamentals & Applications” in recognition of the quality of his achievements in this area; (iii) successful training of five postgraduate students and one postdoctoral research fellow (one PhD and two Masters students already completed their theses) and (iv) two awards - the Novel Technology Award, International Desalination and workshop (IDW) in 2012 and an Innovation award, UTS Faculty showcase in 2013.
Novel forward osmosis membrane development
Dr Shon has recently been awarded an ARC to commence. This project is aimed at developing very thin and mechanically robust forward osmosis membrane with high performance for FDFO application. This uses two approaches to reducing the membrane structural thickness, both employing electrospun nanofiber. The first approach is termed as paired design support layer that involves using electrospun nanofiber as backing layer instead of traditional polymer fabrics. The use of electrospun nanofiber as backing layer significantly reduces the thickness of the backing layer. The traditional polymer backing layer used in the synthesis of thin film composite membrane provides additional membrane support thickness by more than 100 µm which can significantly contribute towards concentration polarisation effects. By selecting a suitable material, the thickness of the backing layer can be significantly reduced without compromising the mechanical strength. The second approach involves completely removing the polymer cast-mid layer and using only electrospun nanofiber as support layer for the rejection layer. This approach produces the thinnest membrane support layer with the removal of the cast-mid layer.
This research in fabricating a new generation of forward osmosis membrane and developing novel process will be an opportunity to work closely with other researchers at UTS including distinguished visiting scholars to UTS from all over the world. Generating nanofibrous forward osmosis membrane and low energy FDFO desalination process is a novel and new approach and this research demonstrates how Dr Shon should embark research on cutting-edge technologies. Dr Shon has collaborated with overseas leading researchers related to forward osmosis technology in USA, Singapore and Korea and he is currently negotiating with numerous industries such as Centennial Coal, Samsung in Korea, CSM membranes in Korea and Toyobo in Japan to open the commercial opportunities.
Novel membrane distillation membrane development
Dr Shon is actively developing membrane distillation membrane using electrospining for desalination. The main aim of this research is to synthesize and develop a membrane with engineered properties to overcome these two major limitations and enhance the efficiency of membrane distillation process ultimately increasing the commercialization prospects of MD technology. This project involves engineering and improving the design and properties of the membrane structure by developing a superhydrophobic and highly-porous membrane using multi-component and functionalized nanofibrous layers. The specific aims of this project are to develop a novel, next-generation high performance superhydrophobic membrane with engineered and improved surface and structural properties using electrospun nanofibrous functionalized membrane layers and to conduct fundamental studies and experimental verification of the influences of the improved surface, structural and functional properties of the membrane and develop modified predictive models for water flux in the membrane distillation process using RO brine .
By using the different electrospinning configurations, we can fabricate highly hydrophobic membranes with high porosity, however, it is also deemed necessary that the mechanical integrity of the membrane is considered, thus we propose to adopt the following innovative techniques:
- By using a functionally-graded nanofibrous membrane structure with varying pore sizes. The advantage of this configuration is the fabrication of highly porous structure at the feed side and bigger fiber pores and fiber diameter in the permeate side providing enhanced mechanical strength of the membrane structure.
- By using multi-component nanofibrous support layer. Multi-spinneret electrospinning could be an excellent method to fabricate hybrid materials containing mixed properties of each component polymer.
- Incorporation of nanoparticles in the electrospun nanofibrous support layer that can enhance the mechanical strength of the membrane and provide functionality. For example, adding carbon nanotubes in polyurethane nanofiber enhanced the mechanical properties of the composite nanofiber and provided higher hydrophobicity due to the presence of hydrophobic carbon nanotubes on the surface. In our previous study, when compared with PU film, PU nanofiber exhibited higher hydrophobicity due to increased surface roughness as well as the presence of carbon nanotube.
- By heat-pressing of nanofibrous membrane to increase its mechanical properties.
Titanfloc coagulation for innovative water purification
Since 2005, Dr Shon has explored a novel titanium coagulant development to generate TiO2 from Ti-salt coagulated sludge and its application of photocatalysis using photoreactive TiO2 nanomaterials for water purification. This research uses a novel coagulant of titanium tetrachloride (TiCl4) instead of more commonly used salts of iron (FeCl3) and aluminum (Al2(SO4)3) to remove particulate and dissolved organic matter from the wastewater in sewage treatment plants (STPs). Titanium tetrachloride (TiCl4) successfully removed organic matter to the same extent as Fe and Al salts. The settling of Ti sludge was faster which made the subsequent separation process easier. After flocculation with titanium salt, the settled floc (sludge) was calcined to produce functional titanium dioxide (TiO2) nanomaterials, which have the same quality as that of commercial TiO2. Thus, the use of Ti salt instead of Fe or Al salts is more efficient and can recover a byproduct of functional TiO2 nanomaterials of 450 kg/day from a medium size STP of 25 ML/d. The cost of TiCl4 is not high and similar to that of Al and Fe salts. This process will be efficient and economical not only in terms of removal of organic matter, but also in sludge reduction and wastewater reuse and produces a viable commercial product. The amount of TiO2 nanomaterials recovered by this process from STPs meet the demand of TiO2 used in major applications of TiO2 photocatalysis such as pigments, paper, solar cells and environmental applications for the degradation of waste and for hydrogen generation by photocatalytic water-splitting. Sludge disposal is one of the most costly and environmentally problematic challenges of modern wastewater treatment worldwide. In this research, Dr Shon’s contribution could significantly lower the cost of waste disposal, protect the environment and public health and yield economically useful by-product TiO2. Therefore this research has high potential impacts of scientific innovation and environmental and economic benefits.
This novel processes which are fully patented by UTS. This research concept was awarded several prestigious awards: i) Global Honour Award of the 2012 IWA Project Innovation Awards, ii) Winner of the 2012 IWA Project Innovation Awards, Asia Pacific Regional Awards 2012, iii) Water Environment Merit Award (WEMA) 2006, NSW Branch of Australian Water Association (AWA).
- The Executive of Memrane Socieity of Australasia
- Council Member of Aseanian Membrane Society
- School Research Commitee, 2016–present
- Faculty Board Member at UTS 2013–2015
- Course coordinator in Civil and Environmental Engineering 2012–2014
- Advanced Water and Wastewater Treatment 2014–present
- Environmental Chemical Processes
- Water and Environmental Design 2012–2014
- Fluid Mechanics 2012–2014
- FEIT library Committee 2009–present
- Research seminar coordinator in Civil and Environmental Engineering 2007–2014
- Pollution control and Waste management 2011–2012
- Wastewater engineering (College of Technical And Further Education (TAFE) 2009
- Water storage and supply (College of Technical And Further Education (TAFE) 2008
- Introduction to Civil and Environmental Engineering 2008–2014
- Water Supply and Wastewater Engineering 2007
- Water Quality modelling on organic characterisation at UTS (49113) 2007
- Waste and Pollution at UTS (49123) 2007
- Environmental analysis 2000–2002
- Advanced Mathematics 2000–2002
Hossain, SM, Park, H, Kang, HJ, Kim, JB, Tijing, L, Rhee, I, Jun, YS, Shon, HK & Kim, JH 2020, 'Preparation and characterization of photoactive anatase TiO2 from algae bloomed surface water', Catalysts, vol. 10, no. 4.View/Download from: Publisher's site
© 2020 by the authors. Licensee MDPI, Basel, Switzerland. The purpose of the study was to effectively treat algae bloomed water while using a Ti-based coagulant (TiCl4) and recover photoactive novel anatase TiO2 from the flocculated sludge. Conventional jar tests were conducted in order to evaluate the coagulation efficiency, and TiCl4 was found superior compared to commercially available poly aluminum chloride (PAC). At a dose of 0.3 g Ti/L, the removal rate of turbidity, chemical oxygen demand (COD), and total phosphorus (TP) were measured as 99.8%, 66.7%, and 96.9%, respectively. Besides, TiO2 nanoparticles (NPs) were recovered from the flocculated sludge and scanning electron microscope (SEM), energy dispersive X-ray spectroscope (EDX), and X-ray diffraction (XRD) analysis confirmed the presence of only anatase phase. The recovered TiO2 was found to be effective in removing gaseous CH3CHO and NOx under UV-A lamp at a light intensity of 10 W/m2. Additionally, the TiO2 mixed mortar blocks that were prepared in this study successfully removed atmospheric nitrogen oxide (NOx) under UV irradiance. This study is one of the first to prepare anatase TiO2 from flocculated algal sludge and it showed promising results. Further research on this novel TiO2 concerning internal chemical bonds and shift in the absorbance spectrum could explore several practical implications.
Lee, D, Woo, YC, Park, KH, Phuntsho, S, Tijing, LD, Yao, M, Shim, WG & Shon, HK 2020, 'Polyvinylidene fluoride phase design by two-dimensional boron nitride enables enhanced performance and stability for seawater desalination', Journal of Membrane Science, vol. 598.View/Download from: Publisher's site
© 2019 The instability of polyvinylidene fluoride (PVDF) membranes in membrane distillation (MD) for seawater desalination is still a problem, despite the tremendous effort expended to resolve this issue. Here, a simple and feasible approach for improving desalination performance through the incorporation of two-dimensional boron nitride nanosheets (BNNSs) in polyvinylidene fluoride-co-hexafluoropropene (PVDF-co-HFP) electrospun nanofiber membrane (BNs-PH) is proposed as well as demonstrate its origin for fundamental understanding. The BNs-PH membrane exhibits a stable water vapor flux (18 LMH) and superior salt rejection (99.99%), even after operation for 280 h (commercial PVDF: steep decay within 28 h; neat PH: wetting within 4 h). From structural/chemical analyses, the BNNSs play a crucial role in forming favorable phases of the PH polymer crystal structure, inducing a superhydrophobic surface with greater nanoporosity and higher heterogeneity as well as enhanced mechanical properties (increase of UTS: 13.4%; modulus: 1.2%) for long-term operation. Theoretical modeling results of an air-gap MD system are consistent with our experimental results. The approach introduced in this study can be applied to other desalination systems to boost various water treatment applications.
Tijing, LD, Dizon, JRC, Ibrahim, I, Nisay, ARN, Shon, HK & Advincula, RC 2020, '3D printing for membrane separation, desalination and water treatment', Applied Materials Today, vol. 18, pp. 1-22.View/Download from: Publisher's site
© 2019 Elsevier Ltd Additive manufacturing or commonly known as 3D printing is driving innovation in many industries and academic research including the water resource sector. The capability of 3D printing to fabricate complex objects in a fast and cost-effective manner makes it highly desirable over conventional manufacturing processes. Recent years have seen a rapid increase in research using 3D printing for membrane separation, desalination and water purification applications, potentially revolutionizing this field. This review focuses on recent advancements in 3D-printed materials and methods for water-related applications including developments in module spacers, novel filtration and desalination membranes, adsorbents, water remediation, solar steam generation materials, catalysis, etc. The emergence of new 3D printers with higher printing resolution, better efficiency, faster speed, and wider material applicability has garnered more interest and can potentially reshape research and development in this field. The promising potential, challenges and future prospects of 3D printing, additive manufacturing, and materials for water resource and treatment-related applications are all discussed in this review.
Yao, M, Tijing, LD, Naidu, G, Kim, S-H, Matsuyama, H, Fane, AG & Shon, HK 2020, 'A review of membrane wettability for the treatment of saline water deploying membrane distillation', DESALINATION, vol. 479.View/Download from: Publisher's site
Akther, N, Yuan, Z, Chen, Y, Lim, S, Phuntsho, S, Ghaffour, N, Matsuyama, H & Shon, H 2020, 'Influence of graphene oxide lateral size on the properties and performances of forward osmosis membrane', Desalination, vol. 484.View/Download from: Publisher's site
© 2020 Elsevier B.V. Graphene oxide (GO) has been widely explored for the improvement of thin-film composite (TFC) membrane performance. However, the influences of GO flake lateral size on the polyamide (PA) TFC membrane properties and performances have not been investigated. In this study, GO suspensions with an average flake size ranging from 0.01 to 1.06 μm2 were prepared by varying the sonication duration between 0 and 8 h. The different sized GO flakes were embedded in the PA layer to examine the effect of their size on the morphology and performances of TFC forward osmosis (FO) membranes. The specific reverse solute flux and water flux of the GO-modified thin-film nanocomposite (TFN) membranes improved by over 60% and 50%, respectively, when the average GO flake size was reduced from 1.06 to 0.01 μm2 due to the formation of a thinner and more uniform PA layer. Large GO flakes deteriorated membrane performance by creating impervious regions that obstructed the reaction between monomers during the interfacial polymerization process resulting in defective PA layer formation. Whereas, smaller GO flakes distributed more uniformly in the PA layer creating fewer defects, and demonstrated better desalination performance and antifouling property than the TFN membranes modified with larger GO flakes. These results deliver strategies for future improvements in GO or 2D nanomaterial-based TFN membranes, where smaller flake size can be beneficial for minimizing PA layer defects.
Dorji, P, Kim, DI, Hong, S, Phuntsho, S & Shon, HK 2020, 'Pilot-scale membrane capacitive deionisation for effective bromide removal and high water recovery in seawater desalination', DESALINATION, vol. 479.View/Download from: Publisher's site
Fang, C, Rajabzadeh, S, Zhang, P, Liu, W, Kato, N, Shon, HK & Matsuyama, H 2020, 'Controlling spherulitic structures at surface and sub-layer of hollow fiber membranes prepared using nucleation agents via triple-orifice spinneret in TIPS process', Journal of Membrane Science, vol. 609, pp. 118229-118229.View/Download from: Publisher's site
Kim, DI, Gonzales, RR, Dorji, P, Gwak, G, Phuntsho, S, Hong, S & Shon, H 2020, 'Efficient recovery of nitrate from municipal wastewater via MCDI using anion-exchange polymer coated electrode embedded with nitrate selective resin', DESALINATION, vol. 484.View/Download from: Publisher's site
Lim, S, Akther, N, Tran, VH, Bae, TH, Phuntsho, S, Merenda, A, Dumée, LF & Shon, HK 2020, 'Covalent organic framework incorporated outer-selective hollow fiber thin-film nanocomposite membranes for osmotically driven desalination', Desalination, vol. 485.View/Download from: Publisher's site
© 2020 Elsevier B.V. In this study, new outer-selective hollow fiber (OSHF) thin film nanocomposite (TFN) forward osmosis (FO) membranes incorporated with amine-rich Schiff-based network (SNW-1) nanoparticles (NPs), a type of covalent organic frameworks (COFs), were developed by vacuum-assisted interfacial polymerization (VAIP). The SNW-1 NPs possess hydrophilic nature and porous internal structures, which are desirable for producing highly permeable and efficient FO membranes. SNW-1 NPs were conformally packed across the outer surface of the HF substrate by vacuum pressure applied during the VAIP process leading to defect-free coatings. Furthermore, covalent bonding between secondary amine (NH2−) groups across the SNW-1 network and remanent carboxylic groups present from the monomer used for the interfacial polymerization step supported the adhesion of SNW-1 NPs to the native poly(amide) layer present across the TFN membrane surface. As a result, SNW-1 loading at 0.001 wt% exhibited the best FO performance with enhanced water flux more than 23% of the pristine one (31.5 L m−2 h−1) and relatively low specific reverse solute flux (SRSF, Js/Jw) at 0.18 g L−1 using 1 M NaCl and DI water in series of TFN composite membranes. The optimum loading at 0.001 wt% was much lower than those in other home-made TFN membranes (normally above 0.05 wt%) due to the minimum loss of SNW-1 in the VAIP. Also, the TFN membrane offered excellent FO operation stability tested for 72 h. Such novel approach is promising to optimize FO processes for desalination and water treatment in the future.
Lim, S, Park, KH, Tran, VH, Akther, N, Phuntsho, S, Choi, JY & Shon, HK 2020, 'Size-controlled graphene oxide for highly permeable and fouling-resistant outer-selective hollow fiber thin-film composite membranes for forward osmosis', Journal of Membrane Science, vol. 609, pp. 118171-118171.View/Download from: Publisher's site
Liyanaarachchi, S, Jegatheesan, V, Shu, L, Shon, HK, Muthukumaran, S & Li, CQ 2020, 'Evaluating the Feasibility of Forward Osmosis in Diluting RO Concentrate Using Pretreatment Backwash Water.', Membranes, vol. 10, no. 3.View/Download from: Publisher's site
Forward osmosis (FO) is an excellent membrane process to dilute seawater (SW) reverse osmosis (RO) concentrate for either to increase the water recovery or for safe disposal. However, the low fluxes through FO membranes as well the biofouling/scaling of FO membranes are bottlenecks of this process requiring larger membrane area and membranes with anti-fouling properties. This study evaluates the performance of hollow fibre and flat sheet membranes with respect to flux and biofouling. Ferric hydroxide sludge was used as impaired water mimicking the backwash water of a filter that is generally employed as pretreatment in a SWRO plant and RO concentrate was used as draw solution for the studies. Synthetic salts are also used as draw solutions to compare the flux produced. The study found that cellulose triacetate (CTA) flat sheet FO membrane produced higher flux (3-6 L m-2 h-1) compared to that produced by polyamide (PA) hollow fibre FO membrane (less than 2.5 L m-2 h-1) under the same experimental conditions. Therefore, long-term studies conducted on the flat sheet FO membranes showed that fouling due to ferric hydroxide sludge did not allow the water flux to increase more than 3.15 L m-2 h-1.
Nuruzzaman, M, Ren, J, Liu, Y, Rahman, MM, Shon, HK & Naidu, R 2020, 'Hollow Porous Silica Nanosphere with Single Large Pore Opening for Pesticide Loading and Delivery', ACS APPLIED NANO MATERIALS, vol. 3, no. 1, pp. 105-113.View/Download from: Publisher's site
Phuntsho, S, Kim, JE, Tran, VH, Tahara, S, Uehara, N, Maruko, N, Matsuno, H, Lim, S & Shon, HK 2020, 'Free-standing, thin-film, symmetric membranes: Next-generation membranes for engineered osmosis', Journal of Membrane Science, vol. 607, pp. 118145-118145.View/Download from: Publisher's site
Van, HT, Lim, S, Park, MJ, Han, DS, Phuntsho, S, Park, H, Matsuyama, H & Shon, HK 2020, 'Fouling and performance of outer selective hollow fiber membrane in osmotic membrane bioreactor: Cross flow and air scouring effects', BIORESOURCE TECHNOLOGY, vol. 295.View/Download from: Publisher's site
Pathak, N, Phuntsho, S, Van, HT, Johir, MAH, Ghaffour, N, Leiknes, T, Fujioka, T & Shon, HK 2020, 'Simultaneous nitrification-denitrification using baffled osmotic membrane bioreactor-microfiltration hybrid system at different oxic-anoxic conditions for wastewater treatment', JOURNAL OF ENVIRONMENTAL MANAGEMENT, vol. 253.View/Download from: Publisher's site
Suwaileh, W, Pathak, N, Shon, H & Hilal, N 2020, 'Forward osmosis membranes and processes: A comprehensive review of research trends and future outlook', Desalination, vol. 485, pp. 114455-114455.View/Download from: Publisher's site
Naidu, G, Tijing, L, Johir, MAH, Shon, H & Vigneswaran, S 2020, 'Hybrid membrane distillation: Resource, nutrient and energy recovery', JOURNAL OF MEMBRANE SCIENCE, vol. 599.View/Download from: Publisher's site
Hossain, SM, Park, MJ, Park, HJ, Tijing, L, Kim, J-H & Shon, HK 2019, 'Preparation and characterization of TiO2 generated from synthetic wastewater using TiCl4 based coagulation/flocculation aided with Ca(OH)2.', Journal of environmental management, vol. 250.View/Download from: Publisher's site
This study focused on the preparation of undoped and Ca-doped titania from flocculation generated sludge. Initially, TiCl4 was utilised to perform coagulation and flocculation in synthetic wastewater and an optimised dose of coagulant was determined by evaluating the turbidity, dissolved organic carbon (DOC) and zeta potential of the treated water. Later, using Ca(OH)2 as a coagulant aid, the effects on effluent pH, turbidity and DOC removal were investigated. Both Ca-doped and undoped anatase TiO2 were prepared from the flocculated sludge for morphological and photocatalytic evaluation. During the standalone use of TiCl4, maximum turbidity and DOC removal were found at 11.63 and 14.54 mg Ti/L, respectively. At the corresponding coagulant dose, rapid deprotonation of water caused the pH of the effluent to reach below 3.77 mg Ti/L. Whereas, when using Ca(OH)2 as a coagulant aid, a neutral pH (7.26) was attained at a simultaneous dosing of 32.40 mg Ca/L and 14.54 mg Ti/L. When aided with Ca(OH)2, the turbidity removal was further increased by 54.28% and the DOC removal was somewhat similar to the standalone use of TiCl4. TiO2 was prepared by incinerating the collected sludge at 600 °C for 2 h. Both XRD and SEM analysis were conducted to observe the morphology of the prepared titania. The XRD pattern of the TiO2 showed only an anatase phase along with the presence of a high atomic proportion of Ca (4.14%). Consequently, a high amount of Ca atoms inhibited the level of TiO2 phase and no obvious presence of CaO was observed. The prepared Ca-doped TiO2 at the optimised dose of Ca(OH)2 was found to be inferior to the undoped TiO2 during the photodegradation of acetaldehyde. However, a reduced dose of Ca(OH)2 (<15 mg Ca/L) exhibited a substantial increase in photoactivity under UV irradiance.
Ren, J, Woo, YC, Yao, M, Lim, S, Tijing, LD & Shon, HK 2019, 'Nanoscale zero-valent iron (nZVI) immobilization onto graphene oxide (GO)-incorporated electrospun polyvinylidene fluoride (PVDF) nanofiber membrane for groundwater remediation via gravity-driven membrane filtration.', The Science of the total environment, vol. 688, pp. 787-796.View/Download from: Publisher's site
Nanoscale zero-valent iron (nZVI), with its high reactivity towards a broad range of contaminants, has been a promising material for groundwater remediation. Membrane-supported nZVI can both avoid nZVI agglomeration for better reactivity and recycle nZVI to lower the risk of secondary pollution. In this study, we successfully fabricated a PVDF-GO membrane via electrospinning technology and employed the functionalized nanofiber membrane to immobilize nZVI particles. The addition of GO into PVDF nanofibers can both increase the hydrophilicity to improve membrane flux and offer -COOH as a binder to immobilize nZVI particles. PVDF-GO-nZVI membranes with different GO loadings (0%, 0.5%, 1%, 3% of PVDF) were tested with two typical nZVI-targeted contaminants (Cd(II) and trichloroethylene (TCE)) via gravity-driven membrane filtration. The results show that membrane with 1% GO had the best nZVI distribution against the aggregation and a better performance in both Cd removal (100%) and TCE removal (82%). The nZVI membrane had a high flux in gravity-driven filtration at 255 LMH for Cd(II) and 265 LMH for TCE respectively. Generally, the developed PVDF-GO-nZVI electrospun nanofiber membrane had an excellent performance in the gravity-driven membrane filtration system for groundwater remediation.
Ren, J, Yao, M, Woo, YC, Tijing, LD, Kim, J-H & Shon, HK 2019, 'Recyclable nanoscale zerovalent iron (nZVI)-immobilized electrospun nanofiber composites with improved mechanical strength for groundwater remediation', COMPOSITES PART B-ENGINEERING, vol. 171, pp. 339-346.View/Download from: Publisher's site
Yao, M, Ren, J, Akther, N, Woo, YC, Tijing, LD, Kim, S-H & Shon, HK 2019, 'Improving membrane distillation performance: Morphology optimization of hollow fiber membranes with selected non-solvent in dope solution', CHEMOSPHERE, vol. 230, pp. 117-126.View/Download from: Publisher's site
Yao, M, Woo, YC, Ren, J, Tijing, LD, Choi, J-S, Kim, S-H & Shon, HK 2019, 'Volatile fatty acids and biogas recovery using thermophilic anaerobic membrane distillation bioreactor for wastewater reclamation.', Journal of environmental management, vol. 231, pp. 833-842.View/Download from: Publisher's site
The effects of bioreactor temperatures and salinities of an anaerobic membrane distillation bioreactor (anMDBR) on the permeation performance and their potential recovery of bioresources were fully examined in this study. To the best of our knowledge, this is the first study of a lab-scale anMDBR process utilizing sub-merged hollow fiber membranes. The hybrid system utilizing both membrane distillation (MD) and anaerobic bioreactors achieved 99.99% inorganic salt rejection regardless the operation temperatures and high initial flux from (2-4 L m-2 h-1) at 45-65 °C. However, after 7-day operation, the flux dropped by 16-50% proportional to the bioreactor temperatures. It was found that the effects of bioreactor temperatures had strong impacts on both the permeation performance and fouling behavior while salinity had insignificant effect. A compact non-porous fouling layer was observed on the membrane surface from the bioreactor operated at 65 °C while only a few depositions was found on the membrane from 45 °C bioreactor. In the present study, the optimal anMDBR temperature was found to be 45 °C, showing a balanced biogas production and membrane permeation performance including less fouling formation. At this bioreactor temperature (45 °C), the biogas yield was 0.14 L/g CODremoval, while maintaining a methane recovery of 42% in the biogas, similar recovery to those at bioreactor temperatures of 55 and 65 °C. The potential recovery of volatile fatty acids made anMDBR a more economically efficient system, in addition to its lower operation cost and smaller footprint compared with most other technologies for on-site wastewater treatment.
Gonzales, RR, Park, MJ, Bae, T-H, Yang, Y, Abdel-Wahab, A, Phuntsho, S & Shon, HK 2019, 'Melamine-based covalent organic framework-incorporated thin film nanocomposite membrane for enhanced osmotic power generation', DESALINATION, vol. 459, pp. 10-19.View/Download from: Publisher's site
Park, MJ, Lim, S, Gonzales, RR, Phuntsho, S, Han, DS, Abdel-Wahab, A, Adham, S & Shon, HK 2019, 'Thin-film composite hollow fiber membranes incorporated with graphene oxide in polyethersulfone support layers for enhanced osmotic power density', Desalination, vol. 464, pp. 63-75.View/Download from: Publisher's site
© 2019 Elsevier B.V. This study focused on the development of pressure retarded osmosis (PRO) thin film composite (TFC) membranes for enhanced osmotic power using hollow fiber polyethersulfone (PES) support structure modified by incorporating hydrophilic graphene oxide (GO) nanosheets. The GO loadings in the hollow fiber substrates were varied to improve water flux performances without compromising the mechanical strength. GO embedded (≤0.2 wt%) PES hollow fiber supports revealed noticeable improvements in pure water permeability, improved structural morphologies, as well as the hydrophilicity within the support layer, without deteriorating the mechanical properties. The GO (0.2 wt%)-incorporated TFC-PRO membrane appeared to have an initial PRO flux (without any applied pressure) of 43.74 L m−2 h−1, lower specific reverse salt flux of 0.04 g L−1 and structural parameter (S) of 522 μm, significantly better than the control membrane. The maximum power density of 14.6 W m−2 was achieved at an operating pressure of 16.5 bar under the condition of DI water and 1 M NaCl as feed and draw solutions, respectively. The results obtained in this study indicate that modification of PRO hollow fiber support layer by incorporating nanoparticles such as GO nanosheet can be a useful tool to improve the PRO performance.
Akther, N, Lim, S, Tran, VH, Phuntsho, S, Yang, Y, Bae, TH, Ghaffour, N & Shon, HK 2019, 'The effect of Schiff base network on the separation performance of thin film nanocomposite forward osmosis membranes', Separation and Purification Technology, vol. 217, pp. 284-293.View/Download from: Publisher's site
© 2019 Elsevier B.V. In this study, Schiff base network-1 (SNW-1) nanoparticles, which are covalent organic frameworks (COFs), were used as fillers in the polyamide (PA) active layer to elevate the performance of thin-film nanocomposite (TFN) forward osmosis (FO) membranes. The TFN membranes were prepared by interfacial polymerization (IP) of m-phenylenediamine (MPD) and trimesoyl chloride (TMC), and the SNW-1 nanoparticles were dispersed in the MPD aqueous solution at various concentrations. The secondary amine groups of SNW-1 nanoparticles reacted with the acyl chloride groups of TMC during the IP reaction to form strong covalent/amide bonds, which facilitated better interface integration of SNW-1 nanoparticles in the PA layer. Additionally, the incorporation of amine-rich SNW-1 nanoparticles into the TFN membranes improved their surface hydrophilicity, and the porous structure of SNW-1 nanoparticles offered additional channels for transport of water molecules. The TFN0.005 membrane with a SNW-1 nanoparticle loading of 0.005 wt% demonstrated a higher water flux than that of pristine TFC membrane in both AL-FS (12.0 vs. 9.3 L m−2 h−1) and AL-DS (25.2 vs. 19.4 L m−2 h−1) orientations when they were tested with deionized water and 0.5 M NaCl as feed and draw solution, respectively.
Akther, N, Phuntsho, S, Chen, Y, Ghaffour, N & Shon, HK 2019, 'Recent advances in nanomaterial-modified polyamide thin-film composite membranes for forward osmosis processes', JOURNAL OF MEMBRANE SCIENCE, vol. 584, pp. 20-45.View/Download from: Publisher's site
Ali, SM, Qamar, A, Kerdi, S, Phuntsho, S, Vrouwenvelder, JS, Ghaffour, N & Shon, HK 2019, 'Energy efficient 3D printed column type feed spacer for membrane filtration.', Water research, vol. 164.View/Download from: Publisher's site
Modification of the feed spacer design significantly influences the energy consumption of membrane filtration processes. This study developed a novel column type feed spacer with the aim to reduce the specific energy consumption (SEC) of the membrane based water filtration system. The proposed spacer increases the clearance between the filament and the membrane (reducing the spacer filament diameter) while keeping the same flow channel thickness as compared to a standard non-woven symmetric spacer. Since the higher clearance reduces the flow unsteadiness, column type nodes were added in the spacer structure as additional vortex shading bodies. Fluid flow behaviour in the channel for this spacer was numerically simulated by 3D CFD studies and then compared with the standard spacer. The numerical results showed that the proposed spacer substantially reduced the pressure drop, shear stress at the constriction region and shortened the dead zone. Finally, these findings were confirmed experimentally by investigating the filtration performances using the 3D printed prototypes of these spacers in a lab-scale filtration module. It is observed that the column spacer reduced the pressure drop by three times and doubled the specific water flux. 2D OCT (Optical Coherence Tomography) scans of the membrane surface acquired after the filtration revealed much lower biomass accumulation using the proposed spacer. Consequently, the SEC for the column spacer was found about two folds lower than the standard spacer.
Choi, J, Dorji, P, Shon, HK & Hong, S 2019, 'Applications of capacitive deionization: Desalination, softening, selective removal, and energy efficiency', Desalination, vol. 449, pp. 118-130.View/Download from: Publisher's site
© 2018 Elsevier B.V. Capacitive deionization (CDI) has attracted a great attention as a promising desalination technology, and studies on CDI have increased significantly in the last ten years. However, there have been no guidelines for developing strategies involving CDI technology for specific applications. Therefore, our work presents a critical review of the recent advances in CDI to meet the technical requirements of various applicable areas, with an emphasis on hybrid systems. This paper first summarizes the major developments made on novel electrode materials for CDI for brackish water desalination. Then, CDI and reverse osmosis (RO) integrated systems are critically reviewed for both ultrapure water production and wastewater treatment. Additionally, the applicability of CDI on various industrial processes is discussed, covering two distinct topics: (1) water softening and (2) selective removal of valuable heavy metals and nutrients (nitrate/phosphate). Lastly, recent improvements on the energy efficiency of CDI processes are delineated, specifically focusing on energy recovery and hybridization with energy producing technology, such as reverse electrodialysis (RED) and microbial fuel cells (MFC). This review paper is expected to share the practical experience of CDI applications as well as to provide guidelines for electrode material development for each specific application.
Choi, J, Dorji, P, Shon, HK & Hong, S 2019, 'Applications of capacitive deionization: Desalination, softening, selective removal, and energy efficiency (vol 449, pg 118, 2019)', DESALINATION, vol. 468.View/Download from: Publisher's site
Damtie, MM, Woo, YC, Kim, B, Hailemariam, RH, Park, K-D, Shon, HK, Park, C & Choi, J-S 2019, 'Removal of fluoride in membrane-based water and wastewater treatment technologies: Performance review.', Journal of environmental management, vol. 251.View/Download from: Publisher's site
The presence of excess fluoride in aqueous media above local environmental standards (e.g., the U.S. Environmental Protection Agency (EPA) standard of 4 mg/L) affects the health of aquatic life. Excess fluoride in drinking water above the maximum contaminant level (e.g., the World Health Organization (WHO) standard of 1.5 mg/L) also affects the skeletal and nervous systems of humans. Fluoride removal from aqueous solutions is difficult using conventional electrochemical, precipitation, and adsorption methods owing to its ionic size and reactivity. Thus, new technologies have been introduced to reduce the fluoride concentration in industrial wastewater effluents and various drinking water sources. Membrane technology is one of the newer technologies found to be very effective in significantly reducing fluoride to desired standards levels; however, it has received less attention than other technologies because it is perceived as a costly process. This study critically reviewed the performance of various membrane process and compared it with effluent and zero liquid discharge (ZLD) standards. The performance review has been conducted with the consideration of the theoretical background, rejection mechanisms, technical viability, and parameters affecting flux and rejection performance. This review includes membrane systems investigated for the defluoridation process but operated under pressure (i.e., reverse osmosis [RO] and nanofiltration [NF]), temperature gradients (i.e., membrane distillation [MD]), electrical potential gradients (i.e., electrodialysis [ED] and Donnan dialysis [DD]), and concentration differences (i.e., forward osmosis [FO]). Moreover, the study also addressed the advantages, limitations, & applicable conditions of each membrane based defluoridation process.
Damtie, MM, Woo, YC, Kim, B, Park, K-D, Hailemariam, RH, Shon, HK & Choi, J-S 2019, 'Analysis of mass transfer behavior in membrane distillation: Mathematical modeling under various conditions', CHEMOSPHERE, vol. 236.View/Download from: Publisher's site
Dorji, P, Kim, DI, Jiang, J, Choi, J, Phuntsho, S, Hong, S & Shon, HK 2019, 'Bromide and iodide selectivity in membrane capacitive deionisation, and its potential application to reduce the formation of disinfection by-products in water treatment', CHEMOSPHERE, vol. 234, pp. 536-544.View/Download from: Publisher's site
Dorji, U, Tenzin, UM, Dorji, P, Wangchuk, U, Tshering, G, Dorji, C, Shon, H, Nyarko, KB & Phuntsho, S 2019, 'Wastewater management in urban Bhutan: Assessing the current practices and challenges', Process Safety and Environmental Protection, vol. 132, pp. 82-93.View/Download from: Publisher's site
© 2019 Institution of Chemical Engineers This study reviews the current wastewater management practices and their challenges in urban Bhutan. The study data was collected from the local authorities of 35 classified towns, and the field survey was conducted for the two representative towns of Thimphu City and Khuruthang town. The study observed that only eight of the 35 classified towns (22.8%) have public sewerage systems, with an average coverage of 19.7% of Bhutan's total urban population, or 7.4% of Bhutan's entire population. The imported modular wastewater treatment technology was significantly more expensive than alternative options; however, approximately six towns have already adopted this technology, due to a lack of space for a much cheaper waste stabilisation ponds. Currently, over 80% of Bhutan's urban population depends on the on-site sanitation system for their domestic wastewater disposal; however, over 40% of these properties lacked a soak-pit system for the safe disposal of septic tank effluent. Therefore, this study indicates that urban settlements in Bhutan are potentially subjected to overflow of significant amount of hazardous septic tank effluents directly into the environment posing significant risk to public and the environment. A critical urban plot space analysis indicates that the current system of on-site sanitation is inadequate and unsuitable for the current urban settings. Since it is impractical for the government to provide public sewerage system to all the towns, a low-cost public sewerage system, or an alternative and improved on-site treatment system, needs to be explored and promoted to achieve long-term environmental objectives.
Im, SJ, Shon, HK, Kim, IS & Jang, A 2019, 'The effects of naturally occurring operation factors on the removal mechanism of major algae metabolized materials in forward osmosis process', Journal of Cleaner Production, vol. 239.View/Download from: Publisher's site
© 2019 Elsevier Ltd This research investigated the removal mechanism of algae metabolized materials (geosmin, 2-methylisoborneol (2-MIB), and microcystin-leucine arginine (MC-LR)) according to the naturally occurring operation factors such as temperature (10, 20 and 30 °C), transmembrane temperature (20 °C: 10 vs. 30, 30 vs. 10 °C) difference and valance of reverse salt flux (RSF) in forward osmosis membrane. Algae metabolized materials had high removal efficiency (94–99%) at all experimental conditions. According to the temperature difference, the absorption percentage of geosmin and 2-MIB on the FO membrane was 76, 75% and 75, 55%, respectively. However, adsorption percentage of toxin (MC-LR) materials were observed to be 11 and 85%, respectively. Temperature-dependent parameters such as water and solute viscosity & diffusivity, membrane intrinsic properties, have effects on the removal mechanism and rate. Consequently, the results from this research provide meaningful information on not only the removal of algae metabolized materials like micropollutants but also the water treatment process with consideration of the temperature conditions (temperature difference).
Jiang, J, Kim, DI, Dorji, P, Phuntsho, S, Hong, S & Shon, HK 2019, 'Phosphorus removal mechanisms from domestic wastewater by membrane capacitive deionization and system optimization for enhanced phosphate removal', PROCESS SAFETY AND ENVIRONMENTAL PROTECTION, vol. 126, pp. 44-52.View/Download from: Publisher's site
Katz, A, Shon, HK, Chekli, L & Kim, J-H 2019, 'TiO₂-Coated Optical Fibres for Groundwater Remediation.', Journal of nanoscience and nanotechnology, vol. 19, no. 2, pp. 1086-1089.View/Download from: Publisher's site
In this study, polyethylene glycol (PEG) was tested as an alternative polymer to improve the coating of TiO₂ particles onto optical fibres. The addition of PEG helped dispersing effectively the particles in solution to control their deposition and therefore achieving better properties of the coating film. Results showed that PEG increased the effectiveness of the coating and the prepared fibres showed better performance for the removal of methylene blue (MB). This was attributed to the morphological changes induced by PEG. EDX mapping of the fibre surface showed that the addition of PEG lead to a better coverage of the fibre surface; increasing the active surface area for subsequent photocatalytic degradation. This study also showed that the light intensity, pH and initial concentration of MB have a significant influence. Finally, it was demonstrated that the coatings using PEG were better ordered and structured; showing a distinct layer-by-layer deposition.
Kim, B-J, Piao, G, Kim, S, Yang, SY, Park, Y, Han, DS, Shon, HK, Hoffmann, MR & Park, H 2019, 'High-Efficiency Solar Desalination Accompanying Electrocatalytic Conversions of Desalted Chloride and Captured Carbon Dioxide', ACS SUSTAINABLE CHEMISTRY & ENGINEERING, vol. 7, no. 18, pp. 15320-15328.View/Download from: Publisher's site
Kim, DI, Dorji, P, Gwak, G, Phuntsho, S, Hong, S & Shon, H 2019, 'Effect of Brine Water on Discharge of Cations in Membrane Capacitive Deionization and Its Implications on Nitrogen Recovery from Wastewater', ACS Sustainable Chemistry and Engineering, vol. 7, no. 13, pp. 11474-11484.View/Download from: Publisher's site
© 2019 American Chemical Society. We examined the desorption behavior of cations in membrane capacitive deionization (MCDI) from the cathode into high-concentration brine through a cation-exchange membrane (CEM) brine, during mineral recovery. Several major issues were explored to demonstrate the suitability of the mineral recovery process: discharge behavior using different solution chemistries, desorption efficiencies of various regeneration methods for the enrichment of ions, and desorption selectivity among selected cations. The desorption efficiency was hampered when the adsorbed cations migrated toward the brine solution against a higher ionic-strength gradient and was further lowered by the enhanced membrane resistance under the low concentration of the adsorbed ions on the cathode. Furthermore, the electrochemically adsorbed ions were limitedly discharged by the cost-effective regeneration method (short-circuiting). The cations were preferentially released in the order of K+ > Na+ > Mg2+, as mainly determined by their physiochemical properties such as diffusion rate and charge valence, whereas the influence of permselectivity through the CEM was insignificant. Furthermore, through the ammonium recovery tests, a high concentration of ammonium brine was obtained from wastewater through a successive five-cycle-operation due to its selective desorption over the sodium ions present. However, the incomplete discharge of ions from the electrode was a challenging issue to overcome for the use of MCDI for ammonium recovery.
Kim, DI, Dorji, P, Gwak, G, Phuntsho, S, Hong, S & Shon, H 2019, 'Reuse of municipal wastewater via membrane capacitive deionization using ion-selective polymer-coated carbon electrodes in pilot-scale', Chemical Engineering Journal, vol. 372, pp. 241-250.View/Download from: Publisher's site
© 2019 Elsevier B.V. This study investigated membrane capacitive deionization (MCDI) at a pilot-scale using ion-selective polymer-coated carbon electrodes for wastewater reuse. Several issues have been addressed to verify the suitability of MCDI for wastewater reclamation: electrosorption performance, removal efficiency and selectivity of ions present in wastewater, optimization of operating conditions, and performance degradation in long-term caused by the accumulation of organic contaminants. The coated electrodes had better adsorption capacities and charge efficiencies than the conventional MCDI system, which was attributed to their low electrical resistance induced by the thin coated layer. The pilot-scale MCDI test cell involved 50 pairs of anion- and cation-selective electrodes and achieved good removal efficiency of ions from the wastewater effluent, particularly for problematic charged impurities, such as nitrate (NO3−) (up to 91.08% of NO3− was removed). Increasing the flow rate and reducing the applied potential were shown to be efficient for achieving better water quality by enhancing the NO3− selectivity. Last, the 15 d operation showed good reproducibility in electrosorption and regeneration for the coated electrodes, despite the fact that high concentrations of organics were contained in the wastewater feed solution (12.4 mg/L of dissolved organic carbon).
Kim, JE, Kuntz, J, Jang, A, Kim, IS, Choi, JY, Phuntsho, S & Shon, HK 2019, 'Techno-economic assessment of fertiliser drawn forward osmosis process for greenwall plants from urban wastewater', Process Safety and Environmental Protection, vol. 127, pp. 180-188.View/Download from: Publisher's site
© 2019 Institution of Chemical Engineers Pressure-assisted osmosis (PAO) has been suggested to integrate with fertiliser driven forward osmosis (FDFO) to improve the overall efficiency of simultaneous wastewater reuse and fertiliser osmotic dilution. This study aims to demonstrate the techno-economic feasibility of pressure-assisted fertiliser driven forward osmosis (PAFDO) hybrid system compared to the existing ultraviolet and reverse osmosis (UV–RO) process. The results showed that coupling FDFO with PAO (i.e. PAFDO) could help fulfill the water quality required for greenwall fertigation. An economic analysis on capital and operational costs for the PAFDO showed that the PAO mode application at a lower FDFO dilution stage could significantly reduce the costs. However, when considering the different applied pressures in PAO (i.e. 2, 4, and 6 bar), the increase in the total water cost was not significant. This indicates that the dilution stage for applying PAO is more sensitive to the total water cost of the PAFDO than the applied pressure. A coupling of higher average water flux (>10 L/m2h) and lower draw solution (DS) dilution factor (DF < 60) is recommended. Therefore, this could make the PAFDO system economically viable compared to the benchmark for the UV-RO disinfection system.
Kim, Y, Li, S, Phuntsho, S, Xie, M, Shon, HK & Ghaffour, N 2019, 'Understanding the organic micropollutants transport mechanisms in the fertilizer-drawn forward osmosis process.', Journal of environmental management, vol. 248.View/Download from: Publisher's site
We systematically investigated the transport mechanisms of organic micropollutants (OMPs) in a fertilizer-drawn forward osmosis (FDFO) membrane process. Four representative OMPs, i.e., atenolol, atrazine, primidone, and caffeine, were chosen for their different molecular weights and structural characteristics. All the FDFO experiments were conducted with the membrane active layer on the feed solution (FS) side using three different fertilizer draw solutions (DS): potassium chloride (KCl), monoammonium phosphate (MAP), and diammonium phosphate (DAP) due to their different properties (i.e., osmotic pressure, diffusivity, viscosity and solution pH). Using KCl as the DS resulted in both the highest water flux and the highest reverse solute flux (RSF), while MAP and DAP resulted in similar water fluxes with varying RSF. The pH of the FS increased with DAP as the DS due to the reverse diffusion of NH4+ ions from the DS toward the FS, while for MAP and DAP DS, the pH of the FS was not impacted. The OMPs transport behavior (OMPs flux) was evaluated and compared with a simulated OMPs flux obtained via the pore-hindrance transport model to identify the effects of the OMPs structural properties. When MAP was used as DS, the OMPs flux was dominantly influenced by the physicochemical properties (i.e., hydrophobicity and surface charge). Those OMPs with positive charge and more hydrophobic, exhibited higher forward OMP fluxes. With DAP as the DS, the more hydrated FO membrane (caused by increased pH) as well as the enhanced RSF hindered OMPs transport through the FO membrane. With KCl as DS, the structural properties of the OMPs were dominant factors in the OMPs flux, however the higher RSF of the KCl draw solute may likely hamper the OMPs transport through the membrane especially those with higher MW (e.g., atenolol). The pore-hindrance model can be instrumental in understanding the effects of the hydrodynamic properties and the surface properties on the OMPs transport behavi...
Lee, S, Choi, J, Park, YG, Shon, H, Ahn, CH & Kim, SH 2019, 'Hybrid desalination processes for beneficial use of reverse osmosis brine: Current status and future prospects', Desalination, pp. 104-111.View/Download from: Publisher's site
© 2018 Elsevier B.V. As water shortage has increasingly become a serious global problem, desalination using seawater reverse osmosis (SWRO) is considered as a sustainable source of potable water sources. However, a major issue on the SWRO desalination plant is the generation of brine that has potential adverse impact due to its high salt concentration. Accordingly, it is necessary to develop technologies that allow environmentally friendly and economically viable management of SWRO brines. This paper gives an overview of recent research works and technologies to treat SWRO brines for its beneficial use. The treatment processes have been classified into two different groups according to their final purpose: 1) technologies for producing fresh water and 2) technologies for recovering energy. Topics in this paper includes membrane distillation (MD), forward osmosis (FO), pressure-retarded osmosis (PRO), reverse electrodialysis (RED) as emerging tools for beneficial use of SWRO brine. In addition, a new approach to simultaneously recover water and energy from SWRO brine is introduced as a case study to provide insight into improving the sustainability of seawater desalination.
Lim, S, Tran, VH, Akther, N, Phuntsho, S & Shon, HK 2019, 'Defect-free outer-selective hollow fiber thin-film composite membranes for forward osmosis applications', Journal of Membrane Science, vol. 586, pp. 281-291.View/Download from: Publisher's site
© 2019 Elsevier B.V. This study presents the successful fabrication of a novel defect-free outer-selective hollow fiber (OSHF) thin-film composite (TFC) membrane for forward osmosis (FO) applications. Thin and porous FO membrane substrates made of polyether sulfone (PES) with a dense and smooth outer surface were initially fabricated at different air-gap distances. A modified vacuum-assisted interfacial polymerization (VAIP) technique was then successfully utilised for coating polyamide (PA) layer on the hollow fiber (HF) membrane substrate to prepare OSHF TFC membranes. Experimental results showed that the molecular weight cut-off (MWCO) of the surface of the membrane substrate should be less than 88 kDa with smooth surface roughness to obtain a defect-free PA layer via VAIP. The FO test results showed that the newly developed OSHF TFC membranes achieved water flux of 30.2 L m−2 h−1 and a specific reverse solute flux of 0.13 g L−1 using 1 M NaCl and DI water as draw and feed solution, respectively. This is a significant improvement on commercial FO membranes. Moreover, this OSHF TFC FO membrane demonstrated higher fouling resistance and better cleaning efficiency against alginate-silica fouling. This membrane also has a strong potential for scale-up for use in larger applications. It also has strong promise for various FO applications such as osmotic membrane bioreactor (OMBR) and fertilizer-drawn OMBR processes.
Oh, S-H, Jeong, S, Kim, IS, Shon, HK & Jang, A 2019, 'Removal behaviors and fouling mechanisms of charged antibiotics and nanoparticles on forward osmosis membrane.', Journal of environmental management, vol. 247, pp. 385-393.View/Download from: Publisher's site
Fouling and rejection mechanisms of both charged antibiotics (ABs) and nanoparticles (NPs) were determined using a negatively-charged polyamide thin film composite forward osmosis (FO) flat sheet membrane. Two types of ABs and NPs were selected as positively and negatively charged foulants at pH 8. The ABs did not cause significant membrane fouling, but the extent of fouling and rejection changed based on the electrostatic attraction or repulsion forces. The addition of opposite charged AB and NP resulted in a decline of the membrane flux by 11.0% but a 6.5% AB average rejection efficiency improvement. On the other hand, mixing of like-charged ABs and NPs generated repulsive forces that improved average rejection efficiency about 5.5% but made no changes in the membrane flux. In addition, NPs and ABs were mixed and tested at various concentrations and pH levels to rectify the behavior of ABs. The aggregate size and removal efficiency were observed to vary with the change in the electron double layer of the mixture. It can help to make the strategy to control the ABs in the FO process and consequently it enables the FO process to produce environmentally safe effluent.
Shon, HK, Jegatheesan, V & Chiemchaisri, C 2019, 'Challenges in environmental science and engineering 2018', Process Safety and Environmental Protection, vol. 131, pp. 329-330.View/Download from: Publisher's site
Song, J-H, Shon, HK, Wang, P, Jang, A & Kim, IS 2019, 'Tuning the nanostructure of nitrogen-doped graphene laminates for forward osmosis desalination.', Nanoscale, vol. 11, no. 45, pp. 22025-22032.View/Download from: Publisher's site
Studies have concentrated on the physicochemical properties of graphene-based membranes that can replace polymeric membranes for use in forward osmosis (FO) systems. However, recent research studies have focused on mixtures of two or more different materials (e.g., graphene oxide and polymers) due to the need to reinforce underwater stability. Alternatives include reduced forms such as reduced graphene oxide to improve the stability and size-based selectivity, which have resulted in a narrow nanochannel that restricts water permeability. Herein, we propose the use of a novel nitrogen-doped graphene (NG) membrane to solve a trade-off between permeability and selectivity, investigating the nanostructure via N-doping reaction time. In an FO process, NG membranes achieved an outstanding specific salt flux of 0.18 g L-1, compared to commercial membranes (0.55 g L-1). The pyridinic-N bonding structure improved the permeability and selectivity under a similar nanochannel size because of its negatively polarized hole defects with the moderate energy barrier enabling water passage while blocking ions. Our results confirm the possibility of fabricating novel graphene-based FO membranes by tailoring the nitrogen-bonding structure, which will significantly help develop a process for improving the scalability of membrane materials.
Volpin, F, Chekli, L, Phuntsho, S, Ghaffour, N, Vrouwenvelder, JS & Shon, HK 2019, 'Optimisation of a forward osmosis and membrane distillation hybrid system for the treatment of source-separated urine', SEPARATION AND PURIFICATION TECHNOLOGY, vol. 212, pp. 368-375.View/Download from: Publisher's site
Volpin, F, Heo, H, Johir, M, Cho, J, Phuntsho, S & Shon, HK 2019, 'Techno-economic feasibility of recovering phosphorus, nitrogen and water from dilute human urine via forward osmosis.', Water research, vol. 150, pp. 47-55.View/Download from: Publisher's site
Due to high phosphorus (P) and nitrogen (N) content, human urine has often proven to suitable raw material for fertiliser production. However, most of the urine diverting toilets or male urinals dilute the urine 2 to 10 times. This decreases the efficiency in the precipitation of P and stripping of N. In this work, a commercial fertiliser blend was used as forward osmosis (FO) draw solution (DS) to concentrate real diluted urine. During the concentration, the urea in the urine is recovered as it diffuses to the fertiliser. Additionally, the combination of concentrate PO43-, reverse Mg2+ flux from the DS and the Mg2+ presents in the flushing water, was able to recover the PO43- as struvite. With 50% concentrated urine, 93% P recovery was achieved without the addition of an external Mg2+. Concurrently, 50% of the N was recovered in the diluted fertiliser DS. An economic analysis was performed to understand the feasibility of this process. It was found that the revenue from the produced fertilisers could potentially offset the operational and capital costs of the system. Additionally, if the reduction in the downstream nutrients load is accounted for, the total revenue of the process would be over 5.3 times of the associated costs.
Volpin, F, Yu, H, Cho, J, Lee, C, Phuntsho, S, Ghaffour, N, Vrouwenvelder, JS & Shon, HK 2019, 'Human urine as a forward osmosis draw solution for the application of microalgae dewatering.', Journal of Hazardous Materials, vol. 378, pp. 120724-120724.View/Download from: Publisher's site
Human urine is a unique solution that has the right composition to constitute both a severe environmental threat and a rich source of nitrogen and phosphorous. In fact, between 4-9% of urine mass consists of ions, such as K+, Cl-, Na+ or NH4+. Because of its high ionic strength, urine osmotic pressure can reach values of up to 2000 kPa. With this in mind, this work aimed to study the effectiveness of real urine as a novel draw solution for forward osmosis. Water flux, reverse nitrogen flux and membrane fouling were investigated using fresh or hydrolysed urine. Water flux as high as 16.7 ± 1.1 L m-2 h-1 was recorded using real hydrolysed urine. Additionally, no support layer membrane fouling was noticed in over 20 h of experimentation. Urine was also employed to dewater a Chlorella vulgaris culture. A fourfold increase in algal concentration was achieved while having an average flux of 14.1 L m-2 h-1. During the algae dewatering, a flux decrease of about 19% was noticed; this was mainly due to a thin layer of algal deposition on the active side of the membrane. Overall, human urine was found to be an effective draw solution for forward osmosis.
Yang, S, Gao, B, Jang, A, Shon, HK & Yue, Q 2019, 'Municipal wastewater treatment by forward osmosis using seawater concentrate as draw solution.', Chemosphere, vol. 237.View/Download from: Publisher's site
Forward osmosis (FO) has been used in the wastewater treatment due to its advantages including low energy consumption and low membrane fouling. In this study, real municipal wastewater was concentrated by FO process using seawater concentrate as draw solution (DS). The influences of operating conditions such as temperature, flow velocity and sewage pre-filtration on water flux were investigated. Chemical oxygen demand, total nitrogen, ammonia nitrogen and total phosphorus could not be enriched by 4 times while sewage was reduced to 1/4 volume. Excitation and emission matrix fluorescence spectrum showed that a fraction of dissolved organic compounds in sewage transported across membrane into DS. Membrane fouling was evaluated by scanning electronic microscope analysis that a dense cake layer was formed on the membrane surface after sewage filtration. However, water flux of the fouled membrane was highly recovered after 1 h of physical cleaning.
Yang, S, Gao, B, Zhao, P, Wang, C, Shen, X, Yue, Q & Shon, HK 2019, 'The application of forward osmosis for simulated surface water treatment by using trisodium citrate as draw solute.', Environmental science and pollution research international, vol. 26, no. 9, pp. 8585-8593.View/Download from: Publisher's site
In this study, trisodium citrate was used as draw solute in forward osmosis (FO) due to its biodegradability and easy reuse after FO dilution. The effect of operating conditions on FO performance was investigated. The study focused on the long-term flux performance and membrane fouling when surface water was used as feed solution. A water flux of 9.8 LMH was observed using 0.5 M trisodium citrate as draw solution in PRO mode. In the long-term FO process, trisodium citrate showed a slight decrease in total flux loss (13.06%) after 20 h of operation. The membrane fouling was significantly reduced after a two-step physical cleaning. A considerable flux recovery (> 95%) of the fouled membrane was finally obtained. Therefore, this study proves the superiority of trisodium citrate as draw solution and paves a new way in applying FO directly for surface water reclamation.
Tran, VH, Lim, S, Han, DS, Pathak, N, Akther, N, Phuntsho, S, Park, H & Shon, HK 2019, 'Efficient fouling control using outer-selective hollow fiber thin-film composite membranes for osmotic membrane bioreactor applications.', Bioresource technology, vol. 282, pp. 9-17.View/Download from: Publisher's site
This paper investigates the efficiency of fouling mitigation methods using a novel outer selective hollow fiber thin-film composite forward osmosis (OSHF TFC FO) membrane for osmosis membrane bioreactor (OMBR) system treating municipal wastewater. Two home-made membrane modules having similar transport properties were used. Two operation regimes with three different fouling mitigation strategies were utilized to test the easiness of membrane for fouling cleaning. These two membrane modules demonstrated high performance with high initial water flux of 14.4 LMH and 14.1 LMH and slow increase rate of mixed liquor's salinity in the bioreactor using 30 g/L NaCl as draw solution. OMBR system showed high removals of total organic carbon and NH4 + -N (>98%). High fouling cleaning efficiency was achieved using OSHF TFC FO membrane with different fouling control methods. These results showed that this membrane is suitable for OMBR applications due to its high performance and its simplicity for fouling mitigation.
Khan, JA, Shon, HK & Nghiem, LD 2019, 'From the Laboratory to Full-Scale Applications of Forward Osmosis: Research Challenges and Opportunities', Current Pollution Reports, vol. 5, no. 4, pp. 337-352.View/Download from: Publisher's site
© 2019, Springer Nature Switzerland AG. Forward osmosis (FO) has recently emerged as a new separation platform for a range of applications that are currently not possible for other membrane processes. This review paper covers key aspects of FO development with a specific emphasis on current technical challenges for practical applications. Main hurdles in the transition of FO from a lab-scale process to large scale applications include low-performance membranes, development of suitable draw solute, inherent transport phenomena (e.g. concentration polarization and reverse solute flux), membrane fouling and subsequent membrane cleaning. Several new FO membranes have been developed with some improved performances but no membrane has yet been found convincing in all of the key performance indicators. Draw solutes have been broadly investigated but mainly at the lab-scale. There have only been very few pilot-scale studies, most of them using inorganic salts as draw solutes. Development of thermo-responsive draw solutes and TFC membranes have been reported to be most effective in reducing reverse solute flux while altering the hydrodynamic conditions and the use of ultrasonication along with exploring other viable options have been suggested to tackle external and internal concentration polarization respectively. Although membrane fouling types and mitigation strategies have been extensively explored, this review also highlights the need for further research in biofouling for long-term FO operation.
Gonzales, RR, Park, MJ, Tijing, L, Han, DS, Phuntsho, S & Shon, HK 2018, 'Modification of Nanofiber Support Layer for Thin Film Composite Forward Osmosis Membranes via Layer-by-Layer Polyelectrolyte Deposition', MEMBRANES, vol. 8, no. 3.View/Download from: Publisher's site
Woo, YC, Kim, Y, Yao, M, Tijing, LD, Cho, J-S, Lee, S, Kim, S-H & Shon, HK 2018, 'Hierarchical Composite Membranes with Robust Omniphobic Surface Using Layer-By-Layer Assembly Technique', ENVIRONMENTAL SCIENCE & TECHNOLOGY, vol. 52, no. 4, pp. 2186-2196.View/Download from: Publisher's site
Yao, M, Woo, YC, Tijing, LD, Choi, JS & Shon, HK 2018, 'Effects of volatile organic compounds on water recovery from produced water via vacuum membrane distillation', Desalination, vol. 440, pp. 146-155.View/Download from: Publisher's site
© 2017 Elsevier B.V. Membrane distillation (MD) has great potentials to treat produced water in energy industries. However, volatile organic compounds (VOCs) existing in the produced water added in the fracking process can hinder the treatment process regarding two aspects: permeate quality and MD flux performance. To address this challenge, this study aims to systematically study the effects of the VOCs on the MD permeation performance and permeate quality, and the mechanism of its penetration. Acetic acid, ethylene glycol, isopropyl alcohol (IPA), and 2-Butoxyethanol (2-BE), which are commonly found in the produced water, were extensively investigated and their impacts were reviewed and compared. Among all the VOCs, 2-BE had the highest mass transfer despite its low vapour pressure and large molecule weight. Some of the VOCs had surfactant properties, which meant they could penetrate the membrane pores easily during MD process. In long-term operation, pore wetting started to appear as the salt rejection was dropping in the MD process, and flux was also decreasing. Based on the results, this study suggested that the strength of surfactant properties and intra-molecular hydrogen bonds between water molecules and VOCs are as significant as vapour pressure for the VOCs in terms of mass transfer efficiency in MD system.
Lim, S, Park, MJ, Phuntsho, S, Mai-Prochnow, A, Murphy, AB, Seo, D & Shon, H 2018, 'Dual-layered nanocomposite membrane incorporating graphene oxide and halloysite nanotube for high osmotic power density and fouling resistance', Journal of Membrane Science, vol. 564, pp. 382-393.View/Download from: Publisher's site
© 2018 Elsevier B.V. This study introduces a thin-film composite (TFC) membrane with a dual-layered nanocomposite substrate synthesized using a dual-blade casting approach for application in osmotic power generation by the pressure-retarded osmosis (PRO) process. The approach incorporates halloysite nanotubes (HNTs) into the bottom polymer substrate layer and graphene oxide (GO) on the top layer substrate, on which a thin polyamide active layer is formed. The fabricated membrane substrate showed highly desirable membrane substrate properties such as a high porosity, opened-bottom surface, suitable top-skin surface morphology for subsequent active layer formation and high mechanical strength, which are essential for high-performance PRO processes. At a GO loading of 0.25 wt% and HNT loading of 4 wt%, the power density (PD) of the nanocomposite membrane was 16.7 W/m 2 and the specific reverse solute flux (SRSF) was 2.4 g/L operated at 21 bar applied pressure using 1 M NaCl as draw solution and deionized water as feed, which is significantly higher than the those for a single-layered or commercial PRO membrane. This membrane performance was observed to be stable in the pressure cycle test and under long-term operation. The membrane substrate with HNTs incorporated exhibited high fouling resistance to sodium alginate and colloidal silica foulants, with the PD decreasing by 17% after 3 h of operation, compared to a membrane substrate without HNTs and commercial PRO membranes, which decreased by 26% and 57%, respectively. A fluorescence microscope study of the membranes subjected to feed water containing Escherichia coli confirmed the good antibacterial properties of the dual-layered TFC membrane. The study provides an attractive alternative approach for developing PRO membranes with high PD and fouling resistance.
Park, MJ, Gonzales, RR, Abdel-Wahab, A, Phuntsho, S & Shon, HK 2018, 'Hydrophilic polyvinyl alcohol coating on hydrophobic electrospun nanofiber membrane for high performance thin film composite forward osmosis membrane', DESALINATION, vol. 426, pp. 50-59.View/Download from: Publisher's site
Seo, DH, Pineda, S, Woo, YC, Xie, M, Murdock, AT, Ang, EYM, Jiao, Y, Park, MJ, Lim, SI, Lawn, M, Borghi, FF, Han, ZJ, Gray, S, Millar, G, Du, A, Shon, HK, Ng, TY & Ostrikov, KK 2018, 'Anti-fouling graphene-based membranes for effective water desalination.', Nature communications, vol. 9, no. 1.View/Download from: Publisher's site
The inability of membranes to handle a wide spectrum of pollutants is an important unsolved problem for water treatment. Here we demonstrate water desalination via a membrane distillation process using a graphene membrane where water permeation is enabled by nanochannels of multilayer, mismatched, partially overlapping graphene grains. Graphene films derived from renewable oil exhibit significantly superior retention of water vapour flux and salt rejection rates, and a superior antifouling capability under a mixture of saline water containing contaminants such as oils and surfactants, compared to commercial distillation membranes. Moreover, real-world applicability of our membrane is demonstrated by processing sea water from Sydney Harbour over 72 h with macroscale membrane size of 4 cm2, processing ~0.5 L per day. Numerical simulations show that the channels between the mismatched grains serve as an effective water permeation route. Our research will pave the way for large-scale graphene-based antifouling membranes for diverse water treatment applications.
Shibuya, M, Park, MJ, Lim, S, Phuntsho, S, Matsuyama, H & Shon, HK 2018, 'Novel CA/PVDF nanofiber supports strategically designed via coaxial electrospinning for high performance thin-film composite forward osmosis membranes for desalination', Desalination, vol. 445, pp. 63-74.View/Download from: Publisher's site
© 2018 Elsevier B.V. This study introduces a novel electrospun nanofiber mat fabricated via coaxial electrospinning as a support for high performance thin-film composite (TFC) forward osmosis (FO) membrane. This method produces a dual layer composite nanofiber support consisted of a polyvinylidene fluoride (PVDF) core layer and a cellulose acetate (CA) sheath layer, which provide mechanical stability and hydrophilicity, respectively. The CA sheath layer aims to cover the hydrophobic core layer and improve its hydrophilicity. The TFC FO membrane with coaxial electrospun CA/PVDF support layer not only showed high improvement in water flux due to improved hydrophilicity, but also exhibited comparable mechanical strength with pure PVDF nanofiber support. After FO operation using 0.5 M NaCl as draw solution and deionized water as feed solution, the coaxial electrospun CA/PVDF composite based TFC-FO membrane achieved the following: water flux of 31.2 L m−2 h−1, remarkably lower specific reverse salt flux of 0.03 g L−1, and low structural parameter of 190 μm. Coaxial electrospinning is therefore a promising approach to fabricate high performance FO membrane whose support exhibits high porosity, mechanical stability, and hydrophilicity.
Zeweldi, HG, Limjuco, LA, Bendoy, AP, Kim, HS, Park, MJ, Shon, HK, Johnson, EM, Lee, H, Chung, WJ & Nisola, GM 2018, 'The potential of monocationic imidazolium-, phosphonium-, and ammonium-based hydrophilic ionic liquids as draw solutes for forward osmosis', Desalination, vol. 444, pp. 94-106.View/Download from: Publisher's site
© 2018 The widespread implementation of forward osmosis (FO) is highly constrained by the limited availability of suitable draw solutes (DS). Herein, monocationic hydrophilic ionic liquids (ILs) were probed as FO DS. Water (Jv), reverse solute (Js), and specific reverse solute (Js/Jv) fluxes were determined and correlated with IL properties: Van't Hoff factor (i), ionic strength, hydrated ionic radius (rH), diffusivity and membrane affinity. Most of the ILs have comparable Jv with the benchmark draw solute NaCl but their Js were significantly lower, particularly under PRO mode. Their remarkably lower Js/Jv (i.e. <0.010 ± 7.45 × 10−4 mol L−1) than NaCl (0.021 ± 0.003 mol L−1) validates their potential use as FO DS. Tetraethylammonium bromide ([N2222]Br) is the most suitable IL DS due to its high π high ionic strength, small rH, least membrane permeability (B = 0.14 L m−2 h−1) and lowest Js/Jv = 0.004 ± 5.53 × 10−4 mol L−1. Moreover, [N2222]Br effectively desalinated seawater (0.6 M NaCl). It is thermally stable and can be effectively regenerated through direct contact membrane distillation. The final permeated water had only trace [N2222]Br, which is safe for consumption as confirmed by in vitro toxicity tests. These results demonstrate that certain ILs like [N2222]Br can be identified as suitable draw solutes for FO desalination process.
Ali, SM, Kim, JE, Phuntsho, S, Jang, A, Choi, JY & Shon, HK 2018, 'Forward osmosis system analysis for optimum design and operating conditions.', Water research, vol. 145, pp. 429-441.View/Download from: Publisher's site
Low energy consumption and less fouling propensity of forward osmosis (FO) processes have been attractive as a promising water filtration technology. The performance of this process is however significantly influenced by its operating conditions. Moreover, these operating parameters have both favourable and adverse effects on its performance. Therefore, it is very important to optimize its performance for efficient and economic operation. This study aims to develop a software to analyze a full-scale FO system for optimum performance. A comprehensive theoretical framework was developed to estimate the performance of FO system. Analysis results were compared with the experimental results to validate the models. About 5% deviation of simulation results and the experimental findings shows a very good agreement between them. A novel optimization algorithm was then developed to estimate the minimum required draw solution (DS) inlet flowrate and the number of elements in a pressure vessel to attain the design objectives (i.e. desired final DS concentration and recovery rate at a specific feed solution (FS) flowrate). A detailed parametric study was also conducted to determine the optimum operating conditions for different objectives. It showed that for a specific design objective, higher recovery rate can be achieved by increasing the DS flowrate and number of elements in a pressure vessel. In contrast, lower final concentration can be obtained by lowering the DS flowrate and increasing the number of elements. Finally, a MATLAB based software with graphical user interface was developed to make the analysis process easier and efficient.
Balathanigaimani, MS, Haider, MB, Jha, D, Kumar, R, Lee, SJ, Shim, WG, Shon, HK, Kim, SC & Moon, H 2018, 'Nanostructured Biomass Based Carbon Materials from Beer Lees for Hydrogen Storage', Journal of Nanoscience and Nanotechnology, vol. 18, no. 3, pp. 2196-2199.View/Download from: Publisher's site
The present work describes the preparation of carbon materials from beer lees and their hydrogen adsorption abilities. Activated carbons (ACs) from beer lees were prepared through chemical activation using potassium hydroxide as an activating agent. The low temperature nitrogen adsorption isotherm studies on prepared ACs were conducted at 77 K to determine their physical properties and adsorption energy distribution. The beer lees based carbons have energetically heterogeneous surfaces and high surface area ranging from 1927–2408 m2/g. ACs prepared in this study show the gravimetric hydrogen adsorption capacity of 2.43–2.92 wt% depending on their physical properties
Dorji, P, Choi, J, Kim, DI, Phuntsho, S, Hong, S & Shon, HK 2018, 'Membrane capacitive deionisation as an alternative to the 2nd pass for seawater reverse osmosis desalination plant for bromide removal', Desalination, vol. 433, pp. 113-119.View/Download from: Publisher's site
© 2018 Elsevier B.V. Most Australian surface and ground waters have relatively high concentration of bromide between 400 and 8000 μg/L and even higher concentration in seawater between 60,000–78,000 μg/L. Although bromide is not regulated, even at low concentrations of 50–100 μg/L, it can lead to the formation of several types of harmful disinfection by-products (DBPs) during the disinfection process. One of the major concerns with brominated DBPs is the formation of bromate (BrO3−), a serious carcinogen that is formed when water containing a high concentration of bromide is disinfected. As a result, bromate is highly regulated in Australian water standards with the maximum concentration of 20 μg/L in the drinking water. Since seawater reverse osmosis (SWRO) desalination plays an important role in augmenting fresh water supplies in Australia, SWRO plants in Australia usually adopt 2nd pass brackish water reverse osmosis (BWRO) for effective bromide removal, which is not only energy-intensive to operate but also has higher capital cost. In this study, we evaluated the feasibility of membrane capacitive deionisation (MCDI) as one of the alternatives to the 2nd pass BWRO for effective bromide removal in a more energy efficient way.
Kim, DI, Gwak, G, Dorji, P, He, D, Phuntsho, S, Hong, S & Shon, H 2018, 'Palladium Recovery through Membrane Capacitive Deionization from Metal Plating Wastewater', ACS Sustainable Chemistry and Engineering, vol. 6, no. 2, pp. 1692-1701.View/Download from: Publisher's site
© 2017 American Chemical Society. The potential application of membrane capacitive deionization (MCDI) for recovery of palladium (Pd) ions from catalyst solution wastewater generated from the plating industry was investigated in this study. Several major issues were explored in this work to verify the suitability of MCDI for Pd recovery from a practical perspective: adsorption and desorption efficiencies, desorption mechanisms into high concentration of Pd concentrate, and its sustainability in long-term operation. The lab-scale MCDI operation achieved satisfactory and highly competitive Pd removal (99.07-99.94% removal with 1.42-1.52 of Pd selectivity over ammonium ions) showing that Pd can be effectively collected from plating industry wastewater. A high concentration of Pd concentrate (64.77 and 919.44 mg/L of Pd from the 10 and 100 mg/L Pd containing catalyst solution, respectively) was obtained through successive five operation cycles of adsorption/desorption phases. However, it is significant to note that the desorption efficiency was inversely proportional to the concentration of Pd concentrate which is likely due to the Pd ions discharged from carbon electrode toward Pd solution against the enhanced concentration gradient. The long-term operation results suggest that scaling could reduce the MCDI efficiency during Pd recovery (0.17% decrease in Pd removal for every cycle on average) and hence may require an adequate electrode cleaning regime.
Kim, JE, Phuntsho, S, Ali, SM, Choi, JY & Shon, HK 2018, 'Forward osmosis membrane modular configurations for osmotic dilution of seawater by forward osmosis and reverse osmosis hybrid system.', Water research, vol. 128, pp. 183-192.View/Download from: Publisher's site
This study evaluates various options for full-scale modular configuration of forward osmosis (FO) process for osmotic dilution of seawater using wastewater for simultaneous desalination and water reuse through FO-reverse osmosis (RO) hybrid system. Empirical relationship obtained from one FO membrane element operation was used to simulate the operational performances of different FO module configurations. The main limiting criteria for module operation is to always maintain the feed pressure higher than the draw pressure throughout the housing module for safe operation without affecting membrane integrity. Experimental studies under the conditions tested in this study show that a single membrane housing cannot accommodate more than four elements as the draw pressure exceeds the feed pressure. This then indicates that a single stage housing with eight elements is not likely to be practical for safe FO operation. Hence, six different FO modular configurations were proposed and simulated. A two-stage FO configuration with multiple housings (in parallel) in the second stage using same or larger spacer thickness reduces draw pressure build-up as the draw flow rates are reduced to half in the second stage thereby allowing more than four elements in the second stage housing. The loss of feed pressure (pressure drop) and osmotic driving force in the second stage are compensated by operating under the pressure assisted osmosis (PAO) mode, which helps enhance permeate flux and maintains positive pressure differences between the feed and draw chamber. The PAO energy penalty is compensated by enhanced permeate throughput, reduced membrane area, and plant footprint. The contribution of FO/PAO to total energy consumption was not significant compared to post RO desalination (90%) indicating that the proposed two-stage FO modular configuration is one way of making the FO full-scale operation practical for FO-RO hybrid system.
Kim, JE, Phuntsho, S, Chekli, L, Choi, JY & Shon, HK 2018, 'Environmental and economic assessment of hybrid FO-RO/NF system with selected inorganic draw solutes for the treatment of mine impaired water', Desalination, vol. 429, pp. 96-104.View/Download from: Publisher's site
© 2017 Elsevier B.V. A hybrid forward osmosis (FO) and reverse osmosis (RO)/nanofiltration (NF) system in a closed-loop operation with selected draw solutes was evaluated to treat coal mine impaired water. This study provides an insight of selecting the most suitable draw solution (DS) by conducting environmental and economic life cycle assessment (LCA). Baseline environmental LCA showed that the dominant components to energy use and global warming are the DS recovery processes (i.e. RO or NF processes) and FO membrane materials, respectively. When considering the DS replenishment in FO, the contribution of chemical use to the overall global warming impact was significant for all hybrid systems. Furthermore, from an environmental perspective, the FO-NF hybrid system with Na 2 SO 4 shows the lowest energy consumption and global warming with additional considerations of final product water quality and FO brine disposal. From an economic perspective, the FO-NF with Na 2 SO 4 showed the lowest total operating cost due to its lower DS loss and relatively low solute cost. In a closed-loop system, FO-NF with NaCl and Na 2 SO 4 had the lowest total water cost at optimum NF recovery rates of 90 and 95%, respectively. FO-NF with Na 2 SO 4 had the lowest environmental and economic impacts. Overall, draw solute performances and cost in FO and recovery rate in RO/NF play a crucial role in determining the total water cost and environmental impact of FO hybrid systems in a closed-loop operation.
Kim, S, Piao, G, Han, DS, Shon, HK & Park, H 2018, 'Solar desalination coupled with water remediation and molecular hydrogen production: A novel solar water-energy nexus', Energy and Environmental Science, vol. 11, no. 2, pp. 344-353.View/Download from: Publisher's site
© 2018 The Royal Society of Chemistry. A novel sunlight-water-energy nexus technology is presented that combines the photoelectrocatalytic (PEC) desalination of saline water and desalination-driven wastewater remediation coupled with the production of molecular hydrogen (H2) from water. To accomplish this, morphologically tailored TiO2 nanorod (TNR) and hydrogen-treated TNR (H-TNR) array photoanodes are placed in an anode cell and Pt foils are located in a cathode cell, while a middle cell containing saline water (0.17 M NaCl) faces these cells through anion and cation exchange membranes, respectively. Upon irradiation by simulated sunlight (AM 1.5G, 100 mW cm-2), the photogeneration of charge carriers initiates the transport of chloride and sodium in the middle cell to the anode and cathode cells, respectively, leading to the desalination of saline water. The chloride in the anode cell is converted to reactive chlorine species (RCS), which effectively decompose urea to N2 as a primary product (>80%), while the sodium in the cathode cell accelerates the H2 production from water with a Faradaic efficiency of ∼80%. The PEC performance of the H-TNR photoanodes is superior to that of the TNR in the anodic and cathodic processes because of the reduced charge transfer resistance and sub-nanosecond charge transfer kinetics (∼0.19 ns), leading to a specific energy consumption of 4.4 kW h m-3 for 50% desalination, with an energy recovery of ∼0.8 kW h m-3. The hybrid system is found to operate for a period of ∼60 h with natural seawater, and virtually all the photoanodes are shown to be capable of driving the hybrid process. Although tested as a proof-of-concept, the present technology opens up a novel field involving a sunlight-water-energy nexus, promising high efficiency desalination and the desalination-driven remediation of water with simultaneous H2 production.
Kook, S, Lee, C, Thanh, TN, Lee, J, Shon, HK & Kim, IS 2018, 'Serially connected forward osmosis membrane elements of pressure-assisted forward osmosis-reverse osmosis hybrid system: Process performance and economic analysis', DESALINATION, vol. 448, pp. 1-12.View/Download from: Publisher's site
Lee, S, Kim, Y, Park, J, Shon, HK & Hong, S 2018, 'Treatment of medical radioactive liquid waste using Forward Osmosis (FO) membrane process', Journal of Membrane Science, vol. 556, pp. 238-247.View/Download from: Publisher's site
© 2018 Elsevier B.V. The use of forward osmosis (FO) for concentrating radioactive liquid waste from radiation therapy rooms in hospitals was systematically investigated in this study. The removal of natural and radioactive iodine using FO was first investigated with varying pHs and draw solutions (DSs) to identify the optimal conditions for FO concentration. Results showed that FO had a successful rejection rate for both natural and radioactive iodine (125I) of up to 99.3%. This high rejection rate was achieved at a high pH, mainly due to electric repulsion between iodine and membrane. Higher iodine removal by FO was also attained with a DS that exhibits a reverse salt flux (RSF) adequate to hinder iodine transport. Following this, actual radioactive medical liquid waste was collected and concentrated using FO under these optimal conditions. The radionuclides in the medical waste (131I) were removed effectively, but the water recovery rate was limited due to severe membrane fouling. To enhance the recovery rate, hydraulic washing was applied, but this had only limited success due to combined organic-inorganic fouling of the FO membrane. Finally, the effect of FO concentration on the reduction of septic tank volume was simulated as a function of recovery rate. To our knowledge, this study is the first attempt to explore the potential of FO technology for treating radioactive waste, and thus could be expanded to the dewatering of the radioactive liquid wastes from a variety of sources, such as nuclear power plants.
Liyanaarachchi, S, Muthukumaran, S, Kaiser, J, Rogers, P, Shu, L, Shon, HK & Jegatheesan, V 2018, 'Computing the effective diffusion coefficient of solutes in a multi-salts solutions during forward osmosis (FO) membrane filtration: Experiments and mathematical modelling.', Journal of environmental management, vol. 214, pp. 215-223.View/Download from: Publisher's site
Diffusion coefficient of solutes through a porous membrane media is different from diffusion coefficient through a free homogenous media. Porosity, tortuosity and the thickness of the membrane significantly affect the diffusion through a specific thickness of a membrane and therefore it is termed as effective diffusion coefficient (Deff) which is lower than the actual diffusion coefficient, D. The Deff of single or dual solutes through a porous membrane layer are well documented but not for multiple salts. Therefore, in this study, single, dual and multiple salt mixtures were passed through a flat sheet cellulose triacetate Forward Osmosis (FO) membrane to obtain a semi-empirical relationship with the Deff and its water flux. This will allow computing the structural coefficient of FO membranes. Research community have spent tremendous efforts in membrane modification to reduce the structural coefficient to improve FO process efficiency. Our finding suggests that optimising the draw solution chemistry can achieve this goal.
Nuruzzaman, M, Liu, Y, Rahman, MM, Naidu, R, Naidu, R, Dharmarajan, R, Shon, HK & Woo, YC 2018, 'Core-Shell Interface-Oriented Synthesis of Bowl-Structured Hollow Silica Nanospheres Using Self-Assembled ABC Triblock Copolymeric Micelles.', Langmuir : the ACS journal of surfaces and colloids, vol. 34, no. 45, pp. 13584-13596.View/Download from: Publisher's site
Hollow porous silica nanospheres (HSNs) are emerging classes of cutting-edge nanostructured materials. They have elicited much interest as carriers of active molecule delivery due to their amorphous chemical structure, nontoxic nature, and biocompatibility. Structural development with hierarchical morphology is mostly required to obtain the desired performance. In this context, large through-holes or pore openings on shells are desired so that the postsynthesis loading of active-molecule onto HSNs via a simple immersion method can be facilitated. This study reports the synthesis of HSNs with large through-holes or pore openings on shells, which are subsequently termed bowl-structured hollow porous silica nanospheres (BHSNs). The synthesis of BHSNs was mediated by the core-shell interfaces of the core-shell corona-structured micelles obtained from a commercially available ABC triblock copolymer (polystyrene- b-poly(2-vinylpyridine)- b-poly(ethylene oxide) (PS-P2VP-PEO)). In this synthesis process, polymer@SiO2 composite structure was formed because of the deposition of silica (SiO2) on the micelles' core. The P2VP block played a significant role in the hydrolysis and condensation of the silica precursor, i.e., tetraethylorthosilicate (TEOS) and then maintaining the shell's growth. The PS core of the micelles built the void spaces. Transmission electron microscopy (TEM) images revealed a spherical hollow structure with an average particle size of 41.87 ± 3.28 nm. The average diameter of void spaces was 21.71 ± 1.22 nm, and the shell thickness was 10.17 ± 1.68 nm. According to the TEM image analysis, the average large pore was determined to be 15.95 nm. Scanning electron microscopy (SEM) images further confirmed the presence of large single pores or openings in shells. These were formed as a result of the accumulated ethanol on the PS core acting to prevent the growth of silica.
Sahebi, S, Shon, HK, Phuntsho, S & Ramavandi, B 2018, 'Fabricating robust thin film composite membranes reinforced on woven mesh backing fabric support for pressure assisted and forward osmosis: A dataset.', Data in Brief, vol. 21, pp. 364-370.View/Download from: Publisher's site
The data presented in this paper are produced as part of the original research article entitled "Thin-film composite membrane on a compacted woven backing fabric for pressure assisted osmosis" (Sahebi et al., 2017). This article describes how to fabricate a defect free membrane for forward osmosis (FO) and pressure assisted osmosis (PAO) on the woven mesh backing fabric support. Casting polymer on backing fabric support may limit the interfacial polyemirization due to wrinkled membrane surface. This paper presents data obtained from two different backing fabrics used as support for fabrication of thin film composite FO membrane. Backing fabric support were woven polyester mesh with different opening size. The data include the characterization of the intrinsic properties of the membrane samples, SEM and their performance under FO process. The structural parameters (S value) of the substrate were computed from thickness and porosity of the substrates. Thin film composite (TFC) membrane achieved a water flux of 8.1 L m2 h-1 in FO process and 37 L m2 h-1 using 0.5 M NaCl as draw solution (DS) and deionised (DI) water as the feed solution (FS) when applied hydraulic pressure was 10 bar.
Song, Y-C, Kim, M, Shon, H, Jegatheesan, V & Kim, S 2018, 'Modeling methane production in anaerobic forward osmosis bioreactor using a modified anaerobic digestion model No. 1', BIORESOURCE TECHNOLOGY, vol. 264, pp. 211-218.View/Download from: Publisher's site
Volpin, F, Chekli, L, Phuntsho, S, Cho, J, Ghaffour, N, Vrouwenvelder, JS & Shon, HK 2018, 'Simultaneous phosphorous and nitrogen recovery from source separated urine: A novel application for fertiliser drawn forward osmosis', CHEMOSPHERE, vol. 203, pp. 482-489.View/Download from: Publisher's site
Volpin, F, Fons, E, Chekli, L, Kim, JE, Jang, A & Shon, HK 2018, 'Hybrid forward osmosis-reverse osmosis for wastewater reuse and seawater desalination: Understanding the optimal feed solution to minimise fouling', Process Safety and Environmental Protection, vol. 117, pp. 523-532.View/Download from: Publisher's site
© 2018 Institution of Chemical Engineers To enhance the seawater desalination energy efficiency forward osmosis – reverse osmosis (FO-RO) hybrid system has recently been developed. In this process, the FO “pre-treatment” step is designed to use seawater (SW) as draw solution to filter the wastewater (WW) while reducing the seawater osmotic pressure. Thereby reducing the operating pressure of the RO to desalinate the diluted SW. However, membrane fouling is a major issue that needs to be addressed. Proper selection of suitable WWs is necessary before proceeding with large-scale FO-RO desalination plants. In this study, long-term experiments were carried out, using state-of-the-art FO membrane, using real WW and SW solutions. A combination of water flux modelling and membrane characterisation were used to assess the degree of membrane fouling and the impact on the process performance. Initial water flux as high as 22.5 Lm−2 h−1 was observed when using secondary effluent. It was also found that secondary effluent causes negligible flux decline. On the other hand, biologically treated wastewater and primary effluent caused mild and severe flux decline respectively (25% and 50% of flux decline after 80 hours, compared to no-fouling conditions). Ammonia leakage to the diluted seawater was also measured, concluding that, if biologically treated wastewater is used as feed, the final NH4+ concentration in the draw is likely to be negligible.
Wang, C, Gao, B, Zhao, P, Yue, Q, Shon, HK & Yang, S 2018, 'The forward osmosis application: Using the secondary effluent as makeup water for cooling water dilution', Desalination and Water Treatment, vol. 105, pp. 1-10.View/Download from: Publisher's site
© 2018 Desalination Publications. All rights reserved. This study evaluated the feasibility of using the secondary effluent as makeup water for cooling water. The secondary effluent and the simulated cooling water were used as feed solution (FS) and draw solution (DS) in FO process. Ammonium bicarbonate was added into the simulated cooling water to promote the osmotic pressure. The tests were studied under different membrane orientations, temperatures and flow rates using both TFC-FO and CTA-FO membranes, and determined in terms of water flux, the permeate recovery and membrane fouling. The considerable permeate recovery (18.9% at 20 h) and reversible membrane fouling indicated that the feasibility of using FO for cooling water reuse. CTA- and TFC-PRO modes had higher initial water flux, but more significant flux decline compared to CTA- and TFC-FO modes. The optimal conditions were determined to be 25°C and 17.0 cm/s in which the water flux was highest. The results showed that water flux did not increase with the temperature when it was above than 30°C. The same situation occurred at the cross flow velocity above than 17 cm/s. The fouling of TFC membrane was serious after running 20 h, but it could be cleaned well by 1 h simple surface flushing and the water flux could restore nearly 93.8%.
Chekli, L, Pathak, N, Kim, Y, Phuntsho, S, Li, S, Ghaffour, N, Leiknes, T & Shon, HK 2018, 'Combining high performance fertiliser with surfactants to reduce the reverse solute flux in the fertiliser drawn forward osmosis process.', Journal of environmental management, vol. 226, pp. 217-225.View/Download from: Publisher's site
Solutions to mitigate the reverse diffusion of solutes are critical to the successful commercialisation of the fertiliser drawn forward osmosis process. In this study, we proposed to combine a high performance fertiliser (i.e., ammonium sulfate or SOA) with surfactants as additives as an approach to reduce the reverse diffusion of ammonium ions. Results showed that combining SOA with both anionic and non-ionic surfactants can help in reducing the reverse salt diffusion by up to 67%. We hypothesised that, hydrophobic interactions between the surfactant tails and the membrane surface likely constricted membrane pores resulting in increased rejection of ions with large hydrated radii such as SO42-. By electroneutrality, the rejection of the counter ions (i.e., NH4+) also therefore subsequently improved. Anionic surfactant was found to further decrease the reverse salt diffusion due to electrostatic repulsions between the surfactant negatively-charged heads and SO42-. However, when the feed solution contains cations with small hydrated radii (e.g., Na+); it was found that NH4+ ions can be substituted in the DS to maintain its electroneutrality and thus the diffusion of NH4+ to the feed solution was increased.
Fortunato, L, Pathak, N, Ur Rehman, Z, Shon, H & Leiknes, TO 2018, 'Real-time monitoring of membrane fouling development during early stages of activated sludge membrane bioreactor operation', Process Safety and Environmental Protection, vol. 120, pp. 313-320.View/Download from: Publisher's site
© 2018 Institution of Chemical Engineers Non-invasive analysis and a final destructive analysis were employed to study the fouling formation during the initial days of AS-MBR operation. The fouling layer development was quantified in-situ non-invasively with Optical Coherence Tomography (OCT). The increase in biomass thickness was related to the transmembrane pressure (TMP) and to the increase in concentration of soluble microbial products (SMP) in the reactor The OCT non-destructive analysis allowed normalizing the final autopsy values for the amount of biomass deposited on the membrane. After 8 days of operation, the cake layer presented a biomass activity of 400 pg/mm3 of intra-ATP and EPS concentration of 9.8 mg/ mm3. The microbial community analysis of sludge and biofouling on the membrane surface revealed the abundance of Proteobacteria.
Pathak, N, Fortunato, L, Li, S, Chekli, L, Phuntsho, S, Ghaffour, N, Leiknes, T & Shon, HK 2018, 'Evaluating the effect of different draw solutes in a baffled osmotic membrane bioreactor-microfiltration using optical coherence tomography with real wastewater.', Bioresource technology, vol. 263, pp. 306-316.View/Download from: Publisher's site
This study investigated the performance of an integrated osmotic and microfiltration membrane bioreactor for real sewage employing baffles in the reactor. To study the biofouling development on forward osmosis membranes optical coherence tomography (OCT) technique was employed. On-line monitoring of biofilm growth on a flat sheet cellulose triacetate forward osmosis (CTA-FO) membrane was conducted for 21 days. Further, the process performance was evaluated in terms of water flux, organic and nutrient removal, microbial activity in terms of soluble microbial products (SMP) and extracellular polymeric substance (EPS), and floc size. The measured biofouling layer thickness was in the order sodium chloride (NaCl) > ammonium sulfate (SOA) > potassium dihydrogen phosphate (KH2PO4). Very high organic removal (96.9 ± 0.8%) and reasonably good nutrient removal efficiency (85.2 ± 1.6% TN) was achieved. The sludge characteristics and biofouling layer thickness suggest that less EPS and higher floc size were the governing factors for less fouling.
Pathak, N, Li, S, Kim, Y, Chekli, L, Phuntsho, S, Jang, A, Ghaffour, N, Leiknes, T & Shon, HK 2018, 'Assessing the removal of organic micropollutants by a novel baffled osmotic membrane bioreactor-microfiltration hybrid system.', Bioresource technology, vol. 262, pp. 98-106.View/Download from: Publisher's site
A novel approach was employed to study removal of organic micropollutants (OMPs) in a baffled osmotic membrane bioreactor-microfiltration (OMBR-MF) hybrid system under oxicanoxic conditions. The performance of OMBR-MF system was examined employing three different draw solutes (DS), and three model OMPs. The highest forward osmosis (FO) membrane rejection was attained with atenolol (100%) due to its higher molar mass and positive charge. With inorganic DS caffeine (94-100%) revealed highest removal followed by atenolol (89-96%) and atrazine (16-40%) respectively. All three OMPs exhibited higher removal with organic DS as compared to inorganic DS. Significant anoxic removal was observed for atrazine under very different redox conditions with extended anoxic cycle time. This can be linked with possible development of different microbial consortia responsible for diverse enzymes secretion. Overall, the OMBR-MF process showed effective removal of total organic carbon (98%) and nutrients (phosphate 97% and total nitrogen 85%), respectively.
Volpin, F, Gonzales, RR, Lim, S, Pathak, N, Phuntsho, S & Shon, HK 2018, 'GreenPRO: A novel fertiliser-driven osmotic power generation process for fertigation', DESALINATION, vol. 447, pp. 158-166.View/Download from: Publisher's site
Duong, HC, Chuai, D, Woo, YC, Shon, HK, Nghiem, LD & Sencadas, V 2018, 'A novel electrospun, hydrophobic, and elastomeric styrene-butadiene-styrene membrane for membrane distillation applications', Journal of Membrane Science, vol. 549, pp. 420-427.View/Download from: Publisher's site
© 2017 In this study, a novel hydrophobic, microporous membrane was fabricated from styrene-butadiene-styrene (SBS) polymer using electrospinning and evaluated for membrane distillation applications. Compared to a commercially available polytetrafluoroethylene (PTFE) membrane, the SBS membrane had larger membrane pore size and fiber diameter and comparable membrane porosity. The fabricated SBS showed slightly lower water flux than the PTFE membrane because it was two times thicker. However, the SBS membrane had better salt rejection and most importantly could be fabricated via a simple process. The SBS membrane was also more hydrophobic than the reference PTFE membrane. In particular, as temperature of the reference water liquid increased to 60 °C, the SBS membrane remained hydrophobic with a contact angle of 100° whereas the PTFE became hydrophilic with a contact angle of less than 90°. The hydrophobic membrane surface prevented the intrusion of liquid into the membrane pores, thus improving the salt rejection of the SBS membrane. In addition, the SBS membrane had superior mechanical strength over the PTFE membrane. Using the SBS membrane, stable water flux was achieved throughout an extended MD operation period of 120 h to produce excellent quality distillate (over 99.7% salt rejection) from seawater.
Chekli, L, Corjon, E, Tabatabai, SAA, Naidu, G, Tamburic, B, Park, SH & Shon, HK 2017, 'Performance of titanium salts compared to conventional FeCl3 for the removal of algal organic matter (AOM) in synthetic seawater: Coagulation performance, organic fraction removal and floc characteristics.', Journal of Environmental Management, vol. 201, pp. 28-36.View/Download from: Publisher's site
During algal bloom periods, operation of seawater reverse osmosis (SWRO) pretreatment processes (e.g. ultrafiltration (UF)) has been hindered due to the high concentration of algal cells and algal organic matter (AOM). The present study evaluated for the first time the performance of titanium salts (i.e. titanium tetrachloride (TiCl4) and polytitanium tetrachloride (PTC)) for the removal of AOM in seawater and results were compared with the conventional FeCl3 coagulant. Previous studies already demonstrated that titanium salts not only provide a cost-effective alternative to conventional coagulants by producing a valuable by-product but also minimise the environmental impact of sludge production. Results from this study showed that both TiCl4 and PTC achieved better performance than FeCl3 in terms of turbidity, UV254 and dissolved organic carbon (DOC) removal at similar coagulant dose. Liquid chromatography - organic carbon detection (LC-OCD) was used to determine the removal of AOM compounds based on their molecular weight (MW). This investigation revealed that both humic substances and low MW organics were preferentially removed (i.e. up to 93% removal) while all three coagulants showed poorer performance for the removal of high MW biopolymers (i.e. less than 50% removal). The detailed characterization of flocs indicated that both titanium coagulants can grow faster, reach larger size and present a more compact structure, which is highly advantageous for the design of smaller and more compact mixing and sedimentation tanks. Both titanium coagulants also presented a higher ability to withstand shear force, which was related to the higher amount of DOC adsorbed with the aggregated flocs. Finally, TiCl4 had a better recovery after breakage suggesting that charge neutralization may be the dominant mechanism for this coagulant, while the lower recovery of both PTC and FeCl3 indicated that sweep flocculation is also a contributing mechanism for the coagulation of AOM...
Lim, S, Park, MJ, Phuntsho, S, Tijing, LD, Nisola, GM, Shim, WG, Chung, WJ & Shon, HK 2017, 'Dual-layered nanocomposite substrate membrane based on polysulfone/graphene oxide for mitigating internal concentration polarization in forward osmosis', Polymer, vol. 110, pp. 36-48.View/Download from: Publisher's site
© 2016 Elsevier Ltd A novel thin-film composite (TFC) forward osmosis (FO) membrane with dual-layered substrate membrane was fabricated by a double-blade casting technique using different polysulfone (PSf) concentrations for top (15 wt%) and bottom (7 wt%) substrate layers. Graphene oxide (GO) was incorporated in the substrate layer, and the dual casting approach resulted in a membrane support with a highly porous bottom structure and a dense top skin layer on which the polyamide active layer was effectively formed. The dual-layered TFC PSf/GO membrane (TFC-PSf d GO) exhibited high water permeability, and ion selectivity was enhanced by the presence of well dispersed hydrophilic GO in the PSf substrate. The TFC-PSf d GO also exhibited the lowest specific reverse salt flux (J s /J v = 0.19 g L -1 ) and a more favorable structural parameter (S = 130 μm) compared to GO-free membranes. Using deionized water as feed solution and 1 M NaCl as draw solution (DS), TFC-PSf d GO had J v = 33.8 L m −2 h −1 and J s = 6.9 g −2 h −1 under AL-FS mode, and J v = 61.5 L m −2 h −1 and J s = 14.0 g −2 h −1 under AL-DS mode. The potential of TFC-PSf d GO for commercial application was further evaluated by fabricating it with a fabric backing support (denoted as TFC-PSf d GO f ). Compared to TFC-PSf d GO, TFC-PSf d GO f exhibited only 14% decline in its water flux. The overall results reveal that, fabrication of TFC substrate membrane via dual-blade casting approach along with GO incorporation produced high-performance TFC FO membranes which likely reduced the internal concentration polarization effects.
Ren, J, Tijing, LD & Shon, HK 2017, '"Robbing behavior" and re-immobilization of nanoscale zero-valent iron (nZVI) onto electrospun polymeric nanofiber mats for trichloroethylene (TCE) remediation', SEPARATION AND PURIFICATION TECHNOLOGY, vol. 189, pp. 375-381.View/Download from: Publisher's site
Nanoscale zero-valent iron (nZVI) has been widely used for the reduction of halogenated organics and heavy metals in the groundwater. However, individual nZVI particles are mobile and prone to aggregate, thereby reducing the reaction sites exposed to contaminants. Electrospun polymer nanofiber mat is an ideal carrier to immobilize and distribute nZVI particles after its merits of high specific area, size-controllable and material-compatible properties. In this study, nZVI particles were loaded onto the polyacrylic acid (PAA)-polyvinyl alcohol (PVA) electrospun nanofiber mats with different PAA/PVA ratios. The results indicate that mat with the PAA/PVA ratio of 3:1 loaded the most nZVI particles (∼48 wt%) and had the highest removals to methylene blue at 94% and Cu (II) ions at 84% respectively. The nZVI-loaded electrospun nanofiber mat has promising application for the groundwater contaminants mitigation.
Ren, J, Woo, YC, Yao, M, Tijing, LD & Shon, HK 2017, 'Enhancement of nanoscale zero-valent iron immobilization onto electrospun polymeric nanofiber mats for groundwater remediation', Process Safety and Environmental Protection, vol. 112, no. Part B, pp. 200-208.View/Download from: Publisher's site
© 2017 Institution of Chemical Engineers A new approach that combines nanoscale zero-valent iron (nZVI) with electrospinning technology has been put forward to avoid nZVI agglomeration and a secondary pollution. In this study, to enhance the immobilization of nZVI particles onto the polyacrylic acid (PAA)/polyvinyl alcohol (PVA) electrospun nanofiber mat, mats (M1, M2 and M3) with different PAA/PVA mass ratios (1:1, 2:1 and 3:1) were tested for the immobilization of nZVI particles and their performance of removing contaminants. The results indicate that M3 immobilized the most nZVI particles (48.4 wt% on the mat, ∼2.5 times the figure for previous study) and had the highest removals to methylene blue and Cu(II) ions at 94% and 83.6% respectively, resulting from more free carboxylic groups available on the cross-linked nanofibers as well as a higher porosity into the mat. Therefore, increasing the PAA/PVA ratio is effective to boost the performance of nZVI–PAA/PVA electrospun nanofiber mat, which has a great potential for the application of nZVI-targeted contaminants remediation.
Sahebi, S, Phuntsho, S, Tijing, L, Han, G, Han, DS, Abdel-Wahab, A & Shon, HK 2017, 'Thin-film composite membrane on a compacted woven backing fabric for pressure assisted osmosis', Desalination, vol. 406, pp. 98-108.View/Download from: Publisher's site
© 2016 Elsevier B.V.The water flux in forward osmosis (FO) process declines substantially when the draw solution (DS) concentration reaches closer to the point of osmotic equilibrium with the feed solution (FS). Using external hydraulic pressure alongside the osmotic driving force in the pressure assisted osmosis (PAO) has been found effective in terms of enhancing water flux and even potentially diluting the DS beyond osmotic equilibrium. The net gain in water flux due to the applied pressure in the PAO process closely depends on the permeability of the FO membrane. The commercial flat sheet cellulose triacetate (CTA) FO membrane has low water permeability and hence the effective gain in water flux in the PAO process is low. In this study, a high performance thin film composite membrane was developed especially for the PAO process through casting polyethersulfone (PES) polymer solution on a compacted woven fabric mesh support followed by interfacial polymerisation for polyamide active layer. This PAO membrane possesses a water flux of 37Lm2 h-1 using 0.5M NaCl as DS and deionised water as the feed at an applied hydraulic pressure of 10bar. Besides, the membrane was able to endure the external hydraulic pressure required for the PAO process owing to the embedded backing fabric support. While the membranes with low structural parameters are essential for higher water flux, this study shows that for PAO process, polymeric membranes with larger structural parameters may not be suitable for PAO. They generally resulted in compaction and poor mechanical strength to withstand hydraulic pressure.
Woo, YC, Chen, Y, Tijing, LD, Phuntsho, S, He, T, Choi, JS, Kim, SH & Shon, HK 2017, 'CF4 plasma-modified omniphobic electrospun nanofiber membrane for produced water brine treatment by membrane distillation', Journal of Membrane Science, vol. 529, pp. 234-242.View/Download from: Publisher's site
This study describes the development and performance of an omniphobic poly(vinylidene fluoride) (PVDF) membrane by electrospinning and CF 4 plasma surface modification for air gap membrane distillation (AGMD). The effect of different duration of plasma treatment on the nanofiber membrane cha racteristics was investigated. The AGMD performance of the membranes was evaluated using real reverse osmosis (RO) brine produced from coal seam gas (CSG) water that was added with low surface tension liquid (surfactant) as feed solution. Results indicated the formation of new CF 2 -CF 2 and CF 3 bonds after plasma treatment, which lowered the surface energy of the membrane, providing omniphobic property, as indicated by its wetting resistance to different low surface tension liquids such as methanol, mineral oil and ethylene glycol. Though no appreciative changes in morphology of the membrane were observed after plasma treatment, optimal treatment condition of 15 min (i.e., P/CF-15 membrane) exhibited lotus effect membrane surface with increased liquid entry pressure of 187 kPa compared to 142 kPa for neat membrane. AGMD performance showed stable normalized flux (initial flux of 15.3 L/m 2 h) and rejection ratio (100%) for P/CF-15 even with the addition of up to 0.7 mM sodium dodecyl sulfate surfactant to the RO brine from CSG produced water feed, while commercial PVDF membrane suffered membrane wetting after 0.3 mM of surfactant addition. Based on the results, the present omniphobic membrane has good potential for producing clean water from challenging waters containing high salinity and organic contaminants.
Woo, YC, Tijing, LD, Park, MJ, Yao, M, Choi, JS, Lee, S, Kim, SH, An, KJ & Shon, HK 2017, 'Electrospun dual-layer nonwoven membrane for desalination by air gap membrane distillation', Desalination, vol. 403, pp. 187-198.View/Download from: Publisher's site
© 2015 Elsevier B.V. In the present study, dual-layer nanofiber nonwoven membranes were prepared by a facile electrospinning technique and applied for desalination by air gap membrane distillation (AGMD). Neat single and dual-layer nanofiber membranes composed of a hydrophobic polyvinylidene fluoride-co-hexafluoropropylene (PH) top layer with different supporting hydrophilic layer made of either polyvinyl alcohol (PVA), nylon-6 (N6), or polyacrylonitrile (PAN) nanofibers were fabricated with and without heat-press post-treatment. Surface characterization showed that the active layer (i.e., PH) of all electrospun nanofiber membranes (ENMs) exhibited a rough, highly porous (>80% porosity), and hydrophobic surface (CA>140°), while the other side was hydrophilic (CA<90°) with varying porosity. Heat-pressing the membrane resulted to thinner thickness (from >129μm to <100μm) and smaller pore sizes (<0.27μm). The AGMD experiments in a co-current flow set-up were carried out with constant inlet temperatures at the feed and permeate streams of 60±1.5 and 20±1.5°C, respectively. The AGMD module had a membrane area of 21cm2 and the thickness of the air gap was 3mm. The neat single and dual-layer ENMs showed a water permeate flux of about 10.9-15.5L/m2 h (LMH) using 3.5wt.% NaCl solution as feed, which was much higher than that of a commercial PVDF membrane (~5LMH). The provision of a hydrophilic layer at the bottom layer enhanced the AGMD performance depending on the wettability and characteristics of the support layer. The PH/N6 dual-layer nanofiber membrane prepared under the optimum condition showed flux and salt rejection of 15.5LMH and 99.2%, respectively, which has good potential for AGMD application.
Yao, M, Woo, YC, Tijing, LD, Cesarini, C & Shon, HK 2017, 'Improving nanofiber membrane characteristics and membrane distillation performance of heat-pressed membranes via annealing post-treatment', Applied Sciences, vol. 7, no. 1, pp. 1-11.View/Download from: Publisher's site
© 2017 by the authors. Electrospun membranes are gaining interest for use in membrane distillation (MD) dueto their high porosity and interconnected pore structure however, they are still susceptible towetting during MD operation because of their relatively low liquid entry pressure (LEP). In thisstudy, post-treatment had been applied to improve the LEP, as well as its permeation and saltrejection efficiency. The post-treatment included two continuous procedures: heat-pressing andannealing. In this study, annealing was applied on the membranes that had been heat-pressed.It was found that annealing improved the MD performance as the average flux reached 35 L/m 2 hor LMH ( > 10% improvement of the ones without annealing) while still maintaining 99.99% saltrejection. Further tests on LEP, contact angle, and pore size distribution explain the improvementdue to annealing well. Fourier transform infrared spectroscopy and X-ray diffraction analysesof the membranes showed that there was an increase in the crystallinity of the polyvinylidenefluoride-co-hexafluoropropylene (PVDF-HFP) membrane also, peaks indicating the α phase ofpolyvinylidene fluoride (PVDF) became noticeable after annealing, indicating some βand amorphousstates of polymer were converted into the α phase. The changes were favorable for membranedistillation as the non-polar α phase of PVDF reduces the dipolar attraction force between themembrane and water molecules, and the increase in crystallinity would result in higher thermalstability. The present results indicate the positive effect of the heat-press followed by an annealingpost-treatment on the membrane characteristics and MD performance.
Chung, WJ, Torrejos, REC, Park, MJ, Vivas, EL, Limjuco, LA, Lawagon, CP, Parohinog, KJ, Lee, SP, Shon, HK, Kim, H & Nisola, GM 2017, 'Continuous lithium mining from aqueous resources by an adsorbent filter with a 3D polymeric nanofiber network infused with ion sieves', Chemical Engineering Journal, vol. 309, pp. 49-62.View/Download from: Publisher's site
© 2016 Elsevier B.V. Electrospun composite nanofiber (NF) was fabricated and employed as an adsorbent membrane filter in a continuous Li + mining process from seawater. The filter was composed of a hydrophilic polyacrylonitrile (PAN) matrix infused with lithium ion sieves (LIS) H 1.6 Mn 1.6 O 4 . Characterization of the LIS/PAN NF confirmed its favorable structural and surface properties for effective Li + adsorption. The LIS/PAN NF was mechanically suitable as a microfiltration membrane with high water flux and low pressure requirement. Breakthrough experiments at varied feed concentrations (C f ), seawater flowrates (F), and NF thicknesses (Z) revealed the dynamic adsorption behavior of the filter. The seawater residence time was most critical and must be kept ⩾0.12 min at any given C f and Z to maximize the Li + capacity of the filter. This can be conveniently achieved by adjusting the F of the process. Analogous to a packed bed system, the predictive power of nine breakthrough models were determined through non-linear regression analyses. Results reveal that bed-depth-space-time, Bohart-Adams (BA) and Thomas models adequately predicted the performance of the filter albeit BA exhibited the best agreement. Meanwhile, Wolborska failed to converge with any of the experimental results while Yoon-Nelson, Wang, Clark, dose-response, and modified dose-response were too simple to provide any meaningful information. Cycled Li + adsorption-desorption runs successfully collected and concentrated Li + in a mild acid stripping solution. After ten cycles, Li + was separated 155–1552 times more efficiently than Na + , K + , Mg 2+ and Ca 2+ . Overall results demonstrate the potential of LIS/PAN NF as an adsorbent membrane filter for continuous Li + mining from aqueous resources.
Chekli, L, Eripret, C, Park, SH, Tabatabai, SAA, Vronska, O, Tamburic, B, Kim, JH & Shon, HK 2017, 'Coagulation performance and floc characteristics of polytitanium tetrachloride (PTC) compared with titanium tetrachloride (TiCl4) and ferric chloride (FeCl3) in algal turbid water', Separation and Purification Technology, vol. 175, pp. 99-106.View/Download from: Publisher's site
© 2016 Elsevier B.V. Seasonal green algae blooms in freshwaters have raised attention on the need to develop novel effective treatment processes for the removal of algae in water. In the present study, the performance of newly developed polytitanium tetrachloride (PTC) coagulant for the removal of freshwater microalga Chlorella vulgaris has been investigated and compared with titanium tetrachloride (TiCl 4 ) coagulant and the conventional ferric chloride (FeCl 3 ) coagulant. The main benefit of using titanium-based coagulants is that the sludge produced after flocculation may be recycled into a valuable product: titanium dioxide photocatalyst. Both titanium-based coagulants achieved good flocculation over a broader pH range and coagulant dose compared to conventional FeCl 3 coagulant. All three coagulants achieved comparable performance in terms of turbidity removal (i.e. turbidity removal efficiency > 97%); although TiCl 4 performed slightly better at the lower tested dose (i.e. < 9 mg/L). Zeta potential measurements indicated that charge neutralisation may not be the sole mechanism involved in the coagulation of algae for all three coagulants. Analysis of the dynamic floc size variation during floc breakage showed no regrowth after floc breakage for the three coagulants. The flocs formed by both Ti-based coagulants were larger than those formed by FeCl 3 and also grew at a faster rate. This study indicates that Ti-based coagulants are effective and promising coagulants for algae removal in water.
Chekli, L, Kim, JE, El Saliby, I, Kim, Y, Phuntsho, S, Li, S, Ghaffour, N, Leiknes, TO & Kyong Shon, H 2017, 'Fertilizer drawn forward osmosis process for sustainable water reuse to grow hydroponic lettuce using commercial nutrient solution', Separation and Purification Technology, vol. 181, pp. 18-28.View/Download from: Publisher's site
© 2017 Elsevier B.V. This study investigated the sustainable reuse of wastewater using fertilizer drawn forward osmosis (FDFO) process through osmotic dilution of commercial nutrient solution for hydroponics, a widely used technique for growing plants without soil. Results from the bench-scale experiments showed that the commercial hydroponic nutrient solution (i.e. solution containing water and essential nutrients) exhibited similar performance (i.e., water flux and reverse salt flux) to other inorganic draw solutions when treating synthetic wastewater. The use of hydroponic solution is highly advantageous since it provides all the required macro- (i.e., N, P and K) and micronutrients (i.e., Ca, Mg, S, Mn, B, Zn and Mo) in a single balanced solution and can therefore be used directly after dilution without the need to add any elements. After long-term operation (i.e. up to 75% water recovery), different physical cleaning methods were tested and results showed that hydraulic flushing can effectively restore up to 75% of the initial water flux while osmotic backwashing was able to restore the initial water flux by more than 95%; illustrating the low-fouling potential of the FDFO process. Pilot-scale studies demonstrated that the FDFO process is able to produce the required nutrient concentration and final water quality (i.e., pH and conductivity) suitable for hydroponic applications. Coupling FDFO with pressure assisted osmosis (PAO) in the later stages could help in saving operational costs (i.e., energy and membrane replacement costs). Finally, the test application of nutrient solution produced by the pilot FDFO process to hydroponic lettuce showed similar growth pattern as the control without any signs of nutrient deficiency.
Chekli, L, Kim, Y, Phuntsho, S, Li, S, Ghaffour, N, Leiknes, T & Shon, HK 2017, 'Evaluation of fertilizer-drawn forward osmosis for sustainable agriculture and water reuse in arid regions.', Journal of environmental management, vol. 187, pp. 137-145.View/Download from: Publisher's site
The present study focused on the performance of the FDFO process to achieve simultaneous water reuse from wastewater and production of nutrient solution for hydroponic application. Bio-methane potential (BMP) measurements were firstly carried out to determine the effect of osmotic concentration of wastewater achieved in the FDFO process on the anaerobic activity. Results showed that 95% water recovery from the FDFO process is the optimum value for further AnMBR treatment. Nine different fertilizers were then tested based on their FO performance (i.e. water flux, water recovery and reverse salt flux) and final nutrient concentration. From this initial screening, ammonium phosphate monobasic (MAP), ammonium sulfate (SOA) and mono-potassium phosphate were selected for long term experiments to investigate the maximum water recovery achievable. After the experiments, hydraulic membrane cleaning was performed to assess the water flux recovery. SOA showed the highest water recovery rate, up to 76% while KH2PO4 showed the highest water flux recovery, up to 75% and finally MAP showed the lowest final nutrient concentration. However, substantial dilution was still necessary to comply with the standards for fertigation even if the recovery rate was increased.
Chen, G, Liu, R, Shon, HK, Wang, Y, Song, J, Li, XM & He, T 2017, 'Open porous hydrophilic supported thin-film composite forward osmosis membrane via co-casting for treatment of high-salinity wastewater', Desalination, vol. 405, pp. 76-84.View/Download from: Publisher's site
© 2016 High-performance thin film composite (TFC) forward osmosis (FO) membranes with a low degree of internal concentration polarization (ICP) are critical for concentrating high-salinity wastewaters. This report focuses on the preparation of TFC FO membranes via a sacrificial approach. In order to improve the FO flux, hydrophilicity and morphology of the support membrane were mainly investigated. The hydrophilicity of the polysulfone (PSF) substrate was tuned by blending with sulfonated poly (ether ether ketone) (SPEEK), and the resulting SPEEK blended PSF membrane was denoted as SPSF substrate. The pore structure of the SPSF membrane was tailored by the application of a co-casting technique, which yielded a TFC membrane with a structure parameter (S) of 191 μm. In contrast, the TFC membranes based on the PSF and SPSF substrates through single layer casting showed S values of 527 μm and 361 μm, respectively. These results indicate that the combined hydrophilicity and open pore structure are responsible for the lowered S value. Further application of the hydrophilic substrate based TFC membranes in the treatment of high salinity wastewaters (10 wt%) demonstrated the higher initial water flux (28.3 L/m 2 ·h) with a water recovery rate of 53.2% in comparison to the TFC membrane based on the pristine PSF through the single layer casting. This new method paves a way to generate high-performing FO membranes.
Kim, J, Blandin, G, Phuntsho, S, Verliefde, A, Le-Clech, P & Shon, H 2017, 'Practical considerations for operability of an 8″ spiral wound forward osmosis module: Hydrodynamics, fouling behaviour and cleaning strategy', Desalination, vol. 404, pp. 249-258.View/Download from: Publisher's site
A better understanding of large spiral wound forward osmosis (SW FO) module operation is needed to provide practical insight for a full-scale FO practical implementation desalination plant. Therefore, this study investigated two different 8″ SW FO modules (i.e. cellulose tri acetate, CTA and thin film composite, TFC) in terms of hydrodynamics, operating pressure, water and solute fluxes, fouling behaviour and cleaning strategy. For both modules, a significantly lower flow rate was required in the draw channel than in the feed channel due to important pressure-drop in the draw channel and was a particularly critical operating challenge in the CTA module when permeate spacers are used. Under FO and pressure assisted osmosis (PAO, up to 2.5ï¿½bar) operations, the TFC module featured higher water flux and lower reverse salt flux than the CTA module. For both modules, fouling tests demonstrated that feed inlet pressure was more sensitive to foulant deposition than the flux, thus confirming that FO fouling deposition occurs in the feed channel rather than on the membrane surface. Osmotic backwash combined with physical cleaning used in this study confirmed to be effective and adapted to large-scale FO module operation.
Kim, JE, Phuntsho, S, Chekli, L, Hong, S, Ghaffour, N, Leiknes, TO, Choi, JY & Shon, HK 2017, 'Environmental and economic impacts of fertilizer drawn forward osmosis and nanofiltration hybrid system', Desalination, vol. 416, pp. 76-85.View/Download from: Publisher's site
© 2017 Environmental and economic impacts of the fertilizer drawn forward osmosis (FDFO) and nanofiltration (NF) hybrid system were conducted and compared with conventional reverse osmosis (RO) hybrid scenarios using microfiltration (MF) or ultrafiltration (UF) as a pre-treatment process. The results showed that the FDFO-NF hybrid system using thin film composite forward osmosis (TFC) FO membrane has less environmental impact than conventional RO hybrid systems due to lower consumption of energy and cleaning chemicals. The energy requirement for the treatment of mine impaired water by the FDFO-NF hybrid system was 1.08 kWh/m 3 , which is 13.6% less energy than an MF-RO and 21% less than UF-RO under similar initial feed solution. In a closed-loop system, the FDFO-NF hybrid system using a TFC FO membrane with an optimum NF recovery rate of 84% had the lowest unit operating expenditure of AUD $0.41/m 3 . Besides, given the current relatively high price and low flux performance of the cellulose triacetate and TFC FO membranes, the FDFO-NF hybrid system still holds opportunities to reduce operating expenditure further. Optimizing NF recovery rates and improving the water flux of the membrane would decrease the unit OPEX costs, although the TFC FO membrane would be less sensitive to this effect.
Kim, Y, Li, S, Chekli, L, Phuntsho, S, Ghaffour, N, Leiknes, T & Shon, HK 2017, 'Influence of fertilizer draw solution properties on the process performance and microbial community structure in a side-stream anaerobic fertilizer-drawn forward osmosis - ultrafiltration bioreactor.', Bioresource Technology, vol. 240, pp. 149-156.View/Download from: Publisher's site
In this study, a side-stream anaerobic fertilizer-drawn forward osmosis (FDFO) and ultrafiltration (UF) membrane bioreactor (MBR) hybrid system was proposed and operated for 55days. The FDFO performance was first investigated in terms of flux decline with various fertilizers draw solution. Flux decline was very severe with all fertilizers due to the absence of aeration and the sticky property of sludge. Flux recovery by physical cleaning varied significantly amongst tested fertilizers which seriously affected biofouling in FDFO via reverse salt flux (RSF). Besides, RSF had a significant impact on nutrient accumulation in the bioreactor. These results indicated that nutrient accumulation negatively influenced the anaerobic activity. To elucidate these phenomena, bacterial and archaeal community structures were analyzed by pyrosequencing. Results showed that bacterial community structure was affected by fertilizer properties with less impact on archaeal community structure, which resulted in a reduction in biogas production and an increase in nitrogen content.
Kim, Y, Li, S, Chekli, L, Woo, YC, Wei, CH, Phuntsho, S, Ghaffour, N, Leiknes, TO & Shon, HK 2017, 'Assessing the removal of organic micro-pollutants from anaerobic membrane bioreactor effluent by fertilizer-drawn forward osmosis', Journal of Membrane Science, vol. 533, pp. 84-95.View/Download from: Publisher's site
© 2017 Elsevier B.V. In this study, the behavior of organic micro-pollutants (OMPs) transport including membrane fouling was assessed in fertilizer-drawn forward osmosis (FDFO) during treatment of the anaerobic membrane bioreactor (AnMBR) effluent. The flux decline was negligible when the FO membrane was oriented with active layer facing feed solution (AL-FS) while severe flux decline was observed with active layer facing draw solution (AL-DS) with di-ammonium phosphate (DAP) fertilizer as DS due to struvite scaling inside the membrane support layer. DAP DS however exhibited the lowest OMPs forward flux or higher OMPs rejection rate compared to other two fertilizers (i.e., mono-ammonium phosphate (MAP) and KCl). MAP and KCl fertilizer DS had higher water fluxes that induced higher external concentration polarization (ECP) and enhanced OMPs flux through the FO membrane. Under the AL-DS mode of membrane orientation, OMPs transport was further increased with MAP and KCl as DS due to enhanced concentrative internal concentration polarization while with DAP the internal scaling enhanced mass transfer resistance thereby lowering OMPs flux. Physical or hydraulic cleaning could successfully recover water flux for FO membranes operated under the AL-FS mode but only partial flux recovery was observed for membranes operated under AL-DS mode because of internal scaling and fouling in the support layer. Osmotic backwashing could however significantly improve the cleaning efficiency.
Kook, S, Kim, J, Kim, SJ, Lee, J, Han, D, Phuntsho, S, Shim, WG, Hwang, M, Shon, HK & Kim, IS 2017, 'Effect of initial feed and draw flowrates on performance of an 8040 spiral-wound forward osmosis membrane element', Desalination and Water Treatment, vol. 72, pp. 1-12.View/Download from: Publisher's site
© 2017, Desalination Publications. All rights reserved. This study investigated the effects of initial feed (20–50 L/min) and draw flowrates (2–5 L/min) on 8040 spiral-wound FO element performances in serial configuration for a forward osmosis and reverse osmosis (FO-RO) hybrid system employing single element-based tests. Average J w,ave values for varying feed and draw flowrates were found to be 20.93, 19.38 and 18.71 LMH at E1, E2 and E3 (first, second and third elements in a serial configuration), respectively, with averaged diluted draw concentrations of 12.55, 7.88 and 5.77 g/L (initial conc. = 35 g/L). The draw stream dilution was not governed by J w,ave but by the initial draw flowrates at the inlet that governs the retention time of the draw water body in the element. To sum up the performance results, it was concluded that initial draw flowrate is found to govern the performances of FO elements in series in terms of both production of diluted draw stream, determined by the averaged water flux of the FO element, J w,ave , and the degree of draw stream dilution. Specific energy consumptions (SECs) of RO were estimated with varying RO feed concentrations (i.e. diluted draw concentration); it was observed the efficiency of SEC reduction by the dilution significantly decays after a critical RO recovery rate. This study successfully provides a valuable insight for feasible application of the FO-RO hybrid system.
Lee, EJ, An, AK, Hadi, P, Lee, S, Woo, YC & Shon, HK 2017, 'Advanced multi-nozzle electrospun functionalized titanium dioxide/polyvinylidene fluoride-co-hexafluoropropylene (TiO2/PVDF-HFP) composite membranes for direct contact membrane distillation', Journal of Membrane Science, vol. 524, pp. 712-720.View/Download from: Publisher's site
The unique capabilities of electrospinning technology are being increasingly utilized in the fabrication of hydrophobic membranes to improve the membrane distillation (MD) process in recent years. In this study, hydrophobic titanium dioxide (TiO2) nanoparticles functionalized by fluorosilane were incorporated into electrospun membranes using single, coaxial, and dual nozzles to develop novel membrane architectures for improved physico-chemical properties for MD. By incorporating fluorosilane coated TiO2 into the PVDF-HFP solution during the membrane synthesis and using an advanced multi-nozzle to form various hierarchical membrane structures tuned the size and structure of the nanofibers and made them vastly superior for the application in MD. The single and coaxial nozzle membranes showed contact angles close to 150° and the dual-nozzle membrane assembled bead-on-string fibers achieved superhydrophobicity (i.e., contact angle of 153.4°). To test the functionalized titanium dioxide/polyvinylidene fluoride-co-hexafluoropropylene (TiO2/PVDF-HFP) composite membranes for MD performance, the membranes were subjected to long-term direct contact MD for about two days to monitor their water vapor flux and selectivity. Compared to commercial PVDF membranes, all electrospun F-TiO2/ PVDF-HFP membrane achieved higher water vapor flux of 40 L m−2 h−1 (60 °C feed and 20 °C permeate) with a brine (7.0 wt% NaCl) as the feed solution and also exhibited anti-wetting property while maintaining high water flux compared to the membrane without TiO2 incorporation.
Lee, E-J, Deka, BJ, Guo, J, Woo, YC, Shon, HK & An, AK 2017, 'Engineering the Re-Entrant Hierarchy and Surface Energy of PDMS-PVDF Membrane for Membrane Distillation Using a Facile and Benign Microsphere Coating.', Environmental Science and Technology, vol. 51, no. 17, pp. 10117-10126.View/Download from: Publisher's site
To consolidate the position of membrane distillation (MD) as an emerging membrane technology that meets global water challenges, it is crucial to develop membranes with ideal material properties. This study reports a facile approach for a polyvinylidene fluoride (PVDF) membrane surface modification that is achieved through the coating of the surface with poly(dimethylsiloxane) (PDMS) polymeric microspheres to lower the membrane surface energy. The hierarchical surface of the microspheres was built without any assistance of a nano/microcomposite by combining the rapid evaporation of tetrahydrofuran (THF) and the phase separation from condensed water vapor. The fabricated membrane exhibited superhydrophobicity-a high contact angle of 156.9° and a low contact-angle hysteresis of 11.3°-and a high wetting resistance to seawater containing sodium dodecyl sulfate (SDS). Compared with the control PVDF-hexafluoropropylene (HFP) single-layer nanofiber membrane, the proposed fabricated membrane with the polymeric microsphere layer showed a smaller pore size and higher liquid entry pressure (LEP). When it was tested for the direct-contact MD (DCMD) in terms of the desalination of seawater (3.5% of NaCl) containing SDS of a progressively increased concentration, the fabricated membrane showed stable desalination and partial wetting for the 0.1 and 0.2 mM SDS, respectively.
© 2017 Elsevier B.V. Ultrasound was used to improve a forward osmosis (FO) sludge dewatering process for the control of fouling by deposited sludge flocs. FO was able to concentrate activated sludge from a real-scale wastewater reclamation plant. However, the flux decline indicated a severe fouling phenomenon. To mitigate this FO fouling, ultrasound radiation using a novel cell configuration was applied. However, the application of continuous radiation unexpectedly resulted in more severe fouling. Fluorescence excitation-emission matrix (FEEM) spectroscopy showed that longer ultrasound radiation applications caused high organic release from sludge flocs. Confocal scanning laser microscopy (CLSM) clearly identified a thicker organic fouling layer on the FO membrane surface. Ultrasound cleaning was optimized for radiation length and improved by the integration of flushing. Specifically, the combination of ultrasound and flushing caused a flux loss recovery of 70% or more. This work demonstrated the possibility of ultrasound cleaning as a fouling control method for FO sludge dewatering applications.
Li, S, Kim, Y, Chekli, L, Phuntsho, S, Shon, HK, Leiknes, TO & Ghaffour, N 2017, 'Impact of reverse nutrient diffusion on membrane biofouling in fertilizer-drawn forward osmosis', Journal of Membrane Science, vol. 539, pp. 108-115.View/Download from: Publisher's site
© 2017 Elsevier B.V. Biofouling in fertilizer-drawn forward osmosis (FDFO) for water reuse was investigated by spiking pure bacteria species Pseudomonas aeruginosa PAO1+GFP and using three different fertilizers KNO 3 , KCl and KH 2 PO 4 as draw solutions. The performance of FO process for treating synthetic wastewater was assessed and their influence on the membrane fouling and in particular biofouling was evaluated relative to the type of different fertilizers used and their rates of reverse diffusion. FO performances using KNO 3 as draw solute exhibited severer flux decline (63%) than when using KCl (45%) and KH 2 PO 4 (30%). Membrane autopsy indicated that the mass of organic foulants and biomass on fouled membrane surface using KNO 3 as draw solute (947.5 mg/m 2 biopolymers, 72 µm biofilm thickness and 53.3 mg/m 2 adenosine triphosphate) were significantly higher than that using KCl (450 mg/m 2 biopolymers, 33 µm biofilm thickness and 28.2 mg/m 2 ATP) and KH 2 PO 4 (440 mg/m 2 biopolymers, 35 µm biofilm thickness and 33.5 mg/m 2 ATP). This higher flux decline is likely related to the higher reverse diffusion of KNO 3 (19.8 g/m 2 /h) than KCl (5.1 g/m 2 /h) and KH 2 PO 4 (3.7 g/m 2 /h). The reverse diffused potassium could promote the organics and bacterial adhesion on FO membrane via charge screening effect and compression of electrical double layer. Moreover, reverse diffused nitrate provided increased N:P nutrient ratio was favorable for the bacteria to grow on the feed side of the FO membrane.
Li, S, Kim, Y, Phuntsho, S, Chekli, L, Shon, HK, Leiknes, T & Ghaffour, N 2017, 'Methane production in an anaerobic osmotic membrane bioreactor using forward osmosis: Effect of reverse salt flux.', Bioresource Technology, vol. 239, pp. 285-293.View/Download from: Publisher's site
This study investigated the impact of reverse salt flux (RSF) on microbe community and bio-methane production in a simulated fertilizer driven FO-AnMBR system using KCl, KNO3 and KH2PO4 as draw solutes. Results showed that KH2PO4 exhibited the lowest RSF in terms of molar concentration 19.1mM/(m2.h), while for KCl and KNO3 it was 32.2 and 120.8mM/(m2.h), respectively. Interestingly, bio-methane production displayed an opposite order with KH2PO4, followed by KCl and KNO3. Pyrosequencing results revealed the presence of different bacterial communities among the tested fertilizers. Bacterial community of sludge exposed to KH2PO4 was very similar to that of DI-water and KCl. However, results with KNO3 were different since the denitrifying bacteria were found to have a higher percentage than the sludge with other fertilizers. This study demonstrated that RSF has a negative effect on bio-methane production, probably by influencing the sludge bacterial community via environment modification.
Lotfi, F, Chekli, L, Phuntsho, S, Hong, S, Choi, JY & Shon, HK 2017, 'Understanding the possible underlying mechanisms for low fouling tendency of the forward osmosis and pressure assisted osmosis processes', Desalination, vol. 421, pp. 89-98.View/Download from: Publisher's site
© 2017 Elsevier B.V. We investigated the possible underlying mechanism of the low fouling potential in the forward osmosis (FO) process during the osmotic dilution of seawater as part of the simultaneous desalination and wastewater reuse by FO and reverse osmosis hybrid system. Long-term experiments revealed an interesting water flux pattern highly dependent on the different operating parameters. The most interesting observation made was the spontaneous increase in the FO permeate flux at regular time interval during the FO operation using synthetic wastewater as feed and seawater. This sinusoidal FO flux pattern related well with the build-up of loose fouling layer and their natural peel-off from the membrane surface upon reaching certain layer thickness due to crossflow velocity shear. This flux pattern was more prominent at higher cross-flow velocity rates, lower feed water pH, for a smoother membrane surface and at lower operating pressure during pressure assisted osmosis (PAO) mode. Based on these results, membrane cleaning strategies were proposed by targeting a higher cross-flow velocity shear at a time when the permeate flux started to just increase. The approach of physical membrane cleaning was observed efficient and was able to almost fully restore the initial flux even under the PAO operation at 4 bar.
Phuntsho, S, Kim, JE, Hong, S, Ghaffour, N, Leiknes, TO, Choi, JY & Shon, HK 2017, 'A closed-loop forward osmosis-nanofiltration hybrid system: Understanding process implications through full-scale simulation', Desalination, vol. 421, pp. 169-178.View/Download from: Publisher's site
© 2016 Elsevier B.V.This study presents simulation of a closed-loop forward osmosis (FO)-nanofiltration (NF) hybrid system using fertiliser draw solution (DS) based on thermodynamic mass balance in a full-scale system neglecting the non-idealities such as finite membrane area that may exist in a real process. The simulation shows that the DS input parameters such as initial concentrations and its flow rates cannot be arbitrarily selected for a plant with defined volume output. For a fixed FO-NF plant capacity and feed concentration, the required initial DS flow rate varies inversely with the initial DS concentration or vice-versa. The net DS mass flow rate, a parameter constant for a fixed plant capacity but that increases linearly with the plant capacity and feed concentration, is the most important operational parameter of a closed-loop system. Increasing either of them or both increases the mass flow rate to the system directly affecting the final concentration of the diluted DS with direct energy implications to the NF process. Besides, the initial DS concentration and flow rates are also limited by the optimum recovery rates at which NF process can be operated which otherwise also have direct implications to the NF energy. This simulation also presents quantitative analysis of the reverse diffusion of fertiliser nutrients towards feed brine and the gradual accumulation of feed solutes within the closed system.
Shon, HK, Jegatheesan, V, Shu, L & Phuntsho, S 2017, 'Challenges in Environmental Science and Engineering, CESE–2016', Process Safety and Environmental Protection, vol. 112, no. PART B, pp. 199-199.View/Download from: Publisher's site
Tran, VH, Phuntsho, S, Park, H, Han, DS & Shon, HK 2017, 'Sulfur-containing air pollutants as draw solution for fertilizer drawn forward osmosis desalination process for irrigation use', Desalination, vol. 424, pp. 1-9.View/Download from: Publisher's site
© 2017 Elsevier B.V. This study investigated suitability and performance of the sulfur-based seed solution (SBSS) as a draw solution (DS), a byproduct taken from the photoelectrochemical (PEC) process where the SBSS is used as an electrolyte for H 2 production. This SBSS DS is composed of a mixture of ammonium sulfate ((NH 4 ) 2 SO 4 ) and ammonium sulfite ((NH 4 ) 2 SO 3 ), and it can be utilized as fertilizer for fertilizer drawn forward osmosis (FDFO) desalination of saline water. The FDFO process employed with thin-film composite (TFC) membrane and showed that the process performance (i.e. water flux and reverse salt flux) is better than that with cellulose triacetate (CTA) membrane. In addition, it produced high water flux of 19 LMH using SBSS as DS at equivalent concentration at 1 M and 5 g/L NaCl of feed solution (model saline water). Experimental results showed that the reverse salt flux of SBSS increased with the increase in pH of the DS and that lowering the concentration of ammonium sulfite in the SBSS led to the higher water flux of feed solution. The result also demonstrated that this SBSS is practically suitable for the FDFO process toward development of water-energy-food nexus technology using sulfur chemicals-containing air pollutant.
Wang, C, Gao, B, Zhao, P, Li, R, Yue, Q & Shon, HK 2017, 'Exploration of polyepoxysuccinic acid as a novel draw solution in the forward osmosis process', RSC Advances, vol. 7, no. 49, pp. 30687-30698.View/Download from: Publisher's site
© 2017 The Royal Society of Chemistry. Polyepoxysuccinic acid (PESA) is a green corrosion scale inhibitor. When PESA is used for wastewater desalination in the forward osmosis (FO) process, the diluted PESA solution could be used for cooling systems. In our investigation, the effects of membrane orientation, temperature and flow rate on FO performance are studied using PESA as a draw solute. The results show that the effect of temperature on water flux is obvious, but the water flux increase is higher from 25 °C to 35 °C than that from 35 °C to 45 °C. Compared to the FO mode, the water flux increases faster in the pressure-retarded osmosis mode (PRO mode) at high flow rate due to the reduction of concentrative internal concentration polarization (CICP). Compared with polyaspartic acid (PASP) and NaCl, the water flux of PESA is the lowest under the same conditions. However, PESA has the lowest specific reverse solute flux (J s /J w ) at both membrane orientations. For example in the FO mode this value is 0.46 g L -1 , whereas that of NaCl and PASP is 1.12 and 0.74 g L -1 , respectively. This means that PESA has lower loss to the feed side than NaCl and PASP in the FO process, which greatly reduces the replenishment cost of the draw solute. The use of PESA as the draw solute in the FO process to treat dyeing water has the advantages of stable water flux (within 20 min), high dye rejection (nearly 1) and reversible membrane fouling (restored to 97%). The nanofiltration (NF) process indicates the good performance of PESA recovery with a high specific water flux (0.94 LMH per bar) and rejection rate (97.8%). Thus, the overall performance of PESA demonstrates that it is a promising draw solute.
Zhao, Y, Phuntsho, S, Gao, B & Shon, H 2017, 'Polytitanium sulfate (PTS): Coagulation application and Ti species detection', Journal of Environmental Sciences, vol. 52, pp. 250-258.View/Download from: Publisher's site
© 2016.Interest in the development of inorganic polymerized coagulants is growing; however, there are only limited studies on the synthesis of polytitanium coagulants, which are expected to exhibit improved coagulation efficiency with better floc properties. This study presents the synthesis of polytitanium sulfate (PTS) for potential application in water purification, followed by characterization of PTS flocs and titanium species detection. Stable PTS solutions were successfully synthesized and standard jar tests were conducted to evaluate their coagulation efficiency. Electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) speciation analysis revealed that a variety of mononuclear and polynuclear complexes were formed in PTS solution, indicating the polymeric nature of the synthesized coagulant. Floc characteristics were studied through on-line monitoring of floc size using a laser diffraction particle size analyzer. Results showed that PTS had a comparable or in some cases even higher organic matter and particulate removal efficiency than Ti(SO4)2. The effluent pH after PTS coagulation significantly improved toward desirable values closer to neutral pH. Properties of flocs formed by PTS were significantly improved in terms of floc size, growth rate and structure. This study showed that PTS could be an efficient and promising coagulant for water purification, with the additional benefit that its coagulated sludge can be used to recover valuable TiO2 nanoparticles for various commercial applications.
Zhao, Y, Sun, Y, Tian, C, Gao, B, Wang, Y, Shon, H & Yang, Y 2017, 'Titanium tetrachloride for silver nanoparticle-humic acid composite contaminant removal in coagulation-ultrafiltration hybrid process: floc property and membrane fouling.', Environmental Science and Pollution Research, vol. 24, no. 2, pp. 1757-1768.View/Download from: Publisher's site
Titanium-based coagulation is expected to achieve both efficient water purification and sludge recycling. This study is the first attempt to use titanium tetrachloride (TiCl4) for silver nanoparticle (AgNP)-humic acid composite contaminant removal in a coagulation-ultrafiltration (C-UF) process, where characterization of flocs and membrane fouling under varied coagulant dose, initial solution pH, and AgNP concentration conditions are the main contents. Results suggested that the TiCl4 achieved high AgNP removal in the form of silver nanoparticle through adsorption and sweep flocculation and simultaneously exerted additional 68.2 % higher dissolved organic carbon removal than Al2(SO4)3. The TiCl4 produced larger and stronger flocs but with weaker recoverability and less compact degree than did Al2(SO4)3. Floc properties were independent of AgNP concentration except floc fractal dimension, which was negatively correlated with AgNP concentration. The TiCl4 precoagulation caused less membrane fouling within wider pH range than Al2(SO4)3 did in the C-UF process. Incorporation of AgNPs during the TiCl4 pretreatment process facilitated the mitigation of membrane fouling, which was, however, negligibly influenced by AgNP concentration in the case of Al2(SO4)3.
Pathak, N, Chekli, L, Wang, J, Kim, Y, Phuntsho, S, Li, S, Ghaffour, N, Leiknes, T & Shon, H 2017, 'Performance of a novel baffled osmotic membrane bioreactor-microfiltration hybrid system under continuous operation for simultaneous nutrient removal and mitigation of brine discharge.', Bioresource Technology, vol. 240, pp. 50-58.View/Download from: Publisher's site
The present study investigated the performance of an integrated osmotic and microfiltration membrane bioreactor system for wastewater treatment employing baffles in the reactor. Thus, this reactor design enables both aerobic and anoxic processes in an attempt to reduce the process footprint and energy costs associated with continuous aeration. The process performance was evaluated in terms of water flux, salinity build up in the bioreactor, organic and nutrient removal and microbial activity using synthetic reverse osmosis (RO) brine as draw solution (DS). The incorporation of MF membrane was effective in maintaining a reasonable salinity level (612-1434mg/L) in the reactor which resulted in a much lower flux decline (i.e. 11.48-6.98LMH) as compared to previous studies. The stable operation of the osmotic membrane bioreactor-forward osmosis (OMBR-FO) process resulted in an effective removal of both organic matter (97.84%) and nutrient (phosphate 87.36% and total nitrogen 94.28%), respectively.
Wang, J, Pathak, N, Chekli, L, Phuntsho, S, Kim, Y, Li, D & Shon, HK 2017, 'Performance of a novel fertilizer-drawn forward osmosis aerobic membrane bioreactor (FDFO-MBR): Mitigating salinity build-up by integrating microfiltration', Water, vol. 9, no. 1, pp. 1-13.View/Download from: Publisher's site
© 2017 by the authors. In this paper, three different fertilizer draw solutions were tested in a novel forward osmosis-microfiltration aerobic membrane bioreactor (MF-FDFO-MBR) hybrid system and their performance were evaluated in terms of water flux and reverse salt diffusion. Results were also compared with a standard solution. Results showed that ammonium sulfate is the most suitable fertilizer for this hybrid system since it has a relatively high water flux (6.85 LMH) with a comparatively low reverse salt flux (3.02 gMH). The performance of the process was also studied by investigating different process parameters: draw solution concentration, FO draw solution flow rate and MF imposed flux. It was found that the optimal conditions for this hybrid system were: draw solution concentration of 1 M, FO draw solution flow rate of 200 mL/min and MF imposed flux of 10 LMH. The salt accumulation increased from 834 to 5400 μS/cm during the first four weeks but after integrating MF, the salinity dropped significantly from 5400 to 1100 μS/cm suggesting that MF is efficient in mitigating the salinity build up inside the reactor. This study demonstrated that the integration of the MF membrane could effectively control the salinity and enhance the stable FO flux in the OMBR.
Kim, Y, Woo, YC, Phuntsho, S, Nghiem, LD, Shon, HK & Hong, S 2017, 'Evaluation of fertilizer-drawn forward osmosis for coal seam gas reverse osmosis brine treatment and sustainable agricultural reuse', Journal of Membrane Science, vol. 537, pp. 22-31.View/Download from: Publisher's site
© 2017 Elsevier B.V. The fertilizer-drawn forward osmosis (FDFO) was investigated for treating coal seam gas (CSG) produced water to generate nutrient rich solution for irrigation. Its performance was evaluated and compared with reverse osmosis (RO) in terms of specific energy consumption (SEC) and nutrient concentrations in the final product water. The RO-FDFO hybrid process was developed to further improve FDFO. The results showed that FDFO has the lowest SEC followed by the RO-FDFO and RO processes. The final nutrient concentration simulation demonstrated that the RO-FDFO hybrid process has lower final concentration, higher maximum recovery and lower nutrient loss th an the stand alone FDFO process. Therefore, it was suggested that the RO-FDFO is the most effective treatment option for CSG produced water as well as favourable nutrient supply. Lastly, membrane fouling mechanism was examined in CSG RO brine treatment by FDFO, and the strategies for controlling fouling were critically evaluated. KNO 3 exhibited the highest flux decline corresponding to the highest reverse salt flux, while the most severe membrane scaling was observed with calcium nitrate, primarily due to the reverse transport of calcium ions. To control membrane fouling in FDFO process, both physical flushing and chemical cleaning were examined. Membrane cleaning with citric acid of 5% resulted in a complete flux recovery.
Shon, HK, Nghiem, LD, Kim, S, Chiemchaisri, C, Tijing, L, Shu, L & Jegatheesan, V 2017, 'Special issue on the 9th International Conference onChallenges in Environmental Science and Engineering (CESE-2016)6–10 November 2016, Kaohsiung, Taiwan', Desalination and Water Treatment, vol. 96, pp. 1-2.View/Download from: Publisher's site
Sahebi, S, Phuntsho, S, Woo, YC, Park, MJ, Tijing, LD, Hong, S & Shon, HK 2016, 'Effect of sulphonated polyethersulfone substrate for thin film composite forward osmosis membrane', DESALINATION, vol. 389, pp. 129-136.View/Download from: Publisher's site
Sianipar, M, Kim, SH, Min, C, Tijing, LD & Shon, HK 2016, 'Potential and performance of a polydopamine-coated multiwalled carbon nanotube/polysulfone nanocomposite membrane for ultrafiltration application', JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY, vol. 34, pp. 364-373.View/Download from: Publisher's site
Tijing, LD, Woo, YC, Shim, W-G, He, T, Choi, J-S, Kim, S-H & Shon, HK 2016, 'Superhydrophobic nanofiber membrane containing carbon nanotubes for high-performance direct contact membrane distillation', JOURNAL OF MEMBRANE SCIENCE, vol. 502, pp. 158-170.View/Download from: Publisher's site
Woo, YC, Lee, JJ, Shim, W-G, Shon, HK, Tijing, LD, Yao, M & Kim, H-S 2016, 'Effect of powdered activated carbon on integrated submerged membrane bioreactor-nanofiltration process for wastewater reclamation', BIORESOURCE TECHNOLOGY, vol. 210, pp. 18-25.View/Download from: Publisher's site
Woo, YC, Tijing, LD, Shim, W-G, Choi, J-S, Kim, S-H, He, T, Drioli, E & Shon, HK 2016, 'Water desalination using graphene-enhanced electrospun nanofiber membrane via air gap membrane distillation', JOURNAL OF MEMBRANE SCIENCE, vol. 520, pp. 99-110.View/Download from: Publisher's site
Water desalination using graphene-enhanced electrospun nanofiber membrane via air gap membrane distillation
Yao, M, Woo, YC, Tijing, L, Shim, WG, Choi, JS, Kim, SH & Shon, HK 2016, 'Effect of heat-press conditions on electrospun membranes for desalination by direct contact membrane distillation', Desalination, vol. 378, pp. 80-91.View/Download from: Publisher's site
Membrane distillation (MD) is considered as a promising next-generation technology for desalination. However, there is no specific membrane designed and engineered for this application yet. Recently, electrospun polymeric membranes have been widely investigated due to their relatively high porosity, high hydrophobicity and controllable pore size. However, the robustness of such membranes is not guaranteed as they are susceptible to wetting in long-term operation. Heat-press treatment is a simple and effective procedure to improve both morphological and mechanical characteristics of the electrospun membrane. Nevertheless, the heat-press technique is not fully investigated although some conditions are applied to the electrospun membrane in previous researches. In this paper, a comprehensive investigation of the effect of heat-press temperature, pressure and duration on the morphological and mechanical characteristics of electrospun membrane is accomplished. Impressive improvement of mechanical strength and liquid entry pressure (LEP) can be achieved after heat-press treatment on the electrospun membranes. It is also found that temperature and duration play more important roles than pressure in heat-press treatment. In addition, it is ascertained that optimal treatment conditions for heat-press includes temperature at 150 °C, pressure at 6.5 kPa, and duration for 8 h for the present electrospun polyvinylidene fluoride-co-hexafluoropropylene membrane. A decent DCMD permeation flux of 29 LMH and salt rejection of 99.99% can be achieved with the optimally heat-pressed electrospun membranes for desalination at feed and permeate temperatures of 60 and 20 °C, respectively.
© 2016 Elsevier B.V. In this study, colloidal fouling behavior in pressure retarded osmosis (PRO) was systematically investigated in terms of the effects of draw solution concentration, applied hydraulic pressure at the draw side, feed solution pH, and particle size. Commercially-available cellulose triacetate (CTA) membranes were fouled with feed solution containing silica colloidal particles. Two different silica particles with mean diameter of 27 and 152. nm were used as model foulants. Our findings demonstrated that the colloidal fouling in PRO was dominantly affected by the cake layer buildup at the membrane surface. Fouling was further exacerbated by diffused salts from the draw side because retained salts within the cake layer elevated the salt concentration on the membrane surface, and consequently reduced the driving force of PRO. Substantial flux decline with the smaller particles was attributed to the high cake layer resistance due to the formation of the void-less cake layer. In addition, our approaches to mitigate the colloidal fouling revealed that the hydraulic cleaning by increasing the cross-flow rates was not effective to eliminate the compact cake layer. However, adjusting the feed solution pH showed the high potential to relieve the colloidal fouling resulting from the more stabilization of particles at low solution pH.
Park, MJ, Nisola, GM, Vivas, EL, Limjuco, LA, Lawagon, CP, Seo, JG, Kim, H, Shon, HK & Chung, W-J 2016, 'Mixed matrix nanofiber as a flow-through membrane adsorber for continuous Li+ recovery from seawater', JOURNAL OF MEMBRANE SCIENCE, vol. 510, pp. 141-154.View/Download from: Publisher's site
Zhang, M, Liu, R, Wang, Z, Zhao, B, Song, J, Park, MJ, Shon, HK, Li, X-M & He, T 2016, 'Dehydration of forward osmosis membranes in treating high salinity wastewaters: Performance and implications', JOURNAL OF MEMBRANE SCIENCE, vol. 498, pp. 365-373.View/Download from: Publisher's site
Chekli, L, Bayatsarmadi, B, Sekine, R, Sarkar, B, Shen, AM, Scheckel, KG, Skinner, W, Naidu, R, Shon, HK, Lombi, E & Donner, E 2016, 'Analytical characterisation of nanoscale zero-valent iron: A methodological review', ANALYTICA CHIMICA ACTA, vol. 903, pp. 13-35.View/Download from: Publisher's site
Chekli, L, Brunetti, G, Marzouk, ER, Maoz-Shen, A, Smith, E, Naidu, R, Shon, HK, Lombi, E & Donner, E 2016, 'Evaluating the mobility of polymer-stabilised zero-valent iron nanoparticles and their potential to co-transport contaminants in intact soil cores', ENVIRONMENTAL POLLUTION, vol. 216, pp. 636-645.View/Download from: Publisher's site
Chekli, LM, Phuntsho, S, Kim, JE, Kim, JH, Choi, JY, Choi, JS, Kim, SH, Kim, JH, Hong, SK, Sohn, JS & Shon, HK 2016, 'A comprehensive review of hybrid forward osmosis systems: Performance, applications and future prospects', Journal of Membrane Science, vol. 497, no. 1, pp. 430-449.View/Download from: Publisher's site
Forward osmosis (FO) has been increasingly studied in the past decade for its potential as an emerging low-energy water and wastewater treatment process. However, the term “low-energy” may only be suitable for those applications in where no further treatment of the draw solution (DS) is required either in the form of pretreatment or post-treatment to the FO process (e.g. where the diluted DS is the targeted final product which can be used directly or simply discarded). In most applications, FO has to be coupled with another separation process in a so-called hybrid FO system to either separate the DS from the final product water or to be used as an advanced pre-treatment process to conventional desalination technologies. The additional process increases the capital cost as well as the energy demand of the overall system which is one of the several challenges that hybrid FO systems need to overcome to compete with other separation technologies. Yet, there are some applications where hybrid FO systems can outperform conventional processes and this study aims to provide a comprehensive review on the current state of hybrid FO systems. The recent development and performance of hybrid FO systems in different applications have been reported. This review also highlights the future research directions for the current hybrid FO systems to achieve successful implementation.
Chen, G, Wang, Z, Li, X-M, Song, J, Zhao, B, Phuntsho, S, Shon, HK & He, T 2016, 'Concentrating underground brine by FO process: Influence of membrane types and spacer on membrane scaling', CHEMICAL ENGINEERING JOURNAL, vol. 285, pp. 92-100.View/Download from: Publisher's site
Kim, J, Park, M, Shon, HK & Kim, JH 2016, 'Performance analysis of reverse osmosis, membrane distillation, and pressure-retarded osmosis hybrid processes', DESALINATION, vol. 380, pp. 85-92.View/Download from: Publisher's site
Kim, Y, Chekli, L, Shim, W-G, Phuntsho, S, Li, S, Ghaffour, N, Leiknes, T & Shon, HK 2016, 'Selection of suitable fertilizer draw solute for a novel fertilizer-drawn forward osmosis-anaerobic membrane bioreactor hybrid system', BIORESOURCE TECHNOLOGY, vol. 210, pp. 26-34.View/Download from: Publisher's site
Lee, E-J, An, AK, He, T, Woo, YC & Shon, HK 2016, 'Electrospun nanofiber membranes incorporating fluorosilane-coated TiO2 nanocomposite for direct contact membrane distillation', JOURNAL OF MEMBRANE SCIENCE, vol. 520, pp. 145-154.View/Download from: Publisher's site
Lee, KY, Park, SM, Kim, JB, El Saliby, I, Shahid, M, Kim, G-J, Shon, HK & Kim, J-H 2016, 'Synthesis and Characterisation of Porous Titania-Silica Composite Aerogel for NOx and Acetaldehyde Removal', JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, vol. 16, no. 5, pp. 4505-4511.View/Download from: Publisher's site
Majeed, T, Phuntsho, S, Chekli, L, Lee, S-H, Kim, K & Shon, HK 2016, 'Role of various physical and chemical techniques for hollow fibre forward osmosis membrane cleaning', DESALINATION AND WATER TREATMENT, vol. 57, no. 17, pp. 7742-7752.View/Download from: Publisher's site
Majeed, T, Phuntsho, S, Jeong, S, Zhao, Y, Gao, B & Shon, HK 2016, 'Understanding the risk of scaling and fouling in hollow fiber forward osmosis membrane application', PROCESS SAFETY AND ENVIRONMENTAL PROTECTION, vol. 103, pp. 452-464.View/Download from: Publisher's site
Majeed, T, Phuntsho, S, Jeong, S, Zhao, Y, Gao, B & Shon, HK 2016, 'Understanding the risk of scaling and fouling in hollow fiber forward osmosis membrane application', PROCESS SAFETY AND ENVIRONMENTAL PROTECTION, vol. 104, pp. 452-464.View/Download from: Publisher's site
Phuntsho, S, Kim, JE, Johir, MAH, Hong, S, Li, Z, Ghaffour, N, Leiknes, T & Shon, HK 2016, 'Fertiliser drawn forward osmosis process: Pilot-scale desalination of mine impaired water for fertigation', JOURNAL OF MEMBRANE SCIENCE, vol. 508, pp. 22-31.View/Download from: Publisher's site
Shon, HK, Phuntsho, S & Jegatheesan, V 2016, 'Special Issue - Challenges in Environmental Science and Engineering', PROCESS SAFETY AND ENVIRONMENTAL PROTECTION, vol. 104, pp. 451-451.View/Download from: Publisher's site
Xie, M, Shon, HK, Gray, SR & Elimelech, M 2016, 'Membrane-based processes for wastewater nutrient recovery: Technology, challenges, and future direction', WATER RESEARCH, vol. 89, pp. 210-221.View/Download from: Publisher's site
Zhao, P, Gao, B, Yue, Q, Liu, P & Shon, HK 2016, 'Fatty acid fouling of forward osmosis membrane: Effects of pH, calcium, membrane orientation, initial permeate flux and foulant composition', Journal of Environmental Sciences (China), vol. 46, pp. 55-62.View/Download from: Publisher's site
Octanoic acid (OA) was selected to represent fatty acids in effluent organic matter (EOM). The effects of feed solution (FS) properties, membrane orientation and initial permeate flux on OA fouling in forward osmosis (FO) were investigated. The undissociated OA formed a cake layer quickly and caused the water flux to decline significantly in the initial 0.5hr at unadjusted pH3.56; while the fully dissociated OA behaved as an anionic surfactant and promoted the water permeation at an elevated pH of 9.00. Moreover, except at the initial stage, the sudden decline of water flux (meaning the occurrence of severe membrane fouling) occurred in two conditions: 1. 0.5mmol/L Ca2+, active layer facing draw solution (AL-DS) and 1.5mol/L NaCl (DS); 2. No Ca2+, active layer-facing FS (AL-FS) and 4mol/L NaCl (DS). This demonstrated that cake layer compaction or pore blocking occurred only when enough foulants were absorbed into the membrane surface, and the water permeation was high enough to compact the deposit inside the porous substrate. Furthermore, bovine serum albumin (BSA) was selected as a co-foulant. The water flux of both co-foulants was between the fluxes obtained separately for the two foulants at pH3.56, and larger than the two values at pH9.00. This manifested that, at pH3.56, BSA alleviated the effect of the cake layer caused by OA, and OA enhanced BSA fouling simultaneously; while at pH9.00, the mutual effects of OA and BSA eased the membrane fouling.
Zhao, P, Gao, B, Yue, Q, Liu, S & Shon, HK 2016, 'Effect of high salinity on the performance of forward osmosis: Water flux, membrane scaling and removal efficiency', DESALINATION, vol. 378, pp. 67-73.View/Download from: Publisher's site
Zhao, P, Gao, B, Yue, Q, Liu, S & Shon, HK 2016, 'The performance of forward osmosis in treating high-salinity wastewater containing heavy metal Ni2+', CHEMICAL ENGINEERING JOURNAL, vol. 288, pp. 569-576.View/Download from: Publisher's site
Zhao, P, Gao, B, Yue, Q, Shon, HK & Li, Q 2016, 'Fouling of forward osmosis membrane by protein (BSA): effects of pH, calcium, ionic strength, initial permeate flux, membrane orientation and foulant composition', Desalination and Water Treatment, vol. 57, no. 29, pp. 13415-13424.View/Download from: Publisher's site
© 2015 Balaban Desalination Publications. All rights reserved. In this study, bovine serum albumin (BSA) was selected to represent proteins of secondary wastewater effluent. The role of various physical and chemical interactions, such as calcium concentration, ionic strength, solution pH, feed foulant composition, initial permeate flux, and membrane orientation, in BSA fouling of forward osmosis (FO) membranes was investigated. Fouling experiments showed that membrane fouling by BSA was enhanced with increasing calcium concentration and ionic strength. The former was mainly due to the complexes formed by the interaction of Ca2+ and carboxylic functional groups of BSA, and the latter resulted from the decreasing electrostatic repulsion among BSA molecules and between BSA molecules and membrane. Moreover, FO membrane fouling became much more significant at solution pH 4.7 (the BSA isoelectric point), where BSA molecules were neutrally charged and had no electrostatic repulsion among themselves. It was also demonstrated that the presence of alginate (a model polysaccharide) as co-foulant aggravated the BSA fouling of FO membrane, which could be attributed to the remarkable contribution of the alginateBSACa2+ complexes within the fouling layer to the total membrane resistance. The fouled membranes were examined by scanning electron microscopy to further sustain the conclusion. In addition, the size distribution of foulant molecules in various FS was measured and used as a reference to judge and control the behavior of BSA fouling. The present paper is contributed to better understanding of FO membrane fouling caused by protein (BSA) and has instructive significance for the future development.
Shon, HK, Nghiem, LD, Kim, S, Zakaria, ZA, Tijing, L, Shu, L & Jegatheesan, V 2016, 'Selected papers presented at The 2nd IWA Malaysia Young Water Professionals Conference 2015 (YWP15) - Aspiring Beyond Water Solution March 17-20, 2015, Langkawi Island, Malaysia', DESALINATION AND WATER TREATMENT, vol. 57, no. 60, pp. 29192-29192.View/Download from: Publisher's site
Woo, YC, Kim, Y, Shim, W-G, Tijing, LD, Yao, M, Nghiem, LD, Choi, J-S, Kim, S-H & Shon, HK 2016, 'Graphene/PVDF flat-sheet membrane for the treatment of RO brine from coal seam gas produced water by air gap membrane distillation', JOURNAL OF MEMBRANE SCIENCE, vol. 513, pp. 74-84.View/Download from: Publisher's site
Shahid, M, El Saliby, I, McDonagh, A, Chekli, L, Tijing, L, Kim, JH & Shon, H 2016, 'Adsorption and Photocatalytic Degradation of Methylene Blue Using Potassium Polytitanate and Solar Simulator', Journal of Nanoscience and Nanotechnology, vol. 16, pp. 4342-4349.View/Download from: Publisher's site
Solar photocatalytic degradation of organic water pollutants can be used to degrade toxic organic
pollutants in water. In this study, potassium titanate nanofibres were synthesized by an aqueous
peroxide route at high pH and examined as photocatalysts for photodegradation of methylene
blue (MB) using a solar simulator. Initially, MB was adsorbed on the surface of potassium polytitanates
to achieve adsorption equilibrium before the photocatalysts were illuminated using solar
simulator. The results showed that potassium polytitanate nanofibres were effective adsorbents of
MB and also facilitated its photocatalytic degradation. Sulphate ion evolution during photocatalysis
confirmed that some mineralisation occurred and hence photo-oxidative degradation of MB took
place. The optimum operational conditions for the photocatalytic degradation of MB were found
at 0.05 g/L of photocatalyst load, 10 mg/L MB and pH 7. The stability and regeneration of the
photocatalyst specimen was also studied for 3 degradation cycles using adsorption/photocatalysis
model. Morphological structure analysis of potassium titanate showed nanocrystallines structure of
longitudinally-oriented isolated fibre with a length up to several micrometres with diameters ranging
from 10 to 20 nanometres.
Shahid, M, Tijing, LD, El Saliby, I, McDonagh, A, Kim, J-B, Kim, J-H & Shon, HK 2016, 'Adsorption Behavior of Pb(II) Onto Potassium Polytitanate Nanofibres', JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, vol. 16, no. 2, pp. 1916-1919.View/Download from: Publisher's site
Chekli, L, Roy, M, Tijing, LD, Donner, E, Lombi, E & Shon, HK 2015, 'Agglomeration behaviour of titanium dioxide nanoparticles in river waters: A multi-method approach combining light scattering and field-flow fractionation techniques', JOURNAL OF ENVIRONMENTAL MANAGEMENT, vol. 159, pp. 135-142.View/Download from: Publisher's site
Chekli, L, Zhao, YX, Tijing, LD, Phuntsho, S, Donner, E, Lombi, E, Gao, BY & Shon, HK 2015, 'Aggregation behaviour of engineered nanoparticles in natural waters: Characterising aggregate structure using on-line laser light scattering', Journal of hazardous materials, vol. 284, pp. 190-200.View/Download from: Publisher's site
Galloux, J, Chekli, L, Phuntsho, S, Tijing, LD, Jeong, S, Zhao, YX, Gao, BY, Park, SH & Shon, HK 2015, 'Coagulation performance and floc characteristics of polytitanium tetrachloride and titanium tetrachloride compared with ferric chloride for coal mining wastewater treatment', SEPARATION AND PURIFICATION TECHNOLOGY, vol. 152, pp. 94-100.View/Download from: Publisher's site
Jiang, Z, Tijing, LD, Amarjargal, A, Park, CH, An, K-J, Shon, HK & Kim, CS 2015, 'Removal of oil from water using magnetic bicomponent composite nanofibers fabricated by electrospinning', COMPOSITES PART B-ENGINEERING, vol. 77, pp. 311-318.View/Download from: Publisher's site
Majeed, T, Sahebi, S, Lotfi, F, Kim, JE, Phuntsho, S, Tijing, LD & Shon, HK 2015, 'Fertilizer-drawn forward osmosis for irrigation of tomatoes', Desalination and Water Treatment, vol. 53, no. 10, pp. 2746-2759.View/Download from: Publisher's site
Park, MJ, Phuntsho, S, He, T, Grace, MN, Tijing, LD, Li, XM, Chen, G, Chung, WJ & Shon, HK 2015, 'Graphene oxide incorporated polysulfone substrate for the fabrication of flat-sheet thin-film composite forward osmosis membranes', Journal of Membrane Science, vol. 493, pp. 496-507.View/Download from: Publisher's site
The preparation and performances of the newly synthesized thin film composite (TFC) forward osmosis (FO) membranes with graphene oxide (GO)-modified support layer are presented in this study. GO nanosheets were incorporated in the polysulfone (PSf) to obtain PSf/GO composite membrane support layer. Polyamide (PA) active layer was subsequently formed on the PSf/GO by interfacial polymerization to obtain the TFC-FO membranes. Results reveal that at an optimal amount of GO addition (0.25 wt%), a PSf/GO composite support layer with favorable structural property measured in terms of thickness, porosity and pore size can be achieved. The optimum incorporation of GO in the PSF support layer not only significantly improved water permeability but also allowed effective PA layer formation, in comparison to that of pure PSf support layer which had much lower water permeability. Thus, a TFC-FO membrane with high water flux (19.77 Lm-2h-1 against 6.08 Lm-2h-1 for pure PSf) and reverse flux selectivity (5.75 Lg-1 against 3.36 Lg-1 for pure PSf) was obtained under the active layer facing the feed solution or AL-FS membrane orientation. Besides the improved structural properties (reduced structural parameter, S) of the support layer, enhanced support hydrophilicity also contributed to the improved water permeability of the membrane. Beyond a certain point of GO addition (≥0.5 wt%), the poor dispersion of GO in dope solution and significant structure change resulted in lower water permeation and weaker mechanical properties in support as well as FO flux/selectivity of consequent TFC membrane. Overall, this study suggests that GO modification of membrane supports could be a promising technique to improve the performances of TFC-FO membranes.
Tijing, LD, Woo, YC, Choi, J, Lee, S, Kim, S & Shon, HK 2015, 'Fouling and its control in membrane distillation—A review', Journal of Membrane Science, vol. 475, pp. 215-244.View/Download from: Publisher's site
Membrane distillation (MD) is an emerging thermally-driven technology that poses a lot of promise in desalination, and water and wastewater treatment. Developments in membrane design and the use of alternative energy sources have provided much improvement in the viability of MD for different applications. However, fouling of membranes is still one of the major issues that hounds the long-term stability performance of MD. Membrane fouling is the accumulation of unwanted materials on the surface or inside the pores of a membrane that results to a detrimental effect on the overall performance of MD. If not addressed appropriately, it could lead to membrane damage, early membrane replacement or even shutdown of operation. Similar with other membrane separation processes, fouling of MD is still an unresolved problem. Due to differences in membrane structure and design, and operational conditions, the fouling formation mechanism in MD may be different from those of pressure-driven membrane processes. In order to properly address the problem of fouling, there is a need to understand the fouling formation and mechanism happening specifically for MD. This review details the different foulants and fouling mechanisms in the MD process, their possible mitigation and control techniques, and characterization strategies that can be of help in understanding and minimizing the fouling problem
Woo, YC, Lee, JJ, Tijing, LD, Shon, HK, Yao, M & Kim, H-S 2015, 'Characteristics of membrane fouling by consecutive chemical cleaning in pressurized ultrafiltration as pre-treatment of seawater desalination', DESALINATION, vol. 369, pp. 51-61.View/Download from: Publisher's site
Kim, J, Jeong, K, Park, MJ, Shon, HK & Kim, JH 2015, 'Recent Advances in Osmotic Energy Generation via Pressure-Retarded Osmosis (PRO): A Review', ENERGIES, vol. 8, no. 10, pp. 11821-11845.View/Download from: Publisher's site
Nisola, GM, Limjuco, LA, Vivas, EL, Lawagon, CP, Park, MJ, Shon, HK, Mittal, N, Nah, IW, Kim, H & Chung, WJ 2015, 'Macroporous flexible polyvinyl alcohol lithium adsorbent foam composite prepared via surfactant blending and cryo-desiccation', Chemical Engineering Journal, vol. 280, pp. 536-548.View/Download from: Publisher's site
© 2015 Elsevier B.V. Macroporous polyvinyl alcohol (PVA) foam composites with high loading of uniformly distributed lithium ion sieves (LIS) were successfully fabricated and evaluated for Li+ recovery. Surfactant blending combined with cryo-desiccation effectively produced LIS/PVA foams with hierarchical porosity composed of macro- and mesopores. Glutaraldehyde cross-linking rendered the LIS/PVA foams insoluble in water but exhibited high water absorbency and flexibility. Relative to the LIS powder, the foams exhibited minimal reductions in adsorption capacity (qe) and kinetic properties due to: (1) high total porosity and surface area, (2) hydrophilicity of PVA matrix, and (3) high LIS loading, which promoted particle exposure on the foam surface. These features facilitated easy convective flow of water through the matrix and allowed intimate contact between the Li+ feed source and the LIS surface. Thus, LIS/PVA foams with high loadings (200-300wt%) exhibited meager reductions in qe (7-13%) and kinetic properties compared to the LIS powder. With LIS loading increase, Li+ selectivity of LIS/PVA foams against other cations (i.e. Na+, K+, Mg2+, Ca2+) likewise approached that of the LIS powder. While 300wt% LIS/PVA had low mechanical property, lower LIS loadings of 200- and 250wt% were highly durable and exhibited no deterioration in adsorption performance and reusability. Among the prepared LIS/PVA, 250wt% demonstrated the highest adsorption performance and can be repeatedly used for long-term application. The developed LIS/PVA foams are promising Li+ adsorbents for secondary Li+ sources; application of these foams via a simple "absorb and squeeze" mechanism could be more practical than the energy-intensive processes like packed bed and membrane systems.
Torrejos, REC, Nisola, GM, Park, MJ, Shon, HK, Seo, JG, Koo, S & Chung, W-J 2015, 'Synthesis and characterization of multi-walled carbon nanotubes-supported dibenzo-14-crown-4 ether with proton ionizable carboxyl sidearm as Li+ adsorbents', CHEMICAL ENGINEERING JOURNAL, vol. 264, pp. 89-98.View/Download from: Publisher's site
Chae, S-R, Noeiaghaei, T, Jang, H-C, Sahebi, S, Jassby, D, Shon, H-K, Park, P-K, Kim, J-O & Park, J-S 2015, 'Effects of natural organic matter on separation of the hydroxylated fullerene nanoparticles by cross-flow ultrafiltration membranes from water', SEPARATION AND PURIFICATION TECHNOLOGY, vol. 140, pp. 61-68.View/Download from: Publisher's site
Chekli, L, Galloux, J, Zhao, YX, Gao, BY & Shon, HK 2015, 'Coagulation performance and floc characteristics of polytitanium tetrachloride (PTC) compared with titanium tetrachloride (TiCl4) and iron salts in humic acid-kaolin synthetic water treatment', SEPARATION AND PURIFICATION TECHNOLOGY, vol. 142, pp. 155-161.View/Download from: Publisher's site
Kim, DI, Kim, J, Shon, HK & Hong, S 2015, 'Pressure retarded osmosis (PRO) for integrating seawater desalination and wastewater reclamation: Energy consumption and fouling', JOURNAL OF MEMBRANE SCIENCE, vol. 483, pp. 34-41.View/Download from: Publisher's site
Kim, J, Phuntsho, S, Lotfi, F & Shon, H 2015, 'Investigation of pilot-scale 8040 FO membrane module under different operating conditions for brackish water desalination', Desalination and Water Treatment, vol. 53, no. 10, pp. 2782-2791.View/Download from: Publisher's site
Two spiral wound forward osmosis membrane modules with different spacer designs (corrugated spacer [CS] and medium spacer [MS]) were investigated for the fertilizer-drawn forward osmosis (FO) desalination of brackish groundwater (BGW) at a pilot-scale level. This study mainly focused on examining the influence of various operating conditions such as feed flow rate, total dissolved solids (TDS) concentration of the BGW feed, and draw solution (DS) concentrations using ammonium sulfate ((NH4)2SO4, SOA) on the performance of two membrane modules. The feed flow rate played a positive role in the average water flux of the pilot-scale FO membrane module due to enhanced mass transfer coefficient across the membrane surface. Feed TDS and DS concentrations also played a significant role in both FO membrane modules because they are directly related to the osmotic driving force and membrane fouling tendency. CS module performed slightly better than MS module during all experiments due to probably enhanced mass transfer and lower fouling propensity associated with the CS. Besides, CS spacer provides larger channel space that can accommodate larger volumes of DS, and hence, could maintain higher DS concentration. However, the extent of dilution for the CS module is slightly lower.
Kim, Y, Lee, S, Shon, HK & Hong, S 2015, 'Organic fouling mechanisms in forward osmosis membrane process under elevated feed and draw solution temperatures', DESALINATION, vol. 355, pp. 169-177.View/Download from: Publisher's site
Lotfi, F, Phuntsho, S, Majeed, T, Kim, K, Han, DS, Abdel-Wahab, A & Shon, HK 2015, 'Thin film composite hollow fibre forward osmosis membrane module for the desalination of brackish groundwater for fertigation', DESALINATION, vol. 364, pp. 108-118.View/Download from: Publisher's site
Majeed, T, Lotfi, F, Phuntsho, S, Yoon, JK, Kim, K & Shon, H 2015, 'Performances of PA hollow fiber membrane with the CTA flat sheet membrane for forward osmosis process', Desalination and Water Treatment, vol. 53, no. 7.View/Download from: Publisher's site
Fertilizer drawn forward osmosis desalination has been earlier explored using flat sheet forward osmosis (FSFO) membrane, which highlighted flux and reverse solute flux (RSF) performance. This study evaluated and compared the performances of a newly developed polyamide (PA)-based hollow fiber forward osmosis (HFFO) membrane and cellulose triacetate FSFO membrane. Both membranes were evaluated for pure water permeability, salt rejection rate (1,000 mg/L NaCl) in RO mode. Physical structure and morphology were further examined using scanning electron micrograph (SEM). SEM images revealed that the overall thickness of the HFFO and FSFO membranes was 152 and 91 μm, respectively. Flux and RSF performances of these two membranes were evaluated using nine fertilizer DS as NH4Cl, KNO3, KCl, (NH4)2SO4, Ca(NO3)2, NH4H2PO4, (NH4)2HPO4, NaNO3, and CO(NH2)2 in active layer–feed solution membrane orientation. HFFO membrane clearly showed better performance for water flux with five DS ((NH4)2SO4, NH4H2PO4, KNO3, CO(NH2)2, and NaNO3) as they showed up to 66% increase in flux. Beside thick PA active layer of HFFO membrane, higher water flux outcome for forward osmosis (FO) process further highlighted the significance of the nature of support layer structure, the thickness and surface chemistry of the active layer of the membrane in the FO process. On the other hand, most DS showed lower RSF with HFFO membrane with the exception of Ca(NO3)2. Most of DS having monovalent cation and anions showed significantly lower RSF with HFFO membrane.
Majeed, T, Phuntsho, S, Sahebi, S, Kim, J, Yoon, JK, Kim, K & Shon, H 2015, 'Influence of the process parameters on hollow fiber forward osmosis membrane performances', Desalination and Water Treatment, vol. 54, no. 4-5, pp. 817-828.View/Download from: Publisher's site
Continued efforts are made in improving the performance of the low-cost forward osmosis (FO) membrane process which utilizes naturally available osmotic pressure of the draw solution (DS) as the driving force. Selection of a suitable DS and development of a better performing membrane remained the main research focus. In this study, the performance of a hollow fiber forward osmosis (HFFO) membrane was evaluated with respect to various operating conditions such as different cross-flow directions, membrane orientation, solution properties, and solution flow rates (Reynolds number). The study observed that operating parameters significantly affect the performance of the FO process. FO comparatively showed better performance at counter-current orientation. NaCl, KCl, and NH4Cl were evaluated as DS carrying common anion. Properties of the anionic part of the DS were found important for flux outcome, whereas reverse solute flux (RSF) was largely influenced by the properties of DS cationic part. FO was operated at different DS and feed solution (FS) flow rates and FO outcome was assessed for varying DS and FS Reynolds number ratio. FO showed better flux outcome as Re ratio for DS and FS decreases and vice versa. Results indicated that by adjusting FO processes conditions, HFFO membrane could achieve significantly lower specific RSF and higher water flux outcome. It was observed that using 2 M NaCl as DS and deionized water as FS, HFFO successfully delivered flux of 62.9 LMH which is significantly high compared to many FO membranes reported in the literature under the active layer-DS membrane orientation mode.
Park, SH, Park, B, Shon, HK & Kim, S 2015, 'Modeling full-scale osmotic membrane bioreactor systems with high sludge retention and low salt concentration factor for wastewater reclamation', BIORESOURCE TECHNOLOGY, vol. 190, pp. 508-515.View/Download from: Publisher's site
Sahebi, S, Phuntsho, S, Kim, JE, Hong, S & Shon, HK 2015, 'Pressure assisted fertiliser drawn osmosis process to enhance final dilution of the fertiliser draw solution beyond osmotic equilibrium', JOURNAL OF MEMBRANE SCIENCE, vol. 481, pp. 63-72.View/Download from: Publisher's site
Zhao, P, Gao, B, Xu, S, Kong, J, Ma, D, Shon, HK, Yue, Q & Liu, P 2015, 'Polyelectrolyte-promoted forward osmosis process for dye wastewater treatment - Exploring the feasibility of using polyacrylamide as draw solute', CHEMICAL ENGINEERING JOURNAL, vol. 264, pp. 32-38.View/Download from: Publisher's site
Zhao, P, Gao, B, Yue, Q & Shon, HK 2015, 'The performance of forward osmosis process in treating the surfactant wastewater: The rejection of surfactant, water flux and physical cleaning effectiveness', CHEMICAL ENGINEERING JOURNAL, vol. 281, pp. 688-695.View/Download from: Publisher's site
Zhao, P, Gao, B, Yue, Q, Kong, J, Shon, HK, Liu, P & Gao, Y 2015, 'Explore the forward osmosis performance using hydrolyzed polyacrylamide as draw solute for dye wastewater reclamation in the long-term process', CHEMICAL ENGINEERING JOURNAL, vol. 273, pp. 316-324.View/Download from: Publisher's site
Zhao, YX, Gao, BY, Shon, HK, Phuntsho, S & Yang, YZ 2015, 'Enhanced Coagulation of Titanium Tetrachloride Aided by the Modified Compound Bioflocculant', JOURNAL OF ENVIRONMENTAL ENGINEERING, vol. 141, no. 9.View/Download from: Publisher's site
Zhao, YX, Phuntsho, S, Gao, BY, Yang, YZ, Kim, J-H & Shon, HK 2015, 'Comparison of a novel polytitanium chloride coagulant with polyaluminium chloride: Coagulation performance and floc characteristics', JOURNAL OF ENVIRONMENTAL MANAGEMENT, vol. 147, pp. 194-202.View/Download from: Publisher's site
Kunhikrishnan, A, Shon, H, Bolan, NS, El Saliby, I & Vigneswaran, S 2015, 'Sources, distribution, environmental fate and ecological effects of nanomaterials in wastewater streams', Critical Reviews in Environmental Science and Technology, vol. 45, no. 4, pp. 277-318.View/Download from: Publisher's site
Engineered nanomaterials (ENM) are manufactured, as opposed to being an incidental by-product of combustion or a natural process, and they often have unique or novel properties that emerge from their small size. These materials are being used in an expanding array of consumer products and, like all technological developments, have both benefits and risks. As the use of ENM in consumer products becomes more common, the amount of these nanomaterials entering wastewater stream increases. Estimates of nanomaterials production are in the range of 500 and 50,000 tons per year for silver and titanium dioxide (TiO2) alone, respectively. Nanomaterials enter the wastewater stream during the production, usage, and disposal of nanomaterial-containing products. The predicted values of nanomaterials range from 0.003 (fullerenes) to 21 ng L−1 (nano-TiO2) for surface waters, and from 4 ng L−1 (fullerenes) to 4 μg L−1 (nano-TiO2) for sewage treatment effluents. Therefore, investigating the fate of nanomaterials in wastewater streams is critical for risk assessment and pollution control. The authors aim first to identify the sources of nanomaterials reaching wastewater streams, then determine their occurrence and distribution, and finally discuss their fate in relation to human and ecological health, and environmental impact.
Katz, A, McDonagh, A, Tijing, L & Shon, HK 2015, 'Fouling and inactivation of titanium dioxide-based photocatalytic systems', Critical Reviews in Environmental Science and Technology, vol. 45, no. 17, pp. 1880-1915.View/Download from: Publisher's site
Titanium dioxide is an effective photocatalyst for the breakdown of many environmental contaminants. The complex mixtures that can occur in water matrices can significantly affect the breakdown of the contaminants in water by titanium dioxide (TiO2). The authors discuss a wide variety of foulants and inhibitors of photocatalytic TiO2 systems and review different methods that can be effective for their fouling prevention. Approaches to regenerate a fouled or contaminated TiO2 catalysts are explored and the effect of substrates on immobilized titanium dioxide is also reviewed.
Shahid, M, Saliby, IE, Tijing, LD, McDonagh, A, Park, SM, Lee, KY, Shon, HK & Kim, J 2015, 'Synthesis and Characterisation of Silica-Modified Titania for Photocatalytic Decolouration of Crystal Violet', Journal of Nanoscience and Nanotechnology, vol. 15, no. 7, pp. 5326-5329.View/Download from: Publisher's site
In the past few years, silica-modified titania has drawn increasing attention due to their special properties making them ideal candidates for a wide range of applications. In this study, we report a novel method for the synthesis of silica-modified titania by a sol–gel method using sodium silicate solution (1 M). The hydrolysis and condensation reactions of titanium dioxide (TiO2, Degussa Aeroxide® P25) in sodium silicate solution proceeded with citric acid (3 M) as a catalyst. The orbital shaking method was followed for the removal of sodium salt formed during the sol–gel process. Solvent exchange was carried out using methanol and hexane. Finally, chemical modification of the gel was conducted using trimethylchlorosilane followed by ambient pressure drying. The obtained silica-modified titania was characterised for nanostructural analysis using scanning electron microscopy and transmission electron microscopy. The nitrogen adsorption–desorption measurements were employed to investigate the BET surface area, pore structure and pore volume of specimens. Thermal gravimetric analysis showed exothermic peaks at temperature range of 90–190 °C representing the oxidation of organic groups from –Si–R network. The silica-modified titania showed high photocatalytic activity and an easy recovery using crystal violet as model water pollutant.
Shahid, M, Shon, HK, McDonagh, A & Kim, JH 2015, 'Magnetised titanium dioxide (TiO2) for water purification: preparation, characterisation, and application', Desalination and Water Treatment, vol. 54, no. 4-5, pp. 979-1002.View/Download from: Publisher's site
The study of titanium dioxide (TiO2) as a photocatalyst for water purification has attracted significant attention over the past four decades. However, the separation of photocatalyst from water suspension may be difficult, costly and jeopardise the use of this water treatment technology. Recently, the development and production of magnetised TiO2 have been achieved to offer a solution for the photocatalyst separation problem. This paper discusses the preparation techniques, characterisation and the applications of magnetised TiO2. Many researchers have studied magnetised TiO2 photocatalysts but the lack of articles discussing the water purification processes is still slowing any advance in this field. Here, the progress of the scientific research on preparation techniques to coat magnetic particles by materials such as organic polymers, silica, magnesia, and alumina are reviewed to compare and discuss recent findings. The doping of photoactive TiO2 photocatalyst into the magnetic-coated particles is also emphasised. In addition, the characterisation of magnetised TiO2 in terms of physicochemical properties and operating conditions produced by each technique are critically reviewed. Moreover, examples of applications of TiO2 and magnetised TiO2 photocatalyst in water purification are summarised. In general, the effectiveness of organic removal by magnetised TiO2 is still lower compared to single phase TiO2. The future prospect of this field is deliberated to develop a novel, economic and efficient magnetised TiO2 photocatalyst, which has high organic removal properties.
Amarjargal, A, Tijing, LD, Shon, HK, Park, C & Kim, CS 2014, 'Facile in situ growth of highly monodispersed Ag nanoparticles on electrospun PU nanofiber membranes: Flexible and high efficiency substrates for surface enhanced Raman scattering', Applied Surface Science, vol. 308, pp. 396-401.
Chekli, L, Phuntsho, S, Tijing, LD, Zhou, JL, Kim, J-H & Shon, HK 2014, 'Stability of Fe-oxide nanoparticles coated with natural organic matter under relevant environmental conditions', Water Science & Technology, vol. 70, no. 12, pp. 2040-2046.View/Download from: Publisher's site
Manufactured nanoparticles (MNPs) are increasingly released into the environment and thus research on their fate and behaviour in complex environmental samples is urgently needed. The fate of MNPs in the aquatic environment will mainly depend on the physico-chemical characteristics of the medium. The presence and concentration of natural organic matter (NOM) will play a significant role on the stability of MNPs by either decreasing or exacerbating the aggregation phenomenon. In this study, we firstly investigated the effect of NOM concentration on the aggregation behaviour of manufactured Fe-oxide nanoparticles. Then, the stability of the coated nanoparticles was assessed under relevant environmental conditions. Flow field-flow fractionation, an emerging method which is gaining popularity in the field of nanotechnology, has been employed and results have been compared to another size-measurement technique to provide increased confidence in the outcomes. Results showed enhanced stability when the nanoparticles are coated with NOM, which was due to electrosteric stabilisation. However, the presence of divalent cations, even at low concentration (i.e. less than 1 mM) was found to induce aggregation of NOM-coated nanoparticles via bridging mechanisms between NOM and Ca2+
Park, C, Tijing, LD, Shon, HK & KIMa, CHEOLSANG 2014, 'SILICONE-COATINGOF NITINOL STENT WIRES BY ELECTROSPINNING: CATHETER DEPLOYMENT TEST', Digest Journal of Nanomaterials & Biostructures (DJNB), vol. 9, no. 1.
Subagia, IDGA, Jiang, Z, Tijing, LD, Kim, Y, Kim, CS, Lim, JK & Shon, HK 2014, 'Hybrid multi-scale basalt fiber-epoxy composite laminate reinforced with Electrospun polyurethane nanofibers containing carbon nanotubes', Fibers and Polymers, vol. 15, no. 6, pp. 1295-1302.View/Download from: Publisher's site
Subagia, IDGA, Kim, YJ, Tijing, LD, Kim, CS & Shon, H 2014, 'Effect of stacking sequence on the flexural properties of hybrid composites reinforced with carbon and basalt fibers', Composites: Part B, vol. 58, pp. 251-258.View/Download from: Publisher's site
We investigated the effect of different stacking sequences of carbon and basalt fabrics on the flexural properties of hybrid composite laminates. The hybrid composites were fabricated using a vacuum-assisted resin transfer molding process. Three-point bending test was performed and the fracture surfaces were examined by scanning electron microscopy. The present results showed that the flexural strength and modulus of hybrid composite laminates were strongly dependent on the sequence of fiber reinforcement. All the stacking sequences showed a positive hybridization effect. The interply hybrid composite with carbon fiber at the compressive side exhibited higher flexural strength and modulus than when basalt fabric was placed at the compressive side. Here, the proper stacking sequence of basalt and carbon fiber layers was found to improve the balance of the mechanical properties of the hybrid composite laminate.
Tijing, LD, Choi, J-S, Lee, S, Kim, S-H & Shon, HK 2014, 'Recent progress of membrane distillation using electrospun nanofibrous membrane', Journal of Membrane Science, vol. 453, pp. 435-462.View/Download from: Publisher's site
Rapid population growth has resulted in imbalance in the supply and demand of fresh water for human consumption. As the sources of fresh water from surface water and fresh groundwater have been consistently depleting at an alarming rate, alternative sources such as seawater and brackish water are sought out. Desalination of water is considered as one of the most sustainable and best water resource alternatives. Membrane distillation (MD) is an emerging and promising technology for water desalination and purification. It presents many advantages over the common desalination technologies such as reverse osmosis. The two major factors hindering the application of MD are suitable membrane design and structure, and energy efficiency of the MD process. In recent years, membrane design has seen increasing research and interest. Advances in science and technology have led to new materials and techniques that could find potential application for membranes in MD. In the past few years, electrospinning of nanofibers has gained much interest and attention in their application for MD membrane, and so far has promising results. This review focuses on the recent progress in the application of nanofibrous membrane fabricated by electrospinning for MD application.
Tijing, LD, Shon, H, Ary Subagia, IDG, Kim, Y, Kim, CS & Vista Iv, FP 2014, 'Mechanical performance of multiscale basalt fiberepoxy laminates', Composites Part B: Engineering, vol. 58, pp. 611-617.View/Download from: Publisher's site
In this study, the effect of different tourmaline (TM) micro/nano particle loading (i.e., 0.5–2 wt%) on the tensile and flexural properties of a basalt fiber-reinforced epoxy composite laminate (BFRP) was investigated. The TM/basalt/epoxy laminates were fabricated by impregnating woven basalt fibers into epoxy resin mixed with TM particles via vacuum assisted resin transfer molding. Tensile and flexural tests were performed according to ASTM standards. Fracture surfaces were characterized by scanning electron microscopy and energy dispersive spectroscopy. The results showed significant improvement in both tensile and flexural strength and modulus when tourmaline particles where incorporated in the basalt/epoxy composite. The best result was obtained at 1 wt% TM loading with surfactant (i.e., C4) showing an increase of ∼16% in both tensile and flexural strength, and 27.4% and 153.3% increase in tensile and flexural modulus, respectively, compared to neat basalt/epoxy composite. The enhanced performance of TM/basalt/epoxy laminates is attributed to a good dispersion of TM particles in the epoxy matrix providing increased surface area for strong interfacial interaction and good load transfer.
Tijing, LD, Shon, HK, Park, CH, Kim, EK, Amarjargal, A, Pant, HR & Kim, CS 2014, 'Preparation and characterization of LA/PCL composite fibers containing beta tricalcium phosphate (β-TCP) particles', Ceramics International, vol. 40, no. 3, pp. 5049-5054.View/Download from: Publisher's site
Beta-TCP (β-TCP) particle-containing LA/PCL micro/nanofibers were fabricated via a one-step electrospinning process. The morphology and chemical structure of the composite nanofibers were characterized by FESEM, XRD, and FTIR. Rougher surfaces were observed for the LA/PCL micro/nanofibers containing β-TCP compared to the neat LA/PCL fibers, which could possibly provide extra sites for cell binding. XRD and FTIR confirmed the presence of β-TCP as being firmly deposited on the fibers. After an immersion in distilled water, we observed that the β-TCP-containing composite fibers were more degradable with many damaged and broken fibers compared to the LA/PCL fibers. MTT assay and immersion test showed better cell viability and proliferation, and improved mineralization ability compared to the LA/PCL only mat. Thus, the incorporation of β-TCP and the presence of LA in PCL micro/nanofibers could result to an improved biocompatibility and faster degradation of the composite fibers, which would possibly be useful for tissue scaffold application.
Tijing, LD, Woo, Y, Johir, M, Choi, JS & Shon, H 2014, 'A novel dual-layer bicomponent electrospun nanofibrous membrane for desalination by direct contact membrane distillation', Chemical Engineering Journal, vol. 256, pp. 155-159.View/Download from: Publisher's site
In this study, a bicomponent nanofibrous composite membrane was fabricated by electrospinning and was tested for desalination by direct contact membrane distillation (DCMD). The nanofibrous membrane was composed of a dual-layered structure of poly(vinylidene fluoride-co-hexafluoropropylene) (PH) nanofibers and polyacrylonitrile (PAN) microfibers. Morphological characterization showed slightly beaded cylindrical PH nanofibers with porosity of about 90%. The contact angles of PH and PAN nano/microfibers were 150 degrees and 100 degrees, respectively. The nanofibrous membranes were tested by DCMD and a high water flux of 45 and 30 L m(-2) h(-1) was obtained for distilled water and 35 g L-1 NaCl solutions as feed, respectively using DL2 membrane (i.e., 25/75 PH/PAN thickness ratio). The present dual-layer membrane showed better flux performance compared to a commercial flat-sheet membrane. The results suggest the potential of the dual-layer nanofibrous membrane for DCMD applications
Fam, W, Phuntsho, S, Lee, JH, Cho, J & Shon, H 2014, 'Boron transport through polyamide-based thin film composite forward osmosis membranes', Desalination, vol. 340, pp. 11-17.View/Download from: Publisher's site
The boron transport in forward osmosis (FO) process using thin film composite (TFC) membranes has been investigated. Two common fertilizers were used as draw solutes and a model seawater as the feed. The influence of several physical and chemical operating conditions on boron solute flux and boron rejection rates was investigated. The examined factors include draw solution types, membrane orientation, feed and draw solution concentrations, boron feed concentration, crossflow rate, and feed solution pH. The key mechanisms that govern boron transports are reverse draw solute flux and internal concentration polarization experienced by the membrane during the FO process. Results show that the use of draw solute with small hydrated radius could improve boron rejection hindered by the higher reverse diffusion of draw solutes. The osmotic process operated in the pressure retarded osmosis (PRO) mode results in lower boron rejection. However, the most effective boron removal was achieved by operating the feed solution at high pH (pH = 11) because boron in the solution contains larger-size borate species, and thus increases boron rejection rate up to 94% by electrostatic repulsion. This study mainly focused on the performance of TFC membrane in boron removal.
Kim, Y, Elimilech, M, Shon, H & Hong, SK 2014, 'Combined organic and colloidal fouling in forward osmosis: Fouling reversibility and the role of applied pressure', Journal of Membrane Science, vol. 460, pp. 206-212.View/Download from: Publisher's site
In this study, we systematically investigated the propensity and reversibility of combined organic–colloidal fouling in forward osmosis (FO) under various solution chemistries (pH and calcium ion concentrations) and applied hydraulic pressure on the feed side. Alginate, silica colloids, and their mixture (i.e., combined organic–colloidal) were used as model foulants. Our findings demonstrate that combined organic–colloidal foulants caused more rapid flux decline than the individual foulants due to the synergistic effect of alginate and silica colloids. As a result, much lower flux recovery was achieved by physical cleaning induced by increasing the cross-flow rate, in contrast to single foulants of which the fouling layer was easily removed under all solution conditions. Interestingly, less flux decline was observed at neutral pH for combined fouling, while acidic conditions were favorable for alginate fouling and basic solutions caused more silica fouling, thereby providing clear evidence for the combined fouling effect. It was also found that calcium ions enhanced water flux decline and induced the formation of less reversible combined organic–colloidal fouling layers. Lastly, the role of applied hydraulic pressure on the feed side in FO was examined to elucidate the mechanism of fouling layer formation, fouling reversibility, and water flux recovery. Higher fouling propensity and lower fouling reversibility of combined organic–colloidal fouling were observed in the presence of applied hydraulic pressure on the feed side. This observation suggests that the lower fouling propensity and greater fouling reversibility in FO compared to reverse osmosis (RO), are attributable to unpressurized operating conditions in FO.
Liu, P, Gao, B, Shon, HK, Ma, D, Rong, H, Zhao, P, Zhao, S, Yue, Q & Li, Q 2014, 'Water flux behavior of blended solutions of ammonium bicarbonate mixed with eight salts respectively as draw solutions in forward osmosis', DESALINATION, vol. 353, pp. 39-47.View/Download from: Publisher's site
Nateghi Ghasemian Nejad, F, Shon, H & Khabbaz, H 2014, 'Development of a new poly silicate ferric coagulant and its application to coagulation-membrane filtration hybrid system in wastewater treatment', Desalination and Water Treatment, vol. 52, no. 4-6, pp. 663-669.View/Download from: Publisher's site
Coagulation is one of the effective pretreatment stages in membrane filtration of wastewaters to produce clean water. Using a suitable coagulant, one can mitigate membrane fouling. Membrane fouling is a process where particles deposit onto a membrane surface or into membrane pores in a way that degrades the membrane’s performance. Research in this area is currently being focused on development of improved coagulation reagents such as poly silicate ferric (PSiFe), which has a high molecular weight and large number of positive surface charges with high efficiency at low doses. In this paper, PSiFe was prepared by following two approaches: (a) acidification of water glass solution using HCl followed by FeCl3 addition (old-PSiFe); (b) acidification of water glass solution by passing it through an acidic ion exchange resin followed by fresh FeCl3 addition under different Fe/Si molar ratios (new-PSiFe). These coagulants were characterised by X-ray diffraction and scanning electron microscopy. According to coagulation jar test results when Fe/Si = 1, the best performance was achieved in terms of turbidity, total organic carbon (TOC) and UV254 removals. Another aspect is the comparison of the old-PSiFe, FeCl3 and new-PSiFe which showed that in a membrane filtration system, using the new-PSiFe not only reduces the required transmembrane pressure (TMP) due to lower fouling, but also improves the TOC removal efficiency.
Phuntsho, S, Shon, HK, Hong, S & Elimelech, M 2014, 'Osmotic equilibrium in the forward osmosis process: Modelling, experiments and implications for process performance', Journal of Membrane Science, vol. 453, pp. 240-252.View/Download from: Publisher's site
Forward osmosis (FO) has gained significant research interest due to the wide range of potential applications in desalination and wastewater reuse. However, the FO process being concentration (osmosis) driven has its own intrinsic limitations. Net transfer of water across the membrane occurs until the point of osmotic equilibrium between the draw solution (DS) and the feed solution (FS). Without external intervention, it is impossible to dilute the DS beyond the point of osmotic equilibrium. In this study, the concept of osmotic equilibrium in the FO process is introduced by simulating conditions in a plate-and-frame FO membrane module using established mass transport models. The simulations evaluated the influence of various operating parameters on process performance, assessed in terms of water flux, feed recovery rate and the final concentration of the diluted DS. The counter-current crossflow mode of operation has been observed to be advantageous because it can achieve higher module average water flux, higher feed water recovery rates and higher DS final dilution. Based on the osmotic equilibrium concept and mass balance analysis, a modified equation for the water extraction capacity of a draw solute has been proposed. This study underscores the need for process optimisation for large-scale FO operations.
Shon, HK, Chekli, L, Park, SM, Kim, JB, Shahid, M, Kim, PS, Lee, WS, Lee, WE & Kim, JH 2014, 'NOx removal on mortar mixed with titania produced from Ti-salt flocculated sludge', Journal of Industrial and Engineering Chemistry, vol. 20, no. 5, pp. 3851-3856.View/Download from: Publisher's site
Norms for the emissions of NOx are becoming stricter and stricter, leading to an increase in the research interest for the development of novel gas cleaning technologies. In this study, the use of titania (TiO2) produced from Ti-salt flocculated sludge, mixed with mortar, has been investigated as a cost-effective novel solution for the removal of these pollutant gases. This work not only presents an advanced solution for sludge reduction but also proposes a novel production method of TiO2 powders from waste water and investigates the potential use of this material blinded with mortar for a novel application which is air purification. Detailed characterization of the produced TiO2 powders was performed and results showed that the primary particles present a uniform size and spherical shape with a diameter of less than 50 nm. The main constitutive elements were Ti, O, C and P, where the Ti content was found to increase slightly with increasing temperature. The anatase phase was observed at 600 °C and 800 °C and converted to rutile structure at 1000 °C. Two contents (i.e. 3.0 and 5.0 wt%) of TiO2 were tested for mixing with mortar and photocatalytic properties of the mortar containing TiO2 were evaluated for the removal of NOx and were found to be similar to commercial TiO2 (P-25) in terms of photocatalytic activity. Further investigations under direct sunlight were conducted after 28 days of water curing to evaluate the removal of NOx. The NO rejection was about 50% after 5 h.
Shon, HK, Lee, E & Cho, J 2014, 'Role of wetland organic matters as photosensitizer for degradation ofmicropollutants and', Journal of Hazardous Materials, vol. 276, pp. 1-9.View/Download from: Publisher's site
Overall photodegradation of pharmaceuticals, personal care products (PPCPs) and pharmaceutical metabolites were investigated in order to evaluate their photochemical fate in aquatic environments in various natural organic matter (NOM) enriched solutions. Tested PPCPs exhibited different rates of loss during direct and indirect photolysis. Here, only ultraviolet (UV) light source was used for direct photolysis and UV together with 3DOM*for indirect photolysis. Diclofenac and sulfamethoxazole were susceptible to photodegradation, whereas carbamazepine, caffeine, paraxanthine and tri(2-chloroethyl) phosphate (TCEP) showed low levels of photodegradation rate, reflecting their conservative photoreactivity. During indirect photodegradation, in contrast to the hydrophilic autochthonous NOM, allochthonous NOM with relatively high molecular weight (MW), specific ultraviolet absorbance (SUVA) and hydrophobicity (e.g., Suwannee River humic acid (SRHA)) revealed to significantly inhibit the photolysis of target micropollutants. The presence of Typha wetland NOM enhanced the indirect photolysis of well-known conservative micopollutants (carbamazepine and paraxanthine). And atenolol, carbamazepine, glimepiride, and N-acetyl-sulfamethoxazole were found to be sensitive to the triplet excited state of dissolved organic matter (3DOM*) with Typha wetland NOM under deoxygenated condition. This suggests that photolysis in constructed wetlands connected to the wastewater treatment plant can enhance the degradation of some anthropogenic micropollutants by the interaction with 3DOM* in wetlands.
Shon, HK, Okour, Y, Park, SM, Kim, JB & Kim, JH 2014, 'Titania produced from Ti-salt flocculated sludge: Photocatalytic activity under solar light', Journal of Nanoscience and Nanotechnology, vol. 14, pp. 6386-6389.View/Download from: Publisher's site
In this study, titania photocatalyst was produced from the wastewater sludge of Ti-salt flocculation. The high photocatalytic activity of titania reported was evaluated based on a single organic subs-trate. However, the photocatalytic activity is a substrate-specific; one photocatalyst showed different photocatalytic degradation rates for different substrates. Thus, to investigate the substrate-specific photocatalytic activity of titania, various substrates of humic acid (HA), dichloroacetic acid (DCA), rhodamine B (RhB), metsulfuron methyl (M&M) and phenol were used under simulated solar light irradiation. Results showed titania had a high activity rate for RhB, moderate activity for HA and DCA and low activity for M&M and phenol indicating substrate-specific activities. When compared with Degussa-P25, titania showed higher activity for M&M, while the opposite was observed for HA and phenol. The specific-substrate behaviour of titania could depend on specific physicochemical and electronic interactions between titania, substrates, and their intermediates compounds formed.
Shon, HK, Phuntsho, S, Lotfi, F, Elimelech, M, Shaffer, DL & Hong, S 2014, 'Membrane scaling and flux decline during fertiliser-drawn forward osmosis desalination of brackish groundwater', Water Research, vol. 57, pp. 172-182.View/Download from: Publisher's site
Fertiliser-drawn forward osmosis (FDFO) desalination has been recently studied as one feasible application of forward osmosis (FO) for irrigation. In this study, the potential of membrane scaling in the FDFO process has been investigated during the desalination of brackish groundwater (BGW). While most fertilisers containing monovalent ions did not result in any scaling when used as an FO draw solution (DS), diammonium phosphate (DAP or (NH4)2HPO4) resulted in significant scaling, which contributed to severe flux decline. Membrane autopsy using scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), and x-ray diffraction (XRD) analysis indicated that the reverse diffusion of DAP from the DS to the feed solution was primarily responsible for scale formation during the FDFO process. Physical cleaning of the membrane with deionised water at varying crossflow velocities was employed to evaluate the reversibility of membrane scaling and the extent of flux recovery. For the membrane scaled using DAP as DS, 80–90% of the original flux was recovered when the crossflow velocity for physical cleaning was the same as the crossflow velocity during FDFO desalination. However, when a higher crossflow velocity or Reynolds number was used, the flux was recovered almost completely, irrespective of the DS concentration used. This study underscores the importance of selecting a suitable fertiliser for FDFO desalination of brackish groundwater to avoid membrane scaling and severe flux decline.
Zhao, P, Yue, Q, Gao, B, Kong, J, Rong, H, Liu, P, Shon, H & Li, Q 2014, 'Influence of different ion types and membrane orientations on the forward osmosis performance', Desalination, vol. 344, pp. 123-128.View/Download from: Publisher's site
This study investigated the influence of different ions on forward osmosis (FO) performance in terms of water flux. NaCl, NaNO3, KCl, KNO3, NH4Cl, NH4NO3, CaCl2 and Ca(NO3)2 were selected as representatives of draw solutions (DSs). Data were obtained from laboratory-scale experiments under well controlled conditions in both membrane orientations operated in FO mode pressure retarded osmosis (PRO) mode. The basic properties of DS (osmotic potential, viscosity, diffusion coefficient) changed the water and reverse salt transmission. The results indicated that the performance of one solution in different modes was different. The behavior of Na+ and K+ salts was quite satisfactory in the PRO mode; specifically NaCl had the greatest water flux (16.96 L/(m2 h)), and the following largest was KCl (16.55 L/(m2 h)). K+ salts had the highest water flux among all the selected positive ions in the FO mode which was KCl (10.30 L/(m2 h)). To the negative ions, Cl− salts showed higher water flux than nitrates in both PRO and FO modes, such as the water flux of NaNO3 was 7.96 L/(m2 h), while that of NaCl was 8.86 L/(m2 h) in the FO mode. Overall, K+ and Cl− were regarded as optimal candidates of cation and anion, respectively.
Zhao, YB, Gao, BY, Zhang, GZ, Phuntsho, S & Shon, H 2014, 'Coagulation by titanium tetrachloride for fulvic acid removal: Factors influencing coagulation efficiency and floc characteristics', Desalination, vol. 335, pp. 70-77.View/Download from: Publisher's site
Coagulation efficiency of titanium tetrachloride (TiCl4) was investigated for fulvic acid (FA) (as model organic matter) removal compared to traditional coagulants — iron chloride (FeCl3) and aluminum sulfate (Al2(SO4)3). The growth, breakage and regrowth nature of flocs formed by the three coagulants were also comparatively evaluated under different coagulation conditions. Results indicated that TiCl4 achieved higher removal of UV278 (absorbance at 278 nm) and DOC (dissolved organic carbon) than FeCl3 and Al2(SO4)3, and TiCl4 produced the largest flocs with the highest floc growth rate. The responses of floc to different operating parameters depend on the coagulant used, while the floc breakage and re-aggregation were also significantly influenced by shear force and break-up period. Floc strength decayed with the increasing shear force, while the inverse trend was observed for floc recoverability. An extension in break-up period resulted in the deterioration of both floc strength and recoverability regardless of the coagulants used. Flocs formed by TiCl4 displayed the weakest recoverability after breakage by contrast to conventional coagulants. Since TiCl4 is only studied recently as a novel coagulant, the comparative study of coagulation performance and floc characteristics of TiCl4 against the traditional coagulants provided valuable information for its wide application in the future.
Zhao, YX, Gao, BY, Zhang, GZ, Qi, QB, Wang, Y, Phuntsho, S, Kim, J-H, Shon, H, Yue, QY & Li, Q 2014, 'Coagulation and sludge recovery using titanium tetrachloride', Separation and Purification Technology, vol. 130, pp. 19-27.View/Download from: Publisher's site
Coagulation/flocculation performance of titanium tetrachloride (TiCl4), ferric chloride (FeCl3) and aluminum sulfate (Al2(SO4)3) was comparatively investigated for real water treatment. Comparisons were made under different coagulant dose and initial solution pH conditions and their performances measured in terms of UV254 (absorbance at 254 nm) and DOC (dissolved organic carbon) removal and residual turbidity. Characteristics of aggregated flocs during the coagulation/flocculation process by the three coagulants were studied using a laser diffraction particle sizing device. The performances of the three coagulants were also assessed in terms of the membrane fouling potential of the ultrafiltration (UF) membrane or during coagulation–ultrafiltration (C–UF) process using a stirred and dead-end batch UF unit. Additionally, the TiCl4 flocculated sludge was recovered to produce titanium dioxide (TiO2) under thermal treatment. The results indicate that the TiCl4 showed superior coagulation performance compared to that of FeCl3 and Al2(SO4)3, with the optimum removal of UV254 and DOC of 54.9% and 55.1%, respectively. The aggregated flocs formed by TiCl4 showed the highest growth rate with the largest size compared to those by FeCl3 and Al2(SO4)3, but with the weakest floc strength and the worst re-growth ability. The TiCl4 and FeCl3 yielded the flocs with comparable degree of compaction, higher than that by Al2(SO4)3. Additionally, the investigation of membrane fouling demonstrated that the severity of flux decline followed the order of Al2(SO4)3 < FeCl3 < TiCl4. TiCl4 coagulated sludge was also characterized by X-ray diffraction, Thermal analysis and scanning electron microscope.
Zhao, YX, Shon, H, Phuntsho, S & Gao, BY 2014, 'Removal of natural organic matter by titanium tetrachloride: The effect of total hardness and ionic strength', Journal of Environmental Management, vol. 134, pp. 20-29.View/Download from: Publisher's site
This study is the first attempt to investigate the effect of total hardness and ionic strength on coagulation performance and the floc characteristics of titanium tetrachloride (TiCl4). Membrane fouling under different total hardness and ionic strength conditions was also evaluated during a coagulation–ultrafiltration (C–UF) hybrid process. Coagulation experiments were performed with two simulated waters, using humic acid (HA, high molecular weight) and fulvic acid (FA, relatively low molecular weight), respectively, as model natural organic matter (NOM). Results show that both particle and organic matter removal can be enhanced by increasing total hardness and ionic strength. Floc characteristics were significantly influenced by total hardness and ionic strength and were improved in terms of floc size, growth rate, strength, recoverability and compactness. The results of the UF tests show that the pre-coagulation with TiCl4 significantly improves the membrane permeate fluxes. Under different total hardness and ionic strength conditions, the membrane permeate flux varied according to both NOM and floc characteristics. The increase in total hardness and ionic strength improved the membrane permeate flux in the case of HA simulated water treatment.
Kazner, C, Jamil, S, Phuntsho, S, Shon, H, Wintgens, T & Vigneswaran, S 2014, 'Forward osmosis for the treatment of reverse osmosis concentrate from water reclamation: process performance and fouling control.', Water Science and Technology, vol. 69, no. 12, pp. 2431-2437.View/Download from: Publisher's site
While high quality water reuse based on dual membrane filtration (membrane filtration or ultrafiltration, followed by reverse osmosis) is expected to be progressively applied, treatment and sustainable management of the produced reverse osmosis concentrate (ROC) are still important issues. Forward osmosis (FO) is a promising technology for maximising water recovery and further dewatering ROC so that zero liquid discharge is produced. Elevated concentrations of organic and inorganic compounds may act as potential foulants of the concentrate desalting system, in that they consist of, for example, FO and a subsequent crystallizer. The present study investigated conditions under which the FO system can serve as concentration phase with the focus on its fouling propensity using model foulants and real ROC. Bulk organics from ROC consisted mainly of humic acids (HA) and building blocks since wastewater-derived biopolymers were retained by membrane filtration or ultrafiltration. Organic fouling of the FO system by ROC-derived bulk organics was low. HA was only adsorbed moderately at about 7% of the initial concentration, causing a minor flux decline of about 2–4%. However, scaling was a major impediment to this process if not properly controlled, for instance by pH adjustment or softening
El Saliby, I, Erdeib, L, McDonagh, A, Kim, JB, Kim, JH & Shon, HK 2014, 'Co-doped mesoporous titania photocatalysts prepared from a peroxo-titanium complex solution', Materials Research Bulletin, vol. 49, pp. 7-13.View/Download from: Publisher's site
In this study, nitrogen doped and nitrogen/silver co-doped TiO2 photocatalsysts were fabricated using a sol–gel method at room temperature. The obtained gels were neutralized, washed with pure water, and calcined at 400 °C for 4 h. The photocatalysts were characterized by scanning and transmission electron microscopy, X-ray diffraction, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, and BET specific surface area. The results showed that spherical particles with anatase structure were produced after annealing at 400 °C. N 1s (400 eV) and Ag 3d (367.3 eV) states indicated that nitrogen doping and silver co-doping were in the form of NO bonds and AgO, respectively. The photocatalytic activity of photocatalysts was investigated using a batch reactor system exposed to artificial solar irradiation. Both nitrogen and silver/nitrogen co-doped materials were effective in the photocatalytic degradation of hexamethyl pararosaniline chloride.
Shahid, M, El Saliby, I, McDonagh, A, Tijing, LD, Kim, J & Shon, HK 2014, 'Synthesis and characterisation of potassium polytitanate for photocatalytic degradation of crystal violet', Journal of Environmental Sciences, vol. 26, no. 11, pp. 2348-2354.View/Download from: Publisher's site
Potassium titanate nanostructures were synthesised by hydrothermal treatment of TiO2 (P25) in KOH and H2O2. As-produced powders were characterised by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, and nitrogen adsorption-desorption methods. Longitudinally-oriented-wire-like structures with a length up to several micrometres and diameters ranging from 10 to 30 nm were obtained. Larger size fibrous nanowires resulting from the hydrothermal treatment showed high affinity in adsorbing crystal violet (CV), which was mainly due to their high surface area. The photocatalytic bleaching of CV solution revealed that the wires are photoactive under ultraviolet light irradiation. Macroporous nanowires are considered as effective adsorbents of CV, capable of photocatalytic degradation, and they can be easily separated from the solution by settling.
Shahid, M, El Saliby, I, McDonagh, AM, Kim, JH & Shon, H 2014, 'Photodesorption of specific organic compounds from titanium dioxide particles in aqueous media', Desalination and Water Treatment, vol. 52, no. 4-6, pp. 867-872.View/Download from: Publisher's site
This study investigates the photodesorption of organic compounds (beef extract, peptone, humic acid, tannic acid, sodium lignin sulphonate, sodium lauryl sulphate, arabic gum powder and arabic acid) from TiO2 (1 g/L in water, pH 7). After a period to reach adsorption equilibrium, photodesorption experiments were conducted in a recirculated reactor at a constant flow rate of 150 mL/min with a UV light intensity of 24 W. Photodesorption was observed only for sodium lauryl sulphate (50%), sodium lignin sulphonate (43.47%), beef extract (20.35%) and tannic acid (10.5%) indicating that photodesorption is specific to some organic compounds but not to all. Using liquid chromatography-organic carbon detection, untreated beef extract and sodium lignin sulphonate were found to contain significant amounts of humic substances (∼1,000 g/mol), which decreased in concentration after dark phase adsorption, while a significant increase in low molecular weight (<350 g/mol) concentrations was observed after photodesorption. UV-treated sodium lauryl sulphate photodesorbed to give both higher molecular weight (HMW) and lower molecular weight (LMW) organics. Thus, the HMW fractions of organic compounds decomposed into smaller compounds after UV irradiation, which subsequently desorbed from TiO2 surface. However, untreated tannic acid contained a larger proportion of LMW acids, which shows a high adsorption affinity to TiO2 during adsorption and poorly desorbs upon irradiation.
Chekli, L, Phuntsho, S, Roy, M & Shon, H 2013, 'Characterisation of Fe-oxide nanoparticles coated with humic acid and Suwannee River natural organic matter', The Science of the Total Environment, vol. 461-462, pp. 19-27.View/Download from: Publisher's site
Iron oxide nanoparticles are becoming increasingly popular for various applications including the treatment of contaminated soil and groundwater; however, their mobility and reactivity in the subsurface environment are significantly affected by their tendency to aggregate. One solution to overcome this issue is to coat the nanoparticles with dissolved organic matter (DOM). The advantages of DOM over conventional surface modifiers are that DOM is naturally abundant in the environment, inexpensive, non-toxic and readily adsorbed onto the surface of metal oxide nanoparticles. In this study, humic acid (HA) and Suwannee River natural organic matter (SRNOM) were tested and compared as surface modifiers for Fe2O3 nanoparticles (NPs). The DOM-coated Fe2O3 NPs were characterised by various analytical methods including: flow field-flow fractionation (FlFFF), high performance size exclusion chromatography (HPSEC) and Fourier transform infrared spectroscopy (FTIR). The stability of the coated NPs was then evaluated by assessing their aggregation and disaggregation behaviour over time. Results showed that both HA and SRNOM were rapidly and readily adsorbed on the surface of Fe2O3 NPs, providing electrosteric stabilisation over a wide range of pH. HPSEC results showed that the higher molecular weight components of DOM were preferentially adsorbed onto the surface of Fe2O3. As SRNOM consists of macromolecules with a higher molecular weight than HA, the measured size of the SRNOM-coated Fe2O3 NPs was 30% larger than the HA-coated Fe2O3 NPs. FTIR results indicated the occurrence of hydrogen bonding arising from electrostatic interaction between the DOM and Fe2O3 NPs. Finally, a stability study showed that after 14 days, small agglomerates and aggregates were formed. The HA-coated Fe2O3 NPs formed agglomerates which were easily disaggregated using a vortex mixer, with the coated NPs returning to their initial size. However, SRNOM-coated Fe2O3 NPs were only partially disaggregated...
Chekli, L, Phuntsho, S, Roy, M, Lombi, E, Donner, E & Shon, H 2013, 'Assessing the aggregation behaviour of iron oxide nanoparticles under relevant environmental conditions using a multi-method approach', Water Research, vol. 47, no. 13, pp. 4585-4599.View/Download from: Publisher's site
Iron nanoparticles are becoming increasingly popular for the treatment of contaminated soil and groundwater; however, their mobility and reactivity in subsurface environments are significantly affected by their tendency to aggregate. Assessing their stability under environmental conditions is crucial for determining their environmental fate. A multi-method approach (including different size-measurement techniques and the DLVO theory) was used to thoroughly characterise the behaviour of iron oxide nanoparticles (Fe2O3NPs) under environmentally relevant conditions. Although recent studies have demonstrated the importance of using a multi-method approach when characterising nanoparticles, the majority of current studies continue to use a single-method approach. Under some soil conditions (i.e. pH 7, 10 mM NaCl and 2 mM CaCl2) and increasing particle concentration, Fe2O3NPs underwent extensive aggregation to form large aggregates (>1 µm). Coating the nanoparticles with dissolved organic matter (DOM) was investigated as an alternative green solution to overcoming the aggregation issue instead of using the more commonly proposed polyelectrolytes. At high concentrations, DOM effectively covered the surface of the Fe2O3NPs, thereby conferring negative surface charge on the particles across a wide range of pH values. This provided electrostatic stabilisation and considerably reduced the particle aggregation effect. DOM-coated Fe2O3NPs also proved to be more stable under high ionic strength conditions. The presence of CaCl2, however, even at low concentrations, induced the aggregation of DOM-coated Fe2O3NPs, mainly via charge neutralisation and bridging. This has significant implications in regards to the reactivity and fate of these materials in the environment.
Chon, K, Cho, J & Shon, H 2013, 'A pilot-scale hybrid municipal wastewater reclamation system using combined coagulation and disk filtration, ultrafiltration, and reverse osmosis: Removal of nutrients and micropollutants, and characterization of membrane foulants', Bioresource Technology, vol. 141, no. 1, pp. 109-116.View/Download from: Publisher's site
A pilot-scale municipal wastewater reclamation system using combined coagulation and disk filtration (CCDF), ultrafiltration (UF), and reverse osmosis (RO) membrane has been built to investigate removal of water contaminants and fouling mitigation. The reclaimed water using the pilot system could meet draft regulations on wastewater reuse of the California Department of Public Health (DOC: 0.5 mgC/L; TN: 5 mgN/L). The removal of micropolluants by the CCDF process and UF could not be evaluated by their MW, Log D, and charge characteristics. However, they were identified as governing factors affecting the removal of micropollutants by the RO. The CCDF process might effectively remove particulate materials capable of contributing to cake layer formation on the UF membrane surfaces but the residual coagulants provided a strong effect on fouling formation of the UF membrane. Thus, hydrophobic fractions of the desorbed UF membrane foulants were higher than those of the desorbed RO membrane foulants.
Chon, K, Cho, J & Shon, H 2013, 'Advanced characterization of algogenic organic matter, bacterial organic matter, humic acids and fulvic acids', Water Science And Technology, vol. 67, no. 10, pp. 2228-2235.View/Download from: Publisher's site
Advanced characterization techniques of organic matter, including bulk organic characterization, size-exclusion chromatography, three-dimensional excitation-emission matrix, Fourier transform infrared spectroscopy, and fractionations using Amberlite XAD-
Chon, K, Cho, J & Shon, H 2013, 'Fouling characteristics of a membrane bioreactor and nanofiltration hybrid system for municipal wastewater reclamation', Bioresource Technology, vol. 130, pp. 239-247.View/Download from: Publisher's site
A laboratory-scale membrane bioreactor (MBR) and nanofiltration (NF) hybrid system has been built to investigate effects of changes in characteristics of effluent organic matter by the MBR on fouling characteristics of the NF membranes. Large amounts of polysaccharide-like substances with small molecular weight and strong fluorescence intensity at the excitation wavelength of 230 nm and the emission wavelength of 420 nm were produced by microbial growth in the MBR. These substances had a great influence on fouling formation of the NF membranes. Fouling characteristics of the MBR were governed by both hydrophobic and hydrophilic fractions while hydrophilic fractions were found as major constituents of the desorbed NF membrane foulants. Flux decline rates of the NF membranes were closely associated with differences in their fouling layer compositions, meaning that performances of the NF membranes (i.e., flux decline) could be influenced by the membrane characteristics (i.e., surface zeta potential and contact angle).
El Saliby, I, Erdei, L, Kim, J & Shon, H 2013, 'Adsorption and photocatalytic degradation of methylene blue over hydro-genetitanate nanofibres produced by a peroxide method', Water Research, vol. 47, no. 12, pp. 4115-4125.View/Download from: Publisher's site
In this study, Degussa P25 TiO2 was partially dissolved in a mixture of hydrogen peroxide and sodium hydroxide at high pH. The fabrication of nanofibres proceeded by the hydrothermal treatment of the solution at 80 C. This was followed by acid wash in HCl at pH 2 for 60 min, which resulted in the formation of hydrogenetitanate nanofibres. The nanofibres were annealed at 550 C for 6 h to produce crystalline anatase nanofibres. The nanofibres were characterised for physico-chemical modifications and tested for the adsorption and photocatalytic degradation of methylene blue as a model water pollutant. An average specific surface area of 31.54 m2/g, average pore volume of 0.10 cm3/g and average pore size of 50 A were recorded. The nanofibres were effective adsorbents of the model pollutant and adsorbents and good photocatalysts under simulated solar light illumination. No reduction in photocatalytic activity was observed over three complete treatment cycles, and the effective separation of nanofibres was achieved by gravity settling resulting in low residual solution turbidity.
Fam, WA, Phuntsho, S, Shon, H & Lee, JH 2013, 'Performance comparison of thin-film composite forward osmosis membranes', Desalination and Water Treatment, vol. 51, no. 31-33, pp. 6274-6280.View/Download from: Publisher's site
Forward osmosis (FO) is an emerging low-energy technology. Much effort was given on developing a new membrane material and engineering membrane structure to improve the performance of FO membranes. The performances of two newly developed polyamide-based thin-film composite (TFC) FO membranes were tested and compared with the commercially available cellulose triacetate (CTA) FO membrane. The intrinsic properties of the two TFC FO membranes determined in RO experiments indicate superior performance of the membranes. When tested in FO experiments, TFC membranes delivered consistent results, confirming their outstanding permeability and selectivity properties. The study shows that future studies on membrane fouling will be necessary to have a better understanding of membrane performance and to further optimize membrane properties.
Kim, J, Phuntsho, S & Shon, H 2013, 'Pilot-scale nanofiltration system as post-treatment for fertilizer drawn forward osmosis desalination for direct fertigation', Desalination and Water Treatment, vol. 51, no. 31-33, pp. 6265-6273.View/Download from: Publisher's site
The integration of the fertilizer-drawn forward osmosis with nanofiltration (NF) has been investigated to evaluate the performance of NF process as a post-treatment. The primary objective of this study is to optimize the operating conditions such as feed flow rate and feed concentration, while producing fresh water including low nutrient (N) concentration can be directly used for irrigation. Investigation of operating parameters at the pilot-scale level focused on specific water flux and ammonium sulphate rejection. Results from this study showed that NF process applied as the post-treatment can effectively reject the N concentration more than 90%. Although other factors such as the applied pressure and the cross-flow rates played a certain role in the performance of the pilot-scale NF process, the influence of the feed concentration was more significant on the specific water flux and N rejection.
Kim, JB, Lee, KW, park, S, Shon, H, Shahid, M, El, SI, Lee, WE, kim, G & kim, J 2013, 'Preparation of Iron-Doped Titania from Flocculated Sludge with Iron-Titanium Composite Coagulant', Journal of Nanoscience & Nanotechnology, vol. 13, no. 6, pp. 4106-4109.View/Download from: Publisher's site
The main drawback of flocculation process with dye wastewater is the large amount of unrecyclable sludge which needs disposal. A novel process using Ti-salt flocculation to purify wastewater was developed to produced sludge that can be calcined to produce titania. In this study, irondoped TiO2 nanomaterial was successfully produced from sludge obtained by the flocculation of dye wastewater with a composite floculant including TiCl4 and FeSO4. The titania was characterised using scanning electron microscopy (SEM/EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), and the photodecomposition of acetaldehyde. The XDR results showed that the anatase and rutile structures were found after sludge calcination at 550 C and 640 C respectively. The elemental analyses were carried out using EDX. The rutile titania sample consisted of Ti (35.7 wt.%), Fe (14.7 wt.%), O (42.3 wt.%), P (2.6 wt.%) and Ca (4.7 wt.%). The photocatalytic activity was monitored for the photodecomposition of gas acetaldehyde. Iron-doped titania seems to play an important role in increasing the photocatalytic activity under UV light irradiation.
Kim, JB, Park, H-J, Lee, KW, Jo, AR, Kim, MW, Lee, YJ, Park, SM, Lee, KY, Shon, HK & Kim, J-H 2013, 'Application of Ti-salt Coagulant and Sludge Recycling for Phosphorus Removal in Biologically Treated Sewage Effluent', Korean Chemical Engineering Research, vol. 51, no. 2, pp. 257-262.View/Download from: Publisher's site
Phuntsho, S, Hong, S, Elimelech, M & Shon, H 2013, 'Forward osmosis desalination of brackish groundwater: Meeting waterq uality requirements for fertigation by integrating nanofiltration', Journal Of Membrane Science, vol. 436, no. 1, pp. 1-15.View/Download from: Publisher's site
The concept of fertiliser drawn forward osmosis (FDFO)desalination lies in the premise that fertilisers that serve as draw solutions (DS)add value to the FDFO product water for fertigation. However, because FDFO desalination is concentration based, the process can not continue beyond the concentration equilibrium, one of the major limitations of the forward osmosis (FO) process. This results in final FDFO product water that, unless subjected to substantial dilution with fresh water, exceeds the acceptable nutrient concentrations for direct fertigation. In this study, nanofiltration(NF has been assessed as an integrated process to FDFO desalination, either as a pre-treatment or post-treatment, to reduce the nutrient concentrations in the final product water and thereby allow direct use of the product water for fertigation with out further dilution. NFaspre-treatment or post-treatment was found effective in reducing the nutrient concentrations using brackish groundwater (BGW) sources with relatively low total dissolved solid (TDS). However, when using higher TDSBGW sources, the product water still required further dilution or post-treatment before fertigation. NF as post-treatment was found to be more advantageous both in terms of reduced nutrient concentrations in the final product water and energy consumption.
Phuntsho, S, Kim, J, Lotfi, F & Shon, H 2013, 'MONO/DI-ammonium phosphate fertilizers as draw solutions for forward osmosis desalination', IDA Journal of Desalination and Water Reuse, vol. 5, no. 1, pp. 34-39.
Forward osmosis (FO) can be suitably used to desalinate water for irrigation using fertilizer as draw agent due to the desalinated water containing diluted draw solution. Mono-ammonium hydrogen phosphate (MAP) and di-ammonium hydrogen phosphate (DAP) are the important group of the most concentrated soluble fertilizer materials containing both N and P, essential fertilizer elements needed by the plants. The comparative assessment of these two fertilizers as draw solution (DS) for FO desalination was conducted. The results indicate that both MAP and DAP can be used as a DS for FO desalination and for direct fertigation although concentration polarization significantly affected the water flux. MAP performed slightly better in terms of pure water flux. However, the performance ratio of DAP was comparable to MAP when saline feed water was used. Furthermore, DAP was seen as a better DS candidate for desalination and fertigation due to significantly lower reverse solute flux.
Phuntsho, S, Sahebi, S, Majeed, T, Lotfi, F, Kim, J & Shon, H 2013, 'Assessing the major factors affecting the performances of forward osmosis and its implications on the desalination process', Chemical Engineering Journal, vol. 231, pp. 484-496.View/Download from: Publisher's site
This study evaluates the influence of some of the major factors affecting the performances of forward osmosis (FO) desalination and assessed their potential implications on the overall process. The major factors assessed include membrane properties, draw solution (DS) properties, feed solution (FS) properties and the operating conditions. The influence of the membrane properties was evaluated using three types of membranes and in doing so we have also introduced one newly synthesized proprietary thin film composite FO (TFC-FO) membrane. The performances of TFC-FO membrane in terms of water flux and reverse solute flux were significantly higher than the commercial cellulose triacetate FO membrane and TFC reverse osmosis membrane in FO process. Although adequate osmotic pressure of DS is desirable for FO process, the influence of DS osmotic pressure was less significant at higher DS osmotic pressure and therefore selecting an optimum initial osmotic pressure is essential for FO process to minimize pumping energy. A critical DS concentration has been hypothesized to minimize the implications of DS concentrations on the capital and operational cost of the FO desalination plant. Total dissolved solids (TDS) of the FS play a significant role in the performance of FO process however the influence of feed TDS was less significant for feed higher than 20,000 mg/L indicating that FO has a promising potential for use with high TDS feed water. Although, water flux decreased, the reverse solute flux (RSF) and specific RSF also decreased slightly at higher feed TDS. For operating parameters, the influence of crossflow velocity and the crossflow direction was also investigated.
Zhao, Y, Gao, B, Qi, Q, Wang, Y, Phuntsho, S, Kim, JH, Yue, Q, Li, Q & Shon, H 2013, 'Cationic polyacrylamide as coagulant aid with titanium tetrachloride for low molecule organic matter removal', Journal of Hazardous Materials, vol. 258-259, no. 1, pp. 84-92.View/Download from: Publisher's site
This is the first attempt to use cationic polyacrylamide (PAM) as coagulant aid with titanium tetrachloride (TiCl4) to improve the coagulation performance and floc properties. Coagulation-flocculation treatment was applied to simulated water (with fulvic
Zhao, Y, Gao, B, Shon, H, Qi, Q, Phuntsho, S, Wang, Y, Yue, Q, Li, Q & Kim, J 2013, 'Characterization of coagulation behavior of titanium tetrachloride coagulant for high and low molecule weight natural organic matter removal: The effect of second dosing', Chemical Engineering Journal, vol. 228, no. 1, pp. 516-525.View/Download from: Publisher's site
A two-stage titanium tetrachloride (TiCl4) dosing strategy is applied for investigating the coagulation effect on simulated water containing humic acid (HA) and fulvic acid (FA) and these represent the dissolved organic matter (DOM). The influence of second TiCl4 dose on coagulation efficiency, flock re-growth and the fractal dimension properties is studied for the beneficial effect of the second coagulant dose. Moreover, the impact of increased shear on the ultra filtration permeate flux in coagulationultra filtration (CUF) hybrid process is explored. A small second dose essentially decreases the residual turbidity and improves the organic matter removal. Also, flocks with larger size and better recoverability result and having more compact structure than those obtained without the second TiCl4 coagulant dose. At the same total TiCl4 coagulant concentrations, the two-stage dosing mode reveals significant advantage over the single coagulant dosing in terms of turbidity removal, flock size and recoverability although organic matter removal and flock compactness degree are more or less deteriorated during the two-stage dosing process. The second TiCl4 dose contributes to larger re-generated flocks with better re-growth ability than those obtained without the second dose within a wide range of high shear rate and even with prolonged breaking period. Two-stage dosing mode could improve the ultra filtration permeate flux under certain shear conditions. An extension in breakage time leads to much severer flux decline than short breakage periods. In case of FA simulated water, the ultra filtration permeate flux was less sensitive to increasing shear rate than in case of HA simulated water.
Zhao, Y, Gao, B, Zhang, G, Phuntsho, S, Wang, Y, Yue, Q, Liu, Q & Shon, H 2013, 'Comparative study of floc characteristics with titanium tetrachloride against conventional coagulants: Effect of coagulant dose, solution pH, shear force and break-up period', Chemical Engineering Journal, vol. 233, pp. 70-79.View/Download from: Publisher's site
Characteristics of flocs formed by titanium tetrachloride (TiCl4), ferric chloride (FeCl3) and aluminum sulfate (Al2(SO4)3) were comparatively investigated in terms of floc growth rate, size, strength, recoverability and fractal dimension in real water treatment. Impacts of coagulant dose, solution pH and hydraulic conditions, including shear force and break-up period, on floc properties were investigated. Results showed that the floc size followed the order of TiCl4 > FeCl3 > Al2(SO4)3 within the dose range investigated. The response of floc strength to coagulant dose depended on the coagulant used, while the floc recoverability decreased with the increasing dose regardless of the coagulant used. Within the solution pH range investigated, the floc strength and recoverability showed the following order of Al2(SO4)3 > FeCl3 > TiCl4 and those of TiCl4 were the least affected by solution pH. Additionally, the floc strength decayed with the increasing shear force and break-up period for the three coagulants. TiCl4 yielded the flocs with the weakest recoverability within both the shear force and break-up period ranges investigated. Moreover, the floc compactness followed the order of FeCl3 > TiCl4 > Al2(SO4)3 under either shear force condition.
Zhao, Y, Phuntsho, S, Gao, B, Huang, X, Qi, QB, Wang, Y, Kim, JH, Shon, HK & Yue, QY 2013, 'Preparation and characterization of novel polytitanium tetrachloride coagulant for water purification', Environmental Science & Technology, vol. 47, no. 22, pp. 12966-12975.View/Download from: Publisher's site
Polymeric metal coagulants are increasingly being used to improve coagulation efficiency, yet the research on the development of titanium and particularly polytitanium salts remains limited. This study is the first attempt in the synthesis, characterization, and application of polytitanium salts as coagulants. Polytitanium tetrachloride (PTC) solutions with different basicity values B (OH/Ti molar ratio) were prepared using a slow alkaline titration method. Jar tests were conducted to assess coagulation performance using both synthetic and real raw water samples, and the floc characteristics were monitored online using a laser diffraction particle size analyzer. Electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) was utilized to identify various Ti species, with the results providing strong evidence of the presence of various hydrolyzed Ti species in the titanium aqueous phase. Compared to titanium tetrachloride (TiCl4), higher or comparable turbidity and organic matter removal efficiency could be achieved by PTC with improved floc characteristics in terms of size, growth rate, and structure. Besides, the water pH after PTC coagulation was significantly improved toward neutral pH. This study indicates that PTC is an effective and promising coagulant for water purification. Besides, the PTC flocculated sludge was able to recycle and produce functional TiO2 photocatalyst.
Jeong, S, Kim, S, Kim, CM, Vigneswaran, S, Nguyen, V, Shon, H, Kandasamy, JK & Kim, IS 2013, 'A detailed organic matter characterization of pretreated seawater using low-pressure microfiltration hybrid systems', Journal Of Membrane Science, vol. 428, pp. 290-300.View/Download from: Publisher's site
In this study, two different submerged membrane hybrid systems (SMHSs) namely (i) submerged membrane coagulation hybrid system (SMCHS) and (ii) submerged membrane coagulation-adsorption hybrid system (SMCAHS) were investigated as pretreatment options for seawater reverse osmosis. Organic matters in seawater before and after pretreatment were characterized in terms of XAD fractionation, molecular weight distribution (MWD) and fluorescence. A detailed study on the seawater organic matter (SWOM) structure was made through 1H-nuclear magnetic resonance (1H NMR), pyrolysis-gas chromatographyâmass spectrometry (Py-GC/MS) and liquid chromatography-mass spectrometry-ion trap-time of fright (LC/MS-IT-TOF). The seawater investigated in this study is mainly composed of hydrophilic matter (5773.2%). SMHSs removed a significant amount of organic matter. The EEM fluorescence showed a removal of humic-like materials by SMHSs. In addition, humic-like materials relative to protein-like compounds were reduced significantly but the aromaticity of humic-like materials increased. After pretreatment by SMHSs, humics and biopolymers of over 900 Da. were found to be reduced and their structure associated with element composition was also changed. The transformation of the SWOM structure after SMHSs pretreatment may have been due to hydrolyzation or oxidization of the organic compounds such as humics and biopolymers resulting in poly-conjugation to aromatic compounds. SMHSs were effective in improving the RO performance leading to higher RO permeate flux and lower permeate flux decline. The pretreatment reduced the amount of foulants on the RO membrane.
Jeong, S, Okour, Y, Nguyen, T, Shon, H & Vigneswaran, S 2013, 'Ti-salt flocculation for dissolved organic matter removal in seawater', Desalination and Water Treatment, vol. 51, no. 16-18, pp. 3591-3596.View/Download from: Publisher's site
In this study, the removal of different fractions of organic matter in seawater was investigated using titanium tetrachloride (TiCl4) flocculation and compared with ferric chloride (FeCl3) flocculation. The organic matter fractions were characterised using liquid chromatographyorganic carbon detector (LCOCD). Results showed the hydrophobic compounds removal was dominant by both flocculants. However, the removal of hydrophilic organic compounds, such as humics and low-molecular weight neutral compounds of seawater, was superior by TiCl4 flocculation compared to FeCl3 flocculation and this removal increased considerably with the increase of TiCl4 doses. The flocculated sludge after TiCl4 flocculation was incinerated to produce titanium dioxide (TiO2) nanoparticle. TiO2 from seawater sludge characterised by X-ray diffraction (XRD) and scanning electron microscope/energy-dispersive X-ray spectroscopy (SEM/EDS) showed predominant anatase phase with Si as a main dopant.
Kus, BG, Kandasamy, JK, Vigneswaran, S, Shon, H & Moody, G 2013, 'Gravity driven membrane filtration system to improve the water quality in rainwater tanks', Water Science & Technology: Water Supply, vol. 13, no. 2, pp. 479-485.View/Download from: Publisher's site
The characterisation of rainwater in metropolitan Sydney and in rural New South Wales was undertaken. The results showed that factors such as the lack of vehicular traffic, air pollution and urban contamination meant that rural rainwater water quality was better. The rain water collected in both metropolitan and rural areas generally complied with the 2004 Australian Drinking Water Guidelines except for parameters such as the pH in both the metropolitan and rural rainwater tanks and the turbidity, and lead levels from the metropolitan tanks. This paper also reports the results of a laboratory and a pilot scale study with a deep bed filter (granular activated carbon, GAC) and microfiltration (MF) hollow fibre membrane filter system used to treat raw rainwater collected from a metropolitan rainwater tank. The results of the laboratory experiment and pilot scale systems focus on the non-compliant parameters of the sampling program, i.e. turbidity, lead and dissolved organic carbon (DOC). It was found that rainwater treated by the GAC filter removed the majority of the turbidity and organic substances. The treatment system reduced the concentration of turbidity, lead and DOC to below the Australian Drinking Water Guidelines limits. The pilot plant experiment demonstrated that a GAC filter system and gravity driven membrane could result in low cost and low maintenance operation.
Kus, BG, Kandasamy, JK, Vigneswaran, S, Shon, H & Moody, G 2013, 'Household rainwater harvesting system - Pilot scale gravity driven membrane-based filtration system', Water Science & Technology: Water Supply, vol. 13, no. 3, pp. 790-797.View/Download from: Publisher's site
This paper presents the results of a pilot scale study consisting of pre-treatment with a granular activated carbon (GAC) filter followed by membrane filtration. Detailed characterisation of rainwater tanks has highlighted that turbidity, dissolved organic carbon (DOC) and heavy metals, in particular lead, were not compliant with the 2004 Australian Drinking Water Guidelines (ADWG). Further, organic matter present in the water causes membrane fouling and leads to carcinogenic compounds upon chlorination. A GAC filter was used as a first step to remove dissolved organic matter (measured in terms of DOC) in particular and also to reduce the concentration, of turbidity and lead. Membrane filtration can remove any remaining solids reducing the concentrations of turbidity and microorganisms. In this study a pilot scale rainwater treatment system consisting of a gravity fed GAC filter and membrane filter (Ultra Flo) was operated for a period of 120 days. The performance of this system was assessed in terms of membrane flux and improvement in water quality measured against the 2004 Australian Drinking Water Guidelines. Determination of the flux especially in the later stages of membrane operation was important to be able to size the filters in a manner that meets the expected demand. The treatment system of GAC filter and membrane filter was effective in reducing the turbidity, DOC and heavy metals. The system reduced the turbidity to levels of 0.30.4 NTU, below the ADWG limit of 1 NTU.
Shon, H, Phuntsho, S, Chaudhary, DS, Vigneswaran, S & Cho, J 2013, 'Nanofiltration for water and wastewater treatment - a mini review', Drinking Water Engineering and Science, vol. 6, no. 1, pp. 47-53.View/Download from: Publisher's site
The application of membrane technology in water and wastewater treatment is increasing due to stringent water quality standards. Nanofiltration (NF) is one of the widely used membrane processes for water and wastewater treatment in addition to other applications such as desalination. NF has replaced reverse osmosis (RO) membranes in many applications due to lower energy consumption and higher flux rates. This paper briefly reviews the application of NF for water and wastewater treatment including fundamentals, mechanisms, fouling challenges and their controls.
Chekli, L, Phuntsho, S, Kandasamy, J & Shon, H 2013, 'Assessing the aggregation behaviour of iron oxide nanoparticles by using a multi-method approach.', Technical Proceedings of the 2013 NSTI Nanotechnology Conference and Expo, NSTI-Nanotech 2013, vol. 1, pp. 47-50.
Iron nanoparticles are becoming increasingly popular for the treatment of contaminated soil and groundwater; however, their mobility and reactivity in subsurface environments are significantly affected by their tendency to aggregate. Assessing their stability under environmental conditions is crucial for determining their environmental fate. A multi-method approach (including different size-measurement techniques) was used to thoroughly characterise the behaviour of iron oxide nanoparticles (Fe2O3NPs) under environmentally relevant conditions. Although recent studies have demonstrated the importance of using a multi-method approach when characterising nanoparticles, the majority of current studies continue to use a single-method approach. Discussions and examples to support the need of a multi-method approach to characterise the aggregation of nanoparticles will be presented in this study.
Chon, K, Cho, J, Shon, H & Chon, K 2012, 'Advanced characterization of organic foulants of ultrafiltration and reverse osmosis from water reclamation', Desalination, vol. 301, pp. 59-66.View/Download from: Publisher's site
Organic foulants obtained from ultrafiltration (UF) and reverse osmosis (RO) membranes of a large scale municipal water reclamation plant were rigorously characterized using conventional and advanced characterization analyses (e.g. pyrolysis and mass spectrometry) in order to identify major constituents of the organic foulants and investigate fouling characteristics in a large scale application of the UF and RO membranes. Although water qualities and characteristics of effluent organic matter in the feed water were slightly changed during the UF membrane, fouling characteristics of the UF and RO membranes used in a large scale municipal water reclamation plant were significantly different according to the type of membranes. Hydrophobic fractions comprising of carboxylic acids and aldehydes strongly contributed to the fouling formation of the UF membrane compared to that of the RO membranes whereas the RO membrane foulants mainly consisted of hydrophilic fractions comprising of amides and alcohols due to the repulsive electrostatic interaction between negatively charged RO membrane surfaces and hydrophobic fractions with a negative charge, indicating that the membrane characteristics could play an important role in the fouling formation of the tested UF and RO membranes.
Chon, K, Shon, H & Cho, J 2012, 'Membrane Bioreactor And Nanofiltration Hybrid System For Reclamation Of Municipal Wastewater: Removal Of Nutrients, Organic Matter And Micropollutants', Bioresource Technology, vol. 122, pp. 181-188.View/Download from: Publisher's site
A membrane bioreactor (MBR) and nanofiltration (NF) hybrid system was investigated to demonstrate the performance of treating nitrogen, phosphorus and pharmaceuticals and personal care products (PPCPs) in municipal wastewater. With the MBR and NF (molecular weight cut off (MWCO): 210 Da), the concentration of total nitrogen (TN) and total phosphorus (TP) was effectively reduced by nitrification by MBR and negatively charged surface of NF (TN: 8.67 mgN/L and TP: 0.46 mgP/L). Biosorption and microbial decomposition in MBR seem to be major removal mechanisms for the removal of PPCPs. Among various parameters affecting the removal of PPCPs by NF, namely, physicochemical properties of the PPCPs (charge characteristics, hydrophobicity and MW) and membranes (MWCO and surface charge), the MWCO effect was found to be the most critical aspect.
Kim, C, Lee, S, Shon, H, Elimelech, M & Hong, S 2012, 'Boron transport in forward osmosis: Measurements, mechanisms, and comparison with reverse osmosis', Journal Of Membrane Science, vol. 419-420, pp. 42-48.View/Download from: Publisher's site
The physical and chemical factors affecting boron solute flux behavior and membrane transport mechanisms in forward osmosis (FO) have been systematically investigated. Boron solute flux behavior in FO was further compared with that in reverse osmosis (RO) by employing identical plate-and-frame cells and membranes under the same filtration conditions. The influence of draw solution pH, draw solution type, and membrane orientation on boron solute flux was examined for FO, and the effects of water flux, cross-flow velocity, feed water boron concentration, and solution pH on boron solute flux were examined for both FO and RO. Results show that reverse salt diffusion, a unique feature of FO, is a key mechanism governing boron solute flux in FO. Boron solute flux through the FO membrane was inversely proportional to the degree of reverse salt diffusion by draw solution. The higher boron rejection observed in FO compared to RO is also attributed to reverse salt diffusion in FO. It is also shown that membrane orientation in FO plays an important role, affecting boron solute flux due to different degrees of internal concentration polarization. In both FO and RO, boron solute flux increased with increasing water flux. However, the influence of water flux on boron solute flux was less significant in FO than RO. Furthermore, boron solute flux decreased with increasing feed water pH due to the conversion of the neutral boric acid to borate anions. The findings provide new insight in to the mechanisms and factors controlling boron solute transport in FO.
Sharma, G, Shon, H & Phuntsho, S 2012, 'Electrocoagulation And Crossflow Microfiltration Hybrid System: Fouling Investigation', Desalination and Water Treatment, vol. 43, no. 1-3, pp. 253-259.View/Download from: Publisher's site
The fouling study of crossflow microfiltration (MF) was comparatively studied with feedwater containing kaolin suspension with and without electrocoagulation (EC) pre-treatment. An acrylonitrile butadiene styrene (ABS) MF membrane of pore size 0.4 lm was used in this study. The experiments were carried out at three different concentration of kaolin (100, 400 and 800 mg/l) and with three different crossflow velocities of 0.5, 1 and 1.5 l/min. When the feedwater was pre-treated by EC, the fouling was found to follow standard law of filtration. Besides the standard filtration law, the fouling mechanism also followed the classical cake filtration model due to formation of a secondary membrane.
Zhao, Y, Gao, B, Shon, H, Wang, Y, Kim, JH, Yue, Q & Bo, XY 2012, 'Anionic polymer compound bioflocculant as a coagulant aid with aluminum sulfate and titanium tetrachloride', Bioresource Technology, vol. 108, pp. 45-54.View/Download from: Publisher's site
The objectives of this study are to investigate the impacts of anionic polymer compound bioflocculant (CBF) as a coagulant aid on coagulation performance and floc characteristics with titanium tetrachloride (TiCl4) and aluminum sulfate (Al2(SO4)3). The effect of dosing sequence was also investigated. Floc size, breakage, regrowth and floc fractal dimension were examined using a laser diffraction instrument. The results showed that CBF with TiCl4 or Al2(SO4)3 coagulants exhibited synergistic effects by promoting dissolved organic carbon (DOC) removal. For both TiCl4 and Al2(SO4)3, the floc recoverability was improved by CBF addition, and the flocs formed by TiCl4 and the corresponding dual-coagulants showed weaker recovery ability than those by Al2(SO4)3 and the corresponding dual-coagulants. Fractal dimension analysis demonstrated that the floc fractal dimension values increased with the increasing coagulant dose. The effect of CBF on fractal dimension of the flocs generated by TiCl4 was different from that of Al2(SO4)3.
Zhao, Y, Gao, B, Wang, Y, Shon, H, Bo, XY & Yue, Q 2012, 'Coagulation performance and floc characteristics with polyaluminum chloride using sodium alginate as coagulant aid: A preliminary assessment', Chemical Engineering Journal, vol. 183, pp. 387-394.View/Download from: Publisher's site
The effect of sodium alginate (SA) on coagulation performance and floc characteristics with polyaluminum chloride (PAC) was evaluated in synthetic humic acid-kaolin water treatment. Coagulation performance and floc characteristics of PAC were investigated for comparison. The results showed that PAC plus SA exhibited certain synergistic effect on DOC (dissolved organic carbon) and turbidity removal. DOC removal was more enhanced by SA at low PAC doses than at higher ones, while turbidity removal was enhanced when PAC doses were larger than 1.5 mg/L. The growth, breakage, regrowth and fractal nature of flocs were investigated using Mastersizer 2000, with the results suggesting that the aggregated flocs after PAC-SA (PAC dosed first) flocculation showed faster growth rate and with larger floc size compared with the flocs formed by PAC. Besides, PAC-SA gave the flocs with more open structure but better recovery ability after floc breakage compared with PAC.
Zhao, Y, Wang, Y, Gao, B, Shon, H, Kim, J & Yue, Q 2012, 'Coagulation performance evaluation of sodium alginate used as coagulant aid with aluminum sulfate, iron chloride and titanium tetrachloride', Desalination, vol. 299, no. 1, pp. 79-88.View/Download from: Publisher's site
Coagulation-flocculation was applied to humic acid-kaolin synthetic water samples, using sodium alginate (SA) as a coagulant aid with primary coagulants used: aluminum sulfate (Al2(SO4)3), iron chloride (FeCl3) and titanium tetrachloride (TiCl4). The corresponding dual-coagulants were dented as Al2(SO4)3-SA, FeCl3-SA and TiCl4-SA by dosing SA 30 s after primary coagulants addition. Coagulation performance was investigated in terms of turbidity reduction and dissolved organic carbon (DOC) removal and the flocs were characterized in terms of size, growth rate, strength, recoverability and structure through onâline monitoring of the coagulation process using Mastersizer 2000. The results showed that dual-coagulants could remove HA effectively with appropriate SA doses. Primary coagulants plus SA exhibited an apparent improvement in both floc growth rate and floc size. Besides, floc recoverability was significantly increased. It was suspected that SA addition may have a positive effect on the solid/liquid separation process. However, dual-coagulants gave the flocs with more open structure.
Chekli, L, Phuntsho, S, Shon, H, Vigneswaran, S, Kandasamy, JK & Chanan, AP 2012, 'A Review Of Draw Solutes In Forward Osmosis Process And Their Use In Modern Applications', Desalination and Water Treatment, vol. 43, no. 1-3, pp. 167-184.View/Download from: Publisher's site
Forward osmosis (FO) is one of the emerging membrane technologies which has gained renewed interest recently as a low energy desalination process. The central to FO process is the draw solution (DS) and the membrane because both play a substantial role o
Heran, M, Aryal, R, Shon, H, Vigneswaran, S, Elmaleh, S & Grasmick, A 2012, 'How To Optimize Hollow-Fiber Submerged Membrane Bioreactors', Water Environment Research, vol. 84, no. 2, pp. 115-119.View/Download from: Publisher's site
Membrane fouling is linked to reversible or irreversible accumulation of macromolecules and solids on membrane surfaces and to the irreversible adsorption inside pores. If reversible accumulation can be controlled by filtering in subcritical conditions, then adsorption could also be minimized by reducing the soluble organic matter [extracellular polymeric substances, soluble microbial products (SMP)]. This research shows how the choice of operating parameters related to biological reaction (solid retention time and the organic loading rate) can influence the process rate and the by-product (SMP) production. It also illustrates how suspension characteristics and membrane aeration can influence membrane fouling control according to the hollow fiber configuration and to the different scales of observation. The investigations were based on the definition of different fouling level and fine-tuning of a model to better understand the effects of operating parameters on membrane bioreactor filtration.
Jeong, S, Nguyen, V, Shon, H & Vigneswaran, S 2012, 'The Performance Of Contact Flocculation-Filtration As Pretreatment Of Seawater Reverse Osmosis', Desalination and Water Treatment, vol. 43, no. 1-3, pp. 246-252.View/Download from: Publisher's site
Deep bed filtration has traditionally been used as a pretreatment in seawater desalination. The performance of contact flocculationâfiltration (CFF) as pretreatment of seawater reverse osmosis (SWRO) was evaluated in terms of pressure drop through the filter and removal of organics and turbidity. The average turbidity, total suspended solids, and dissolved organic carbon (DOC) of raw seawater were 0.92 NTU, 3.6, and 1.12mg/L, respectively. The performances of CFF were experimentally evaluated with different flocculant doses (0.5â3.0mg Fe3+/L) and rapid mixing times (1.7â14.4 s). Here rapid mixing was performed in a spiral flocculation unit which consisted of a PVC tube of length 0.5m and internal diameters of 0.16 and 0.40 cm. The experimental results show that the filtration rate of 10.0m/h led to an extensive increase in both head loss (pressure drop) and turbidity as compared to those at filtration rates of 5.0 and 7.5 m/h. The head loss also significantly decreased when the flocculant dose was reduced from 3 to 0.5mg Fe3+/L. However, the organic matter (26% of DOC) removal was lower at a lower dose of ferric chloride (1.0 mg/L as Fe3+). The removal efficiency of DOC at low concentration of ferric was improved considerably through the improvement of rapid mixing. The application of CFF process also led to a significant decrease in ultrafiltermodified fouling index (UF-MFI).
Kus, BG, Johir, MH, Kandasamy, JK, Vigneswaran, S, Shon, H, Sleigh, R & Moody, G 2012, 'Performance Of Granular Medium Filtration And Membrane Filtration In Treating Stormwater For Harvesting And Reuse', Desalination and Water Treatment, vol. 45, no. 1-3, pp. 120-127.View/Download from: Publisher's site
This paper discusses laboratory scale and pilot scale treatment systems used to in treat water from a stormwater canal in Carlton, Sydney. The laboratory scale pre-treatment systems investigated included flocculation, GAC filtration and fibre filter prior to laboratory scale steriflow stainless steel membrane filter. The results showed that these pre-treatments improved the quality of the filtrate as measured by the turbidity and TOC removal effi ciency. The use of pre-treatment improved the TOC removal efficiency from 10% to 90%. Among the three pretreatment methods, GAC filter resulted in the highest TOC removal efficiency (88%). Pilot scale experiments were also carried out using stainless steel membrane filtration and GAC filtration at Carlton, Sydney. Pilot scale experiments showed that the Steri-Flow membrane filter treatment without any pre-treatment achieved an effluent fi ltrate turbidity of between 0.79â0.99 NTU which were well below the 5 NTU ADWG (2004) limit . The influent raw stormwater had generally low concentrations of heavy metals. Following membrane filtration the concentration of all heavy metals were reduced to very low levels and well within the ADWG (2004)  limits. The membrane fi lter could not remove TOC in significant amounts. GAC adsorption used as post-treatment following Steri-flow membrane treatment effectively reduced the TOC influent feed levels. GAC filtration of stormwater provided a 70% removal of organics. It removed all types of organic. The GAC filter did not provide any further improvement to the turbidity level or heavy metal concentration following treatment with the Steri-flow membrane system.
Kus, BG, Kandasamy, JK, Vigneswaran, S, Shon, H & Moody, G 2012, 'Two Stage Filtration For Stormwater Treatment: A Pilot Scale Study', Desalination and Water Treatment, vol. 45, no. 1-3, pp. 361-369.View/Download from: Publisher's site
This paper presents the results of the granular medium filter and membrane (Ultra Flo membrane) filter experiments conducted with raw stormwater collected from a stormwater canal at Carlton, in Sydney. The filter medium experimented were granular activat
Phuntsho, S, Shon, H, Hong, S, Lee, S, Vigneswaran, S & Kandasamy, JK 2012, 'Fertiliser drawn forward osmosis desalination: the concept, performance and limitations for fertigation', Reviews in Environmental Science and Biotechnology, vol. 11, no. 2, pp. 147-168.View/Download from: Publisher's site
With the world's population growing rapidly, pressure is increasing on the limited fresh water resources. Membrane technology could play a vital role in solving the water scarcity issues through alternative sources such as saline water sources and wastewater reclamation. The current generation of membrane technologies, particularly reverse osmosis (RO), has significantly improved in performance. However, RO desalination is still energy intensive and any effort to improve energy efficiency increases total cost of the product water. Since energy, environment and climate change issues are all inter-related, desalination for large-scale irrigation requires new novel technologies that address the energy issues. Forward osmosis (FO) is an emerging membrane technology. However, FO desalination for potable water is still a challenge because, recovery and regeneration of draw solutes require additional processes and energy. This article focuses on the application of FO desalination for non-potable irrigation where maximum water is required. In this concept of fertiliser drawn FO (FDFO) desalination, fertilisers are used as draw solutions (DS). The diluted draw solution after desalination can be directly applied for fertigation without the need for recovery and regeneration of DS. FDFO desalination can make irrigation water available at comparatively lower energy than the current desalination technologies. As a low energy technology, FDFO can be easily powered by renewable energy sources and therefore suitable for inland and remote applications. This article outlines the concept of FDFO desalination and critically evaluates the scope and limitations of this technology for fertigation, including suggestions on options to overcome some of these limitations
Phuntsho, S, Shon, H, Majeed, T, El Saliby, I, Vigneswaran, S, Kandasamy, JK, Hong, S & Lee, S 2012, 'Blended Fertilizers as Draw Solutions for Fertilizer-Drawn Forward Osmosis Desalination', Environmental Science & Technology, vol. 46, pp. 4567-4575.View/Download from: Publisher's site
In fertilizer-drawn forward osmosis (FDFO) desalination, the final nutrient concentration (nitrogen, phosphorus, potassium (NPK)) in the product water is essential for direct fertigation and to avoid over fertilization. Our study with 11 selected fertilizers indicate that blending of two or more single fertilizers as draw solution (DS) can achieve significantly lower nutrient concentration in the FDFO product water rather than using single fertilizer alone. For example, blending KCl and NH4H2PO4 as DS can result in 0.61/1.35/1.70 g/L of N/P/K, which is comparatively lower than using them individually as DS. The nutrient composition and concentration in the final FDFO product water can also be adjusted by selecting low nutrient fertilizers containing complementary nutrients and in different ratios to produce prescription mixtures. However, blending fertilizers generally resulted in slightly reduced bulk osmotic pressure and water flux in comparison to the sum of the osmotic pressures and water fluxes of the two individual DSs as used alone. The performance ratio or PR (ratio of actual water flux to theoretical water flux) of blended fertilizer DS was observed to be between the PR of the two fertilizer solutions tested individually. In some cases, such as urea, blending also resulted in significant reduction in N nutrient loss by reverse diffusion in presence of other fertilizer species.
Phuntsho, S, Vigneswaran, S, Kandasamy, JK, Hong, S, Lee, S & Shon, H 2012, 'Influence of temperature and temperature difference in the performance of forward osmosis desalination process', Journal Of Membrane Science, vol. 415-416, pp. 734-744.View/Download from: Publisher's site
Forward osmosis (FO) is an emerging technology for low energy desalination. Amongst the many other factors, emperature of the draw solution (DS) and feed solution (FS) plays an important role in influencing the performance of the FO process. In this study, the influence of the temperature and the temperature difference on the performance of FO process has been studied in terms of water and solute fluxes. Temperature difference was maintained by elevating only one of the solutions (eitherDSorFS). The results indicate that, water flux on average increases by up to 1.2 % for every degree rise in temperature from 25Â°C to 35Â°C while this rise is 2.3% from 25Â°C to 45Â°C. Providing a temperature difference by elevating only the DS also enhanced the water flux significantly, although it was lower than FO process operated at isothermal conditions. However, elevating only the temperature of FS did not significantly improve the water flux although it was higher than the FO process operated at 25Â°C. This as significant implications in FO process because the total mass of the DS requiring heat energy is significantly less than the total FS used. The influences of temperature in the FO process such as through changes in the thermodynamic properties of the solutions and the various concentration polarisation effects are also explained in details.
Shon, HK, Nghiem, LD, Kim, S, Shu, L & Jegatheesan, JV 2012, 'Challenges in Environmental Science and Engineering, CESE-2011: 25-30 September, Ever Green Plaza Hotel, Tainan City, Taiwan Preface', DESALINATION AND WATER TREATMENT, vol. 47, no. 1-3, pp. 1-2.View/Download from: Publisher's site
El Saliby, I, Okour, Y, Shon, H, Kandasamy, JK, Lee, WE & Kim, J 2012, 'TiO2 nanoparticles and nanofibres from TiCl4 flocculated sludge: Characterisation and photocatalytic activity', Journal of Industrial and Engineering Chemistry, vol. 18, no. 3, pp. 1033-1038.View/Download from: Publisher's site
In this study, dye and secondary effluent wastewaters were used to generate a non-hazardous sludge. Anatase TiO2 nanoparticles have been successfully synthesised from the calcination of the TiCl4 flocculated sludge. A conventional hydrothermal method was adopted to produce anatase nanofibres (calcined at 600 8C) from TiO2 nanoparticles. X-ray diffraction, scanning electron microscopy and transmission electron microscopy investigations showed the highly crystalline nanoparticles and nanofibres after calcination. The size of nanofibres was related to the size of their nanoparticles precursors. Nanoparticles had larger surface area than nanofibres, lower pore volume and bigger pore diameter. Energy dispersive X-ray analysis revealed that impurities can be successfully removed by a subsequent hydrothermal/acid wash of nanoparticles. Nanoparticles had better overall photocatalytic activity for the degradation of organics in synthetic wastewater compared to nanofibres. On the other hand, nanofibres had a better adsorption capacity.
El Saliby, I, Shahid, M, McDonagh, AM, Shon, H & Kim, J 2012, 'Photodesorption of organic matter from titanium dioxide particles in aqueous media', Journal of Industrial and Engineering Chemistry, vol. 18, pp. 1774-1780.View/Download from: Publisher's site
Photo-induced desorption of organic compounds from TiO2 particles in aqueous media during photocatalysis has promising applications in water treatment. Photodesorption is a relatively fast phenomenon that facilitates the regeneration of photocatalysts with low energy consumption while concentrating the waste products in an energy and water efficient process. We propose that this transport phenomenon involves a significantly reduced affinity between the photocatalyst and pollutants upon UV illumination, and leads to the rapid detachment/decomposition of adsorbed pollutants. In this study, we report the effect of experimental conditions (pH, photocatalyst loading, organic loading, UV light irradiation and flow rate) on this phenomenon in a recirculating photocatalysis continuous reactor. Initially, organic compounds were allowed to adsorb on the surface of the photocatalyst (Degussa P25) until adsorption equilibrium was achieved. The photodesorption phenomenon was observed shortly after UVlight illumination of TiO2 but before the bulk photocatalytic oxidation takes place. The pH of the solution was found to affect both the adsorption and the desorption percentages revealing the role of particle charge on this phenomenon. Additionally, a 1 g/L loading of photocatalyst showed an optimum photodesorption rate using a single strength synthetic wastewater at pH 7.
Chang, Y, Tanong, K, Xu, J & Shon, H 2011, 'Microbial community analysis of an aerobic nitrifying-denitrifying MBR treating ABS resin wastewater', Bioresource Technology, vol. 102, no. 12, pp. 5337-5344.View/Download from: Publisher's site
A two-stage aerobic membrane bioreactor (MBR) system for treating acrylonitrile butadiene styrene (ABS) resin wastewater was carried out in this study to evaluate the system performance on nitrification. The results showed that nitrification of the aerobic MBR system was significant and the highest TKN removal of approximately 90% was obtained at hydraulic retention time (HRT) 18 h. In addition, the result of nitrogen mass balance revealed that the percentage of TN removal due to denitrification was in the range of 8.7â19.8%. Microbial community analysis based on 16s rDNA molecular approach indicated that the dominant ammonia oxidizing bacteria (AOB) group in the system was a b-class ammonia oxidizer which was identified as uncultured sludge bacterium (AF234732). A heterotrophic aerobic denitrifier identified as Thauera mechernichensis was found in the system. The results indicated that a sole aerobic MBR system for simultaneous removals of carbon and nitrogen can be designed and operated for neglect with an anaerobic unit.
El Saliby, I, Erdei, L, Shon, H & Kim, J 2011, 'Development of visible light sensitive titania photocatalysts by combined nitrogen and silver doping', Journal of Industrial and Engineering Chemistry, vol. 17, no. 2, pp. 358-363.View/Download from: Publisher's site
In this study we present the effects of non-metal (nitrogen) and metal/non-metal (silver/nitrogen) dopants on titanium dioxide (TiO2) in synthesising visible-light reactive photocatalysts. Nanopowders of TiO2-N and TiO2-NâAg were synthesised using a simple procedure at room temperature. For nitrogen doping, a dispersion of Degussa P-25 was treated with ammonium hydroxide. The obtained modified catalyst was further treated with silver nitrate powder to facilitate silver-nitrogen co-doping. The produced catalysts were characterised using X-ray diffraction, X-ray photoelectron spectroscopy, and specific surface area measurements. Scanning electron microscopy/energy dispersive X-ray and transmission electron microscopy were adapted to detect changes in the morphology and in the chemical composition of synthesised catalysts. The results show that both the morphology and appearance of catalysts were modified to yield nanopowders of yellowish color and relatively high specific surface area. Methylene blue (MB) dye was used as a model aquatic contaminant in 23 mg/L concentration to study the performance of these novel photocatalysts in an aerobic mixed batch reactor system under white light irradiation. Both nitrogen and nitrogen-silver co-doping lead to visible light sensitivity and the new catalysts showed remarkable activities in the decolorisation of MB.
El Saliby, I, Erdei, L, Shon, H, Kim, JB & Kim, J 2011, 'Preparation and characterisation of mesoporous photoactive Na-titanate microspheres', Catalysis Today, vol. 164, no. 1, pp. 370-376.View/Download from: Publisher's site
Mesoporous Na-titanate microspheres were fabricated by a simple low temperature hydrothermal synthesis. Microsphereswereobtained after treating TiO2 (Degussa P-25) with a mixture of sodium hydroxide (NaOH) and hydrogen peroxide (H2O2) at 25â¦C and 80 â¦C. The as-prepared powders were characterised by X-ray diffraction, N2 adsorptionâdesorption measurements and scanning electron microscope/energy dispersive X-ray spectroscopy. The as-prepared microspheres were calcined at 550 â¦C to investigate the effect of calcination on morphology and characteristics. Microspheres were tested for the adsorption and photodecomposition of methylene blue (MB) under ultraviolet light. The results revealed that microspheres with average diameter of 700nmwere formed by self-assembly of tiny TiO2 nanoparticles during the reaction at 25 â¦C, whereas spherical aggregation of nanofibres was detected in powders produced at 80 â¦C. Calcination of samples had low impact on morphology, adsorption and photocatalytic degradation of MB. These novel materials are effective adsorbents of MB, and also capable of its photodecolorisation.
Kim, D, Shon, H, Sharma, G & Cho, J 2011, 'Charge effect of natural organic matter for ultrafiltration and nanofiltration membranes', Journal of Industrial and Engineering Chemistry, vol. 17, no. 1, pp. 109-113.View/Download from: Publisher's site
Natural organic matter (NOM) is one of the major membrane foulant during the ultrafiltration (UF) and nanofiltration (NF) processes of water and wastewater treatment. The purpose of this study is to determine the effect of membrane and NOM charge on NOM removal efficiency and membrane fouling. Fractions of NOM including colloidal organic matter (COM), hydrophobic NOM (HP-NOM) and transphillic NOM (TL-NOM) were isolated from Nakdong river in Korea and filtered through UF and NF membranes under various pH conditions to control membrane and NOM charge using the bench-scale cross-flow filtration unit. Each NOM fraction has a different size and functionality. Each UF and NF charge affected NOM removal and membrane fouling. Membrane charge of UF affected both membrane fouling and NOM removal of charged NOM and non-charged NOM. However, membrane charge of NF affected both membrane fouling and NOM removal efficiency of charged NOM while it was not influenced by that of non-charged NOM.
Kim, J, Cho, DL, Kim, G, Gao, B & Shon, H 2011, 'Titania Nanomaterials Produced from Ti-Salt Flocculated Sludge in Water Treatment', Catalysis Surveys from Asia, vol. 15, no. 2, pp. 117-126.View/Download from: Publisher's site
Titania is the most widely used metal oxide for the applications of pigments, paper, solar cells and environmental purification. In order to meet the demand of a large amount of titania, our group has developed a novel process which could significantly lower the cost of waste disposal in water treatment, protect the environment and public health and yield economically valuable titania. Titanium tetrachloride (TiCl4) or titanium sulfate (Ti(SO4)2) as an alternative coagulant in water treatment has been explored for the removal of various pollutants from contaminated water or wastewater. Flocculation efficiencies of the Ti-salts were superior to those of Al- and Fe- salts with additional benefits in that a large amount of titania can be produced by calcinating the flocculated floc. The produced titania showed high photocatalytic activity for the removal of volatile organic compounds. The large amount of titania can be applied to pigments, environment and construction materials which require a lot of titania usages. This review paper presents an historical progress from fundamental to application in terms of the detailed production process, characterization, photoactivity of titania produced from Ti-salt flocculated sludge, and its various applications.
Kim, J, Okour, Y, Yang, H, Kim, JB & Shon, H 2011, 'Preparation and Characterisation of TiO2 Nanoparticle and Titanate Nanotube Obtained from Ti-Salt Flocculated Sludge with Drinking Water and Seawater', Journal of Nanoscience & Nanotechnology, vol. 11, no. 2, pp. 1640-1643.View/Download from: Publisher's site
This study aimed to prepare and characterise titanium dioxide (TiO2) nanopartictes and lilanate nanolubes produced from Ti-sat flocculated sludge with drinking water (DW) and seawater (SW). The Ti-salt flocculated sludge from DW and SW was incinerated at 600 Â°C to produce TiO2 nanoparticles. XRD results showed that the anatase TiO2 structure was predominant for TiO2 from DW (TiO2-DW) and TiO2 from SW (TiO2-SW), which were mainly doped with carbon atoms. Titanate nanotubes (tiNT) were obtained when TiO2-DW and TiO2-SW were hydrothermally treated wilh NaOH solution. Structure phase, shape, crystalisation and photocatalylic activity of tiNT were affected by the incineration temperature and the amount of sodium present in different tiNT. The tiNT doped with thiourea incinerated at 600 Â°C presented anatase phase, showing a high increase of the degree of crystallisation with nanotube-like structures. The photocatalylic activity of these photocatalysts was evaluated using photooxldation of gaseous acetaldehyde. Thiourea doped tiNT-DW and tiNT-SW showed similar photocatalytic activity compared to commercially available TiO2-P25 under UV light and indicated a photocatalytic activity under visible light.
Lee, S, Kim, K, Shon, H, Kim, SH & Cho, J 2011, 'Biotoxicity Of Nanoparticles: Effect Of Natural Organic Matter', Journal of nanoparticle Research, vol. 13, no. 7, pp. 3051-3061.View/Download from: Publisher's site
Various natural organic matters (NOM) with different characteristics in aquatic environment may affect toxicity of leased nanoparticles, owing to interactions between NOM and nanoparticles. This study investigated the effect of NOM and physical characteristics of the effluent organic matter (EfOM) on the ecotoxicity of quantum dots (QD) using Daphnia magna. Organic matter samples were obtained from: Yeongsan River (YR-NOM), Dongbuk Lake (DL-NOM), Damyang wastewater treatment plant (EfOM), and Suwannee River NOM (SR-NOM). The QD was composed of a CdSe core, ZnS shell, and polyethylene glycol coating. The average size of the investigated QD was 4.8, 56.5, and 25.0 nm determined by transmission electron microscopy, dynamic light scattering, and asymmetric flow field-flow fractionation, respectively. The relative hydrophobicity of NOM was investigated using both specific UV absorbance at 254 nm and XAD-8/4 resins. The sorption of NOM on the QD was measured using a fluorescence quenching method. The highest hydrophobicity was exhibited by the SR-NOM, while the lowest was recorded for the DL-NOM. All tested NOMs significantly reduced the acute toxicity of D. magna when adsorbed to QD, and the order of effectiveness for each NOM was as follows: SR-NOM>EfOM>YS-NOM>DL-NOM. The sorption of NOM on the QD surface caused a decrease in the fluorescence intensity of QD at increasing NOM concentration. This suggests that the NOM coating influenced the physicochemical characteristics ofQDin the internal organs of D. magna by inducing a reduced bioavailability. Results from this study revealed that NOM with relatively high hydrophobicity had a greater capability of inducing toxicity mitigation.
Manzouri, M & Shon, H 2011, 'Rectification methods for the fouling of ultrafiltration hollow-fibre membranes as a result of excessive soluble iron', Desalination and Water Treatment, vol. 32, pp. 437-444.View/Download from: Publisher's site
The aim of this study is to analyse process design parameters relating to a membrane bioreactor (MBR) membrane and chemical dosing systems as well as the characteristics of membrane foulant so as to identify a remedy for implementation. A qualitative research undertaken included electron microscopy analysis of the fouled membranes through a membrane autopsy which showed major inorganic deposits to the membrane surface, mainly comprising of iron. As it currently remains, the membrane system utilises citric acid for chemical in-place cleaning of the membranes. Analysis of results identifies the impact of membrane foulant to the operational performance of the treatment works and the impairment to effluent quality discharged to local waterways. Furthermore, an assessment into economic impacts is expected to show significant opportunities for improvements to operating costs as a direct result of cleaner membranes returning transmembrane pressures to normal levels during the permeate production cycle. The study also proposes optimisation strategies of the current cleaning process that is adequate for the level of ferric chloride dosed for phosphorous removal and odour control. Consideration is given to two types of strategies for rectification.
Na, S, Shon, H & Kim, J 2011, 'Minimization of excess sludge and cryptic growth of microorganisms by alkaline treatment of activated sludge', Korean Journal Of Chemical Engineering, vol. 28, no. 1, pp. 164-169.View/Download from: Publisher's site
Sludge solubilization was induced by the alkaline-thermal treatment to investigate the cryptic growth and reduction of a large amount of activated sludge produced from wastewater treatment. Activated sludge was divided into lysate, supernatant fraction and particulate fraction for a biodegradability test by cryptic growth. Sludge was reduced up to 78% at pH 13 and 44% at pH 10 using the single alkaline-thermal treatment. Also, it was found that alkalinethermal treatment at pH 13 increased the quantity of intracellular components generated by cell lysis and promoted the power of significant cell destruction. The neutralization of pH after the solubilized activated sludge led to high biodegradability of organic carbon sources generated by cell lysis. This can be utilized in minimizing activated sludge.
Na, S, Shon, H, Kim, JB, Park, HJ & Kim, J 2011, 'Preparation and characterization of titania nanoparticle produced from Ti-flocculated sludge with paper mill wastewater', Journal of Industrial and Engineering Chemistry, vol. 17, pp. 277-281.View/Download from: Publisher's site
Sludge disposal after flocculation with paper mill wastewater is one of the most costly and environmentally problematic challenges. In this study, an effective sludge recycling process was proposed using Ti-salt coagulant instead of the currently used Fe-salt. Paper mill wastewater flocculation using TiCl4 and FeCl3 coagulants was investigated for organic removal and precipitation efficiency. A large amount of titania nanoparticle was produced after incineration of sludge of Ti-salt flocculation in paper mill wastewater. The titania nanoparticle was characterized in terms of physical and chemical properties. Results showed that the removal efficiency of organic matter at the optimum concentrations of Ti- and Fe-salt was 69% and 65%, respectively. The removal of turbidity was 99%. Titania recovered from 600 8C incineration of the settled sludge consisted of the anatase titania structure. The titania from printing paper mill wastewater showed irregularly aggregated structures with round shape of dimension of 10â15 nm as a primary crystal growth. Various dopant materialswere found to be carbon (4.3%), magnesium (0.9%), aluminium (1.9%), silicon (1.7%), sulphur (0.7%) and calcium (3.8%). 60% of acetaldehyde concentration under UV irradiation was removed with the titania nanoparticles produced from the printing paper mill wastewater.
Okour, Y, Shon, H, Liu, H, Kim, JB & Kim, JH 2011, 'Seasonal variation in the properties of titania photocatalysts produced from Ti-salt flocculated bioresource sludge', Bioresource Technology, vol. 102, no. 9, pp. 5545-5549.View/Download from: Publisher's site
Ti-salt flocculation of biologically treated sewage effluent (BTSE) was carried out on monthly basis during one year to trace the seasonal variation in the properties of BTSE, Ti-salt flocculated BTSE and titania photocatalysts. Titania photocatalysts were produced from incineration of Ti-salt flocculated sludge at 600 Â°C. The physio-chemical properties of BTSE, Ti-salt flocculated BTSE and titania photocatalysts were investigated. The photocatalytic activity of titania was examined using different substrates of rhodamine B and humic acid under UV light irradiation. Results indicated that the flocculation performance of Ti-salt was not affected by the seasonal variation of BTSE. BTSE characteristics resulted in marginal effect in titania characterisation and photocatalytic activity. Titania photocatalysts produced from Ti-salt flocculated sludge in different seasons showed constant anatase phase, high BET surface area and high photocatalytic activity.
Sharma, G, Choi, J, Shon, H & Phuntsho, S 2011, 'Solar-powered electrocoagulation system for water and wastewater treatment', Desalination and Water Treatment, vol. 32, pp. 381-388.View/Download from: Publisher's site
The objective of this study is to investigate the feasibility of solar powered electrocoagulation (SPEC) for wastewater treatment using aluminium electrodes. Optimisation of various operating parameters such as pH, voltage/current, electrodes gap, pollutant concentration etc. were first performed using direct electrical current. SPEC reactor was designed by connecting with photovoltaic panel (PV) either directly or through a set of batteries and charge control system. SPEC process system was sensitive to variation of solar radiation when connected directly with PV panels. SPEC reactor operated for five different times in a day (4 April 2010) yielded highest organics removal of 85% for UV abs and turbidity removal of 87% at midday (10:00 AMâ2:00 PM) under optimum operating conditions. Use of batteries and charge controller with PV panels provided more consistent and efficient performance for the SPEC reactor. The variation in organics and turbidity removal was within the range of 10% for experiments conducted on three different times in a day (9 April 2010) with highest removals at 10:30 AM in the morning. This study indicates that, SPEC is a potential alternative for small scale decentralised water and wastewater purification system.
Sharma, G, Shon, H, Aryal, R & Phuntsho, S 2011, 'Performance evaluation of microfiltration with electrocoagulation and chemical coagulation pretreatment', Desalination and Water Treatment, vol. 34, pp. 141-149.View/Download from: Publisher's site
One of the significant parameters to be considered for evaluating the process and economic viability of crosssfl ow microfiltration (MF) is flux stability. The MF economics are dependent on the flux decay through the membrane caused by membrane fouling. This work aims to evaluate the performance of MF by electro and chemical coagulation as pretreatments. The performance of MF was found to be sensitive to pH of feed solution, coagulant dosing and generation time. Acrylonitrile butadiene styrene (ABS) MF membrane of pore size 0.4 Î¼m was used in this study. Without pretreatment normalised flux declined by 94% after 160 min of MF operation using model wastewater. However with pretreatments, the MF flux was significantly improved. The optimum performance for MF with both electro and chemical coagulation pretreatments occurred at isoelectric point where the highest removal of organic and turbidity was observed. With chemical coagulation under optimum conditions (30 mg/l alum dose and pH 6.5), MF did not experience any flux decline. MF performed better with chemical coagulation compared to electrocoagulation (EC). Also organic matter removal was found to be more for chemical coagulation than for EC.
Shon, H, Okour, Y, El Saliby, I, Kim, JB & Kim, J 2011, 'Effect of Phosphorous on the Properties of Titania Produced from Ti-Salt Flocculated Sludge in Water Treatment', Journal of Nanoscience & Nanotechnology, vol. 11, no. 8, pp. 7456-7458.View/Download from: Publisher's site
In this study, the removal of phosphorous (P) using Ti-salt flocculation of biologically treated sewage effluent (BTSE) was investigated for a year. The pH, alkalinity and concentration of P, before and after Ti-salt flocculation, were measured and compared. The sludge of Ti-salt flocculation was incinerated at 600 C to produce titania nanoparticles which found to be doped with P. Titania nanoparticles were characterised and their photocatalytic activity under UV light irradiation were also tested. Results indicated that the removal of P, which exceeded 97% in average, was not affected by the pH and the alkalinity of BTSE. The concentration of P in titania had no effect on the characteristics of titania nanoparticles in different seasons. Titania nanoparticles exhibited superior properties in terms of BET surface area and photocatalytic activity.
Zhao, Y, Gao, B, Cao, BC, Yang, Z, Yue, Q, Shon, H & Kim, JH 2011, 'Comparison of coagulation behavior and floc characteristics of titanium tetrachloride (TiCl4) and polyaluminum chloride (PACl) with surface water treatment', Chemical Engineering Journal, vol. 166, no. 2, pp. 544-550.View/Download from: Publisher's site
Coagulation behavior of Titanium tetrachloride (TiCl4) and polyaluminum chloride (PACl) was comparatively investigated in terms of the removal of turbidity and natural organic matter (NOM) with surface water. The growth, breakage and re-growth nature of flocs were also compared. The results show that the removals of chemical oxidation demand (CODMn) and dissolved organic carbon (DOC) were 51.5% and 78.4% at optimal dosage for TiCl4 and 29.8% and 41.0% for PACl, respectively. The floc breakage and re-growth indicated that TiCl4 and PACl coagulation occurred not only by charge neutralization but also by a form of sweep flocculation. Besides, flocs formed by PACl had better recoverability than the flocs formed by TiCl4. Sludge produced from TiCl4 flocculation was calcined at 600 â¦C to produce TiO2, and the photocatalytic activity in removing reactive brilliant red (K-2BP) was evaluated in comparison with commercially available TiO2 (P-25). The photocatalytic oxidation rates of K-2BP after 2 h photocatalytic reaction were 91.4% and 92.9% for as-prepared TiO2 and P-25, respectively.
Zhao, Y, Gao, B, Rong, H, Shon, H, Kim, H, Yue, Q & Wang, Y 2011, 'The impacts of coagulant aid-polydimethyldiallylammonium chloride on coagulation performances and floc characteristics in humic acid-kaolin synthetic water treatment with titanium tetrachloride', Chemical Engineering Journal, vol. 173, pp. 376-384.View/Download from: Publisher's site
Coagulation of humic acidâkaolin synthetic water was conducted with Titanium tetrachloride (TiCl4) and/or polydimethyldiallylammonium chloride (PD) to assess the effect of coagulant aid PD on coagulation behavior and floc characteristics. Coagulation behavior was investigated in terms of the reduction of turbidity and the removal of natural organic matter (NOM). The results show that the humic acid (HA) removal increased with the addition of PD depending on the doses of it and TiCl4, and the HA removal was more enhanced by PD at low TiCl4 doses than at higher ones. In addition, PD-TiCl4 (PD dosed firstly, followed by TiCl4 addition) gave better turbidity and HA removal than TiCl4-PD (TiCl4 dosed firstly, followed by PD addition) in this investigation. The growth, breakage, regrowth and fractal nature of flocs was investigated by use of Mastersizer 2000. TiCl4 plus cationic polymer PD exhibited an apparent improvement on floc size and floc grow rate, and they were both in the following order: PD-TiCl4 > TiCl4-PD > TiCl4. Compared with TiCl4, the dual-coagulants significantly improved the floc recoverability. Besides, the dual-coagulants gave more compact floc structure than TiCl4 coagulant at each coagulant dose under investigation and the values of fractal dimension (Df) were in the order of TiCl4-PD > PD-TiCl4 > TiCl4.
Zhao, Y, Gao, B, Shon, H, Cao, BC & Kim, JH 2011, 'Coagulation characteristics of titanium (Ti) salt coagulant compared with aluminum (Al) and iron (Fe) salts', Journal of Hazardous Materials, vol. 185, no. 2-3, pp. 1536-1542.View/Download from: Publisher's site
In this study, the performance of titanium tetrachloride (TiCl4) coagulation and flocculation is compared with commonly used coagulants such as aluminum sulfate (Al2(SO4)3), polyaluminum chloride (PACl), iron chloride (FeCl3), and polyferric sulfate (PFS) in terms of water quality parameters and floc properties. TiCl4 flocculation achieved higher removal of UV254 (98%), dissolved organic carbon (DOC) (84%) and turbidity (93%) than other conventional coagulants. Charge neutralization and physical entrapment of colloids within coagulant precipitates and adsorption, seemed to play a significant role during TiCl4 flocculation, while the main mechanism for conventional coagulants was bridge-aggregation and adsorption. The aggregated flocs after TiCl4 flocculation showed the fastest growth rate compared to the other coagulants, with the largest floc size (801m) occurring within 8 min. The floc strength factor of PACl, Al2(SO4)3, PFS, FeCl3 and TiCl4 was 34, 30, 29, 26 and 29, respectively, while the floc recovery factor of the TiCl4 coagulant was the lowest. Based on the results of the above study, it is concluded that the TiCl4 flocculation can reduce the hydraulic retention time of slow and rapid mixing, however, careful handling of sludge is required due to the low recoverability of the aggregated floc.
Zhao, Y, Gao, B, Shon, H, Kim, H, Yue, Q & Wang, Y 2011, 'Floc characteristics of titanium tetrachloride (TiCl4) compared with aluminum and iron salts in humic acid-kaolin synthetic water treatment', Separation and Purification Technology, vol. 81, pp. 332-338.View/Download from: Publisher's site
The floc strength and regrowth properties of TiCl4, FeCl3, and Al2 SO4)3 were comparatively evaluated using humic acidâkaolin synthetic water sample. At the given optimum dosage (20 mg/L as Ti, 8 mg/L as Fe, and 2 mg/L as Al, respectively), the floc growth, breakage and regrowth of TiCl4, FeCl3, and Al2(SO4)3 were investigated by use of a laser diffraction particle sizing device. Jar tests were conducted to investigate the impact of shear force and breakage period on floc breakage and re-aggregation potential. Results indicated that the responses of flocs to increasing shear force and breakage period depend on the coagulant used. The ability of floc to resist breakage decreased with the increase of shear force. Floc strength properties were also measured in response to increasing shear force, with the results suggesting that the order of floc strength was TiCl4 > FeCl3 > Al2(SO4)3. Floc regrowth of these three coagulants after exposure to high shear was limited, and flocs formed by TiCl4 displayed the weakest recoverability. Similar results were obtained when breakage period was different.
Zhao, Y, Gao, B, Shon, H, Kim, J & Yue, Q 2011, 'Effect of shear force, solution pH and breakage period on characteristics of flocs formed by Titanium tetrachloride (TiCl4) and Polyaluminum chloride (PACl) with surface water treatment', Journal of Hazardous Materials, vol. 187, no. 1, pp. 495-501.View/Download from: Publisher's site
The growth, breakage and regrowth nature of flocs formed by Titanium tetrachloride (TiCl4) and polyaluminum chloride (PACl) was comparatively evaluated with surface water treatment. A series of jar experiments were conducted to investigate the impacts of different operating parameters such as shear force, solution pH and a breakage period on floc strength and re-aggregation potential. Results indicated that the responses of flocs to different operating parameters depend on the coagulant used. The ability of floc to resist breakage decreased with the increase of shear force and breakage period. Floc strength properties were also measured in response to increasing shear force, with the results suggesting that the order of floc strength was TiCl4 > PACl. Floc regrowth of the two coagulants after exposure to high shear was limited, and flocs formed by TiCl4 displayed weaker recoverability. The flocs generated in acid conditions were more recoverable than those generated in alkaline conditions no matter which coagulant was used.
Zhao, Y, Gao, B, Shon, H, Wang, Y, Kim, JH & Yue, Q 2011, 'The effect of second coagulant dose on the regrowth of flocs formed by charge neutralization and sweep coagulation using titanium tetrachloride (TiCl4)', Journal of Hazardous Materials, vol. 198, pp. 70-77.View/Download from: Publisher's site
Characteristics of flocs formed by charge neutralization and sweep coagulation using titanium tetrachloride (TiCl4) were investigated with humic acidâkaolin suspension by continuous optical monitoring. This paper focused on the regrowth ability of broken flocs after addition of second TiCl4 dose. Variation of floc size and the fractal dimension of flocs versus second TiCl4 dose after regrowth were investigated. Second TiCl4 dose was added during the floc breakage period, and addition time of second TiCl4 dose was also investigated. The results showed that, when coagulated by charge neutralization at pH 6, an appropriate second TiCl4 dose improved regrowth ability of broken flocs at low initial TiCl4 doses. While for high initial TiCl4 doses, second TiCl4 dose lowered floc re-growth ability. When coagulated by sweep coagulation at pH 10, second TiCl4 dose made regrown flocs larger than those without second TiCl4 dose. Floc structure analysis showed that it was determined by not only the fractal dimension of flocs, but also the chemical characteristics of floc surface. Addition time of second TiCl4 dose had a great effect on floc regrowth ability, suggesting that the broken flocs had better regrowth when second TiCl4 dose was added at the end of the breakage period.
The advantage of the use of photocatalysts to treat persistent organic pollutants (POP) was demonstrated with the decomposition of trimethoprim (TRI), an antibiotic most frequently detected in municipal wastewaters and surface waters. In this study, the oxidation process by UV/TiO2 was employed as an alternative to advanced oxidation process (AOP) to remove residual antibiotics from water. High concentrations of TRI were used to study the efficiency of photocatalysis. Both batch and continuous photoreactors were used. The decomposition of TRI by TiO2/UV photooxidation occurred gradually over time. On the other hand, with UV irradiation alone, the reduction of TRI mineralization was relatively small. The effect of light intensity showed there was no significant impact of UV light intensity on the degradation of TRI in the range of increasing intensities studied. The simulation using first-order kinetics provided a good fit with the experimental data. In the continuous system, the feed flow rate was adjusted to maximize the percentage of mineralization of targeted compounds inside the photoreactor. A lower flow rate, i.e., higher detention time, achieved higher percentage of TRI mineralization. The results indicated that TiO2/UV irradiation was effective in removing TRI.
Kus, BG, Kandasamy, JK, Vigneswaran, S & Shon, H 2011, 'Water Quality in Rainwater Tanks in Rural and Metropolitan Areas of New South Wales, Australia', Journal of Water Sustainability, vol. 1, no. 1, pp. 33-43.
This paper compares the water quality of rainwater tanks throughout the Sydney metropolitan area to that in rural New South Wales, Australia. The water quality is compared against the Australian Guidelines for Water Recycling (AGWR) to determine if the untreated rainwater from both areas can be considered suitable for non-potable water supply without filtration. Additionally this paper reports on a set of experiments where rainwater collected from a typical domestic roof in Sydney, New South Wales, Australia was treated by a pre-treatment of granular activated carbon (GAC) adsorption filter followed by micro-filtration. The GAC column removed the pollutants through an adsorption mechanism. GAC is a macroporous solid with a very large surface area providing many sites for adsorption and it is this property that makes it an efficient adsorbent. The parameters analysed were ammonia, anions and cations, heavy metals, nitrate and nitrite, pH, total hardness, total organic carbon, total suspended solids and turbidity. The results indicate that before treatment, the rainwater already complied to many of the parameters specified in the AGWR, certain pollutants have the potential at times to exceed the AGWR. The water quality was within the AGWR limits after the treatment. The micro- filtration flux values demonstrate that rainwater was able to be filtered through the membranes under low gravitational heads that are typically available in a rainwater tank while still producing sufficient membrane flux and pollutant removal rates.
Kus, BG, Kandasamy, JK, Vigneswaran, S, Shon, H & Areerachakul, N 2011, 'Water quality of membrane filtered rainwater', Desalination and Water Treatment, vol. 32, pp. 208-213.View/Download from: Publisher's site
Although most Australians receive their domestic supply from reticulated mains or town water, there are vast areas with very low population densities and few reticulated supplies. In many of these areas rainwater collected in tanks is the primary source of drinking water. Heavy metals are a concern as their concentration in rainwater tanks was found to exceed recommended levels suitable for human consumption. This paper reports on experimental investigations where rainwater collected from a typical domestic roof in Sydney, Australia was treated in two stages of filtration including granular activated carbon (GAC) as a pre-treatment adsorption filter media and a metallic membrane from Steri-flow Filtration Systems Pty. Ltd. The quality of the treated rainwater was compared against the drinking water standards to determine its suitability as a supplement for potable water supply. The pollutants analysed were heavy metals, total coliform and faecal coliforms, total organic carbon, total suspended solids and turbidity. The results indicate that before treatment, the rainwater already complied with many of the parameters specified in drinking water standards. The metallic membrane performed well in removing suspended particles and heavy metals from the rainwater. The performance of the metallic membrane is greatly improved by the use of pre-treatment such as GAC which was used in this experiment.
Liu, H, Shon, H, Okour, Y, Song, W & Vigneswaran, S 2011, 'Photocatalytic Degradation of Acid Red G by Bismuth Titanate in Three-phase Fluidized Bed Photoreactor', Journal of Advanced Oxidation Technologies, vol. 14, no. 1, pp. 116-121.View/Download from: Publisher's site
The objectives of this study were to prepare a high-performance bismuth titanate photocatalyst and to develop a novel photocatalytic reactor with three-phase internal circulating fluidized bed photoreactor (TPICFBP). Bismuth titanate photocatalyst was hydrothermally prepared under optimum operating parameters such as hydrothermal temperature, reaction time and molar ratio of Bi to Ti. The photocatalytic activity of bismuth titanate using TPICFBP was evaluated for the photocatalytic degradation of Acid Red G (ARG). The photodegradation of ARG over Bi12TiO20 (12:1 molar ratio of Bi to Ti) under acidic condition showed the highest removal rate (92%) with wastewater flux and operating time of 10 L/h and 3 h, respectively.
Liu, H, Shon, H, Sun, X, Vigneswaran, S & Nan, H 2011, 'Preparation and characterization of visible light responsive Fe2O3TiO2 composites', Applied Surface Science, vol. 257, no. 13, pp. 5813-5819.View/Download from: Publisher's site
In this studywepresent the effects of iron oxide (Fe2O3) on titanium dioxide (TiO2) in synthesising visiblelight reactive photocatalysts. A Fe2O3âTiO2 composite photocatalyst was synthesized from Fe2(SO4)3 and Ti(SO4)2 by a ethanol-assisted hydrothermal method. The preparation conditions were optimized through the investigation of the effects of hydrothermal temperature and time as well as molar ratio of Ti to Fe on the photocatalytic activity. The visual, physical and chemical properties of the Fe2O3âTiO2 composites were investigated. The results showed that -Fe2O3 and anatase TiO2 were present in the composites. The Fe2O3âTiO2 synthesized under optimum condition consisted of mesoporous structure with an average pore size of 4 nm and a surface area of 43m2/g. Under visible and solar light irradiation, the photocatalytic activity of optimized sample was significantly higher than that of pure TiO2. This sample led to a photodegradation efficiency of 90% and 40% of auramine under visible light and solar light, respectively.
Liu, H, Xia, T, Shon, H & Vigneswaran, S 2011, 'Preparation of titania-containing photocatalysts from metallurgical slag waste and photodegradation of 2,4-dichlorophenol', Journal of Industrial and Engineering Chemistry, vol. 17, no. 3, pp. 461-467.View/Download from: Publisher's site
A low cost, high performance titania-containing metallurgical slag photocatalysts (TCMSPx, x = H2SO4, HNO3, HCl) were prepared using a hydrothermal method. The prepared TCMSPx were characterized in terms of visual, physical and chemical properties. The photocatalytic activity of the TCMSPx was evaluated via the photodegradation of 2,4-dichlorophenol (2,4-D) in aqueous solution. The results showed that the characteristics and photocatalytic activity of TCMSPx were strongly affected by acidic solutions used during the acidolysis. TCMSPH2SO4 exhibited better characteristics and higher photocatalytic activity than TCMSPHNO3 and TCMSPHCl. OH radicals from TCMSPH2SO4 were produced under UV, visible and solar light irradiation. The degree of photodegradation of 2,4-D by TCMSPH2SO4 was 80.1%, 50.0% and 61.5% under UV, visible and solar light irradiation respectively. In addition, the removal of chlorine functional group on the 2,4-D benzene ring and the production of intermediates during 2,4-D photodegradation were monitored using ion chromatography, UVâvis spectra and high performance liquid chromatography of 2,4-D before and after photodegradation.
Phuntsho, S, Listowski, A, Shon, H, Le-Clech, P & Vigneswaran, S 2011, 'Membrane autopsy of a 10 year old hollow fibre membrane from Sydney Olympic Park water reclamation plant', Desalination, vol. 271, no. 1-3, pp. 241-247.View/Download from: Publisher's site
Membrane autopsy was performed for a 10 year old polypropylene (PP) hollow fibre microfiltration membrane from Sydney Olympic Park water reclamation plant. The properties of the membrane were studied using scanning electron microscope (SEM) imaging, contact angle, bubble test, thermogravimetric analysis, tensile strength test and functional group. The old and fouled membrane exhibited a significant difference in surface properties and material strength in comparison to the virgin membrane. The old and fouled membrane surface is less hydrophilic and less negatively charged indicating that aged membrane is more vulnerable to fouling than virgin membrane. The fibre material of the old fouled membrane appears less flexible and brittle. Foulant analysis indicated that major components of the metallic elements were silicon and calcium. The dissolved organic matter was mainly composed of biopolymers (hydrophilic) and humic substances (hydrophobic).
Phuntsho, S, Shon, H, Hong, S, Lee, S & Vigneswaran, S 2011, 'A novel low energy fertilizer driven forward osmosis desalination for direct fertigation: Evaluating the performance of fertilizer draw solutions', Journal Of Membrane Science, vol. 375, no. 1-2, pp. 172-181.View/Download from: Publisher's site
Forward osmosis (FO) is a novel and emerging low energy technology for desalination. It will be particularly more attractive, if the draw solution separation and recovery are not necessary after FO process. The application of this new concept is briefly described here in this paper for the desalination of saline water for irrigation, using fertilizer as a draw agent. Instead of separating the draw solution from desalinated water, the diluted fertilizer draw solution can be directly applied for fertigation. We report the results on the commonly used chemical fertilizers as FO draw solution. Based on the currently available FO technology, about nine different commonly used fertilizers were finally screened from a comprehensive list of fertilizers and, their performances were assessed in terms of pure water flux and reverse draw solute flux. These results indicate that, most soluble fertilizers can generate osmotic potential much higher than the sea water. The draw solutions of KCl, NaNO3 and KNO3 performed best in terms of water flux while NH4H2PO4, (NH4)2HPO4, Ca(NO3)2 and (NH4)2SO4 had the lowest reverse solute flux. Initial estimation indicates that, 1 kg of fertilizer can extract water ranging from 11 to 29 L from sea water.
Phuntsho, S, Shon, H, Vigneswaran, S & Cho, J 2011, 'Assessing membrane fouling potential of humic acid using flow field-flow fractionation', Journal Of Membrane Science, vol. 373, no. 1-2, pp. 64-73.View/Download from: Publisher's site
Flow field-flow fractionation (FlFFF), although a separation technique, has many similarities with the crossflow membrane filtration system, thereby making it an ideal tool for studying membrane fouling. This study reports the assessment of the fouling potential of humic acid on ultrafiltration membrane using asymmetrical FlFFF. The fouling potential of organic matter was assessed by quantifying the reversible and irreversible adsorption of humic acid on the membrane through analysis of FlFFF fractogram. A strong correlation was observed between the reversible/irreversible adsorption data analysed and the membrane fouling potential. This assessment was further complimented by moment analysis results in order to interpret the fouling potential of humic acid. However, further researches are necessary before this approach can serve as an alternative index for measuring membrane fouling propensity.
Shon, H, Vigneswaran, S, Kandasamy, JK, Kim, J & Kim, J 2011, 'Advanced Characterization Techniques Of Organic Matter In Aqueous Solutions', Journal of the Korean Industrial and Engineering Chemistry, vol. 22, no. 1, pp. 1-14.
Water is the most precious resource to human being, but it is polluted by different organic compounds. Organic matter (OM) in aqeous solutions is one of the important parameters of concern for human and environmental impact, and thus, it is essential to
Jegatheesan, V, Shu, L, Nghiem, LD, Shon, HK & Chang, C-Y 2011, 'Challenges in Environmental Science and Engineering CESE-2010 26 September-1 October 2010, The Sebel, Cairns, Queensland, Australia Total Water Management for the Sustainability of Freshwater in the Future', DESALINATION AND WATER TREATMENT, vol. 32, no. 1-3, pp. 1-3.View/Download from: Publisher's site
El Saliby, I, Shon, H, Kandasamy, JK & Kim, J 2011, 'Synthesis, characterisation and separation of photoreactive Hydrogen-titanate nanofibrous channel', Separation and Purification Technology, vol. 77, no. 2, pp. 202-207.View/Download from: Publisher's site
Australia is the world's largest wool producing country, accounting for about 25â30% of world production. As a biotemplate, we explored the possibility of using wool to produce micro-channel of Hydrogentitanate nanofibres through morphology transcription of wool microfibres. Hydrothermal method was adopted to synthesise titanate nanofibres. A facile method of impregnation followed by incineration at 600 â¦C was utilised to prepare the nanofibrous channel. Anatase undoped nanofibrous (average nanofibre diameter = 44 nm) channel of around 50min length and an average diameter of 9.5mwere obtained. The photocatalytic activity of nanofibrous channel was monitored under UV irradiation for the decomposition of humic acid in aqueous solution using an aerobic batch reactor system. The photodegradation results showed that UV254 absorbing moeities and DOC were respectively reduced by 82% and 66% after 3 h of photoreaction at 1 g/L catalyst load. The novel nanofibrous channel could be easily separated from the aqueous suspension by sedimentation after the end of the photocatalytic reaction.
Singh, G, Kandasamy, JK, Shon, H & Cho, J 2011, 'Measuring treatment effectiveness of urban wetland using hybrid water quality - Artificial neural network (ANN) model', Desalination and Water Treatment, vol. 32, pp. 284-290.View/Download from: Publisher's site
Constructed wetlands are now commonly used as tertiary treatment for urban stormwater. The wetlands have primary advantage over other forms of treatment as they remove dissolved organics and heavy metals in conjunction with other pollutants. The effectiveness of a wetland is a primary concern for validating its compliance with design objectives and regulatory requirements. The treatment in a wetland is however complex and is dependent on input pollutants, hydraulics, physicochemical balance and biota within the wetland. Several models are available for wetlands but have limitations in simulating the physico-chemical and biological processes within the wetland. The aim of this paper is to introduce a hybrid modelling approach that involves both a deterministic model and artificial neural network (ANN) for testing the effectiveness of a constructed wetland at Olympic Park, Homebush, Sydney, Australia. This novel approach allows a combination of calibrated water quality and neural based models to predict the water quality from the wetland. The models were calibrated and validated using water quality monitoring data measured for eight months in both influent and effluent streams of the wetland. The calibrated hybrid models were then tested for treatment effectiveness for range of wet, dry and median flows conditions within the catchments. A water quality index was developed and used to quantify the effectiveness of the wetland.
Kim, D, Shon, H, Phuntsho, S & Cho, J 2010, 'Determination of the Apparent Charge of Natural Organic Matter', Separation Science and Technology, vol. 45, no. 3, pp. 339-345.View/Download from: Publisher's site
The charge of natural organic matter (NOM) is an important parameter for understanding the membrane fouling and NOM removal mechanism with charged membrane. However, there is a lack of technology to make direct measurement of the NOM charge. In this study, we report a novel concept of measuring an apparent charge of the NOM using selectivity coefficient. The apparent charges of three different NOM containing different structures were evaluated to validate this proposed method. The apparent charge of the NOM exhibited a good correlation with specific UV absorbance of the NOM. This apparent charge is therefore a useful indicator for predicting the membrane fouling and NOM removal in membrane filtration technology.
Kim, JB, Park, HJ, Shon, H, Cho, DL, Kim, G, Choi, S & Kim, J 2010, 'Preparation of Ti02 Nanoparticle from Ti-Salt Flocculated Sludge with Dye Wastewater', Journal of Nanoscience and Nanotechnology, vol. 10, no. 5, pp. 3260-3265.
Dye wastewater flocculation using TiCl4 and FeSO4 coagulants was studied for organic removal and precipitation efficiency. Moreover, TiCl4 was assessed in a pilot-scale flocculation process to investigate organic removal and solution pH effect. A large amount of TiO2 was produced from sludge of Ti-salt flocculation in dye wastewater. This flocculation process simultaneously reduces a large amount of sludge produced from wastewater. The TiO2 nanoparticle was characterized in terms of physical and chemical properties. Results showed that 77.6% of organic matter was removed from dye wastewater when using FeSO4 as coagulant, while TiCl4 degraded 75.9% of organic matter. On the other hand, floc precipitation efficiency was better for TiCl4 if compared with FeSO4. The optimum concentration of TiCl4 for pilot-scale flocculation was found to be equal to 2.1 g/L. DWT (Dye wastewater titania) size was 15-20 nm, mainly doped with carbon atoms and exhibited a dominant anatase structure. DWT was similar to P-25 in decomposing acetaldehyde under UV-irradiation and complete photocatalytic degradation was achieved after 140 min.
Kim, JK, Seol, D, Shon, H, Kim, G & Kim, JK 2010, 'Preparation and characterization of titania nanoparticles from titanium tetrachloride and titanium sulfate flocculation of dye wastewater', Journal of the Japan Petroleum Institute, vol. 53, no. 3, pp. 167-172.View/Download from: Publisher's site
Titanium dioxide (TiO2) is the most widely used metal oxide for environmental applications, cosmetics, paints, electronic paper and solar cells, so demand is increasing rapidly. TiO2 can be produced from Ti-flocculated sludge, which is superior to the co
Lee, E, Shon, H & Cho, J 2010, 'Biofouling characteristics using flow field-flow fractionation: Effect of bacteria and membrane properties', Bioresource Technology, vol. 101, no. 5, pp. 1487-1493.View/Download from: Publisher's site
In this study, membrane biofouling caused by bacteria that have different characteristics was evaluated using flow field-flow fractionation (FlFFF). Three different bacteria which differed from size and shape (Staphylococcus epidermidis, Escherichia coli, Flavobacterium lutescens) were investigated with GM ultrafiltration (UF, rough with a low negative surface charge and relatively high hydrophobicity) and NE70 nanofiltration (NF, smooth with a high negative surface charge and relatively low hydrophobicity) membranes. The FlFFF retention time of S. epidermidis, E. coli and F. lutescens was highly influenced by the ionic strength of the solution and the surface polarity of the membranes and bacteria. The NF membrane was found to have a higher potential of biofouling than the UF membrane with the bacteria tested in this study. E. coli was the most significant biofoulant among the bacteria tested on both membrane surfaces based on FlFFF retention times compared to other bacteria.
Na, SH, Shon, H, Kim, JB, Park, HJ, Cho, DL, El Saliby, I & Kim, JH 2010, 'Recycling of excess sludge using titanium tetrachloride (TiCl4) as a flocculant aid with alkaline-thermal hydrolysis', Journal of Industrial and Engineering Chemistry, vol. 16, no. 1, pp. 96-100.View/Download from: Publisher's site
The highly strengthened treatment and disposal of excess sludge based on economic and environmental regulation factors is one of the important issues to be dealt with in the activated sludge process. In this study, the reduction and recycling technology of excess sludge were investigated for the aim of achieving a zero emission of excess sludge produced from the activated sludge process using titanium tetrachloride (TiCl4) as a flocculant aid with alkaline-thermal hydrolysis. Alkaline-thermal hydrolysis of excess sludge was obtained 73% and 40% reduction rate at pH 13 (60 8 Â°C) and pH 11 (60 8 Â°C), respectively. Flocculation was carried out using a Ti-salt flocculant and the collected sludge was dewatered and incinerated at 600 Â°C to produce TiO2 nanoparticles. The amount of total suspended solids and volatile suspended solids was significantly decreased with pH increase. The optimal dose of Ti-salt flocculation aid to improve dewatering ability of sludge breakage was 23.95 Ti-mg lâ1. Also, in the batch culture, the supernatant after flocculation and the organic matter released from the lysed sludge were found to be useful as a source of energy for the growth of microorganisms during the aerobic operations period. TiO2 produced from Ti-salt flocculation of excess sludge (TES) was characterized by X-ray diffraction, scanning electron microscopy/energy dispersive X-ray and photocatalytic activity.
Okour, Y, Shon, H, El Saliby, I, Naidu, R, Kim, JB & Kim, JH 2010, 'Preparation and characterisation of titanium dioxide (TiO2) and thiourea-doped titanate nanotubes prepared from wastewater flocculated sludge', Bioresource Technology, vol. 101, no. 5, pp. 1453-1458.View/Download from: Publisher's site
In this study, titanium (Ti), ferric (Fe) and aluminum (Al) salt flocculants were compared for their efficiency in treating wastewater collected from Sydney Olympic Park wastewater treatment plant by following the jar test procedure. Produced sludge from Ti-salt flocculation was dried and titanium dioxide (TiO2) nanoparticles were generated after the incineration of sludge produced from the Ti-salt flocculation of wastewater. Later on, titanate nanotubes were synthesized after TiO2 nanoparticles were hydrothermally treated with 10 N NaOH solution at 130 Â°C for 24 h. Titanate nanotubes were either acid or deionised water-washed, while thiourea-doping was employed to produce visible light-responsive nanotubes. Wastewater flocculation using Ti-salt was found to be as efficient as Fe and Al flocculation in terms of turbidity and DOC removal. XRD results showed that the anatase structure was predominant for TiO2 nanoparticles, while thiourea-doped titanate nanotubes only indicated anatase structure with an increased crystallinity after being crystallized at 600 Â°C. The photocatalytic activity of all photocatalysts was evaluated using the photooxidation of acetaldehyde. Thiourea-doped nanotubes showed a greater photocatalytic activity than as-prepared TiO2 nanoparticles, deionised water-washed, acid-washed titanate nanotubes and P25 under UV and visible light irradiation.
Chanan, AP, Vigneswaran, S, Kandasamy, JK & Shon, H 2010, 'Chemical-assisted physico-biological water mining system', Institution of Civil Engineers. Proceedings. Water Management, vol. 163, no. 9, pp. 469-474.View/Download from: Publisher's site
Water mining is the process of extracting valuable water from a sewerage network by treating raw sewage to high standards. A range of commercially viable water mining treatment technologies are now available to treat sewage to specified water quality targets. Most of these technologies have minimal plant footprint requirements, making them suitable for decentralised operations. This paper discusses a hybrid water mining system that includes chemically assisted fine solids separation followed by a biological treatment process. Results from the first proof testing of this water mining system in Sydney, Australia are presented. The results confirm the suitability of the hybrid system for producing high-quality water for non-potable reuse.
Chinu, KJ, Johir, MH, Vigneswaran, S, Shon, H & Kandasamy, JK 2010, 'Assessment of pretreatment to microfiltration for desalination in terms of fouling index and molecular weight distribution', Desalination, vol. 250, no. 2, pp. 644-647.View/Download from: Publisher's site
In this study, different processes such as flocculation with ferric chloride (FeCl3) and deep bed filtration (sand filtration and dual media filtration) as a pre-treatment to microfiltration (MF) were used for seawater desalination. The performance of these pre-treatments was determined in terms of silt density index (SDI) and modified fouling index (MFI) and flux decline in MF. Flux decline of MF with seawater was 45% without any pre-treatment, 42% after pre-treatment of FeCl3 flocculation, 24% after pre-treatment of sand filtration with in-line coagulation and 22% after pre-treatment of dual media filtration (sand and anthracite), respectively. MFI and SDI also indicated that deep bed filtration with in-line flocculation was better pretreatment than flocculation alone. Detailed molecular weight distribution (MWD) of seawater organic matter was examined after different pretreatments. MWD of the initial seawater mainly ranged from 1510 Da to 130 Da. Deep bed filtration with in-line flocculation removed relatively large molecular weight of organic matter (1510â1180 Da), while the small molecular weights (less than 530 Da) were not removed.
Chinu, KJ, Vigneswaran, S, Erdei, L, Shon, H, Kandasamy, JK & Ngo, H 2010, 'Comparison of fouling indices in assessing pre-treatment for seawater reverse osmosis', Desalination and Water Treatment, vol. 18, no. 1-5, pp. 187-191.View/Download from: Publisher's site
In this study, different processes such as flocculation with ferric chloride (FeCl3) and deep bed filtration (sand filtration and dual media filtration) as a pre-treatment were used for seawater desalination. The performance of these pre-treatments was determined in terms of silt density index (SDI) and modified fouling index by using microfilter (MF-MFI), ultrafilter (UF-MFI), and nanofilter (NF-MFI) membrane. MFI and SDI indicated that deep bed filtration with in-line flocculation was better pre-treatment than flocculation alone as colloidal particles are removed after this pretreatment. UF-MFI and NF-MFI indicated that these pretreatment cannot remove dissolved organic matter as the fouling reduction was smaller. Detailed molecular weight distribution (MWD) of seawater organic matter was examined after different pretreatments. MWD of the initial seawater mainly ranged from 1510 Da to 130 Da. Deep bed filtration with in-line flocculation removed relatively large molecular weight of organic matter (1510â1180 Da), while the small molecular weights (less than 530 Da) were not removed.
El Saliby, I, Shon, H, Okour, Y, Vigneswaran, S, Senthilnanthanan, M & Kandasamy, JK 2010, 'Production of Titanium Dioxide Nanoparticles and Nanostructures from Dye Wastewater Sludge - Characterisation and Evaluation of Photocatalytic activity', Journal of Advanced Oxidation Technologies, vol. 13, no. 1, pp. 15-20.
Producing a useful catalyst (TiO2) from sludge is possible after the incineration of sludge produced from the flocculation of wastewater by Ti-salts. In this study, TiO2 was successfully produced from dye wastewater sludge. Titanate nanotubes and nanoaggregates were produced through alkaline-hydrothermal and hydrogen peroxide treatments, respectively. Catalysts were characterised using scanning electron microscope and BET surface measurement. The photocatalytic activity was monitored for the photodegradation of organics in synthetic wastewater (SWW) and the photodecomposition of gas acetaldehyde. Nanotubes with a high surface area of 155.83 m2/g were obtained by alkaline-hydrothermal treatment, while lower surface area (65.22 m2/g) nanoaggregates were synthesized after hydrogen peroxide treatment. In general, nanoparticles, nanotubes and nanoaggregates showed mild photocatalytic activity. All catalysts showed similar photocatalytic activity for the photodecomposition of organics in SWW and the photodecomposition of acetaldehyde.
Kus, BG, Kandasamy, JK, Vigneswaran, S & Shon, H 2010, 'Analysis of first flush to improve the water quality in rainwater tanks', Water Science and Technology, vol. 61, no. 2, pp. 421-428.View/Download from: Publisher's site
Although most Australians receive their domestic supply from reticulated mains or town water, there are vast areas with very low population densities and few reticulated supplies. In many of these areas rainwater collected in tanks is the primary source of drinking water. Heavy metals have recently become a concern as their concentration in rain water tanks was found to exceed recommended levels suitable for human consumption. Rainwater storage tanks also accumulate contaminants and sediments that settle to the bottom. Although not widely acknowledged, small amounts of contaminants such as lead found in rain water (used as drinking water) may have a cumulative and poisonous effect on human health over a life time. This is true for certain factors that underlie many of the chronic illnesses that are becoming increasingly common in contemporary society. The paper reports on a study which is part of a project that aims to develop a cost effective in-line filtration system to improve water quality in rainwater tanks. To enable this, the characteristics of rainwater need to be known. One component of this characterization is to observe the effects of the first flush on a rainwater tank. Samples of the roof runoff collected from an urban residential roof located in the Sydney Metropolitan Area in the initial first few millimetres of rain were analysed. The results show that bypassing the first 2mm of rainfall gives water with most water quality parameters compliant with the Australian Drinking Water Guidelines (ADWG) standards. The parameters that did not comply were lead and turbidity, which required bypassing approximately the first 5mm of rainfall to meet ADWG standards. Molecular weight distribution (MWD) analysis showed that the concentration of rainwater organic matter (RWOM) decreased with increasing amount of roof runoff.
Kus, BG, Kandasamy, JK, Vigneswaran, S & Shon, H 2010, 'Water quality characterisation of rainwater in tanks at different times and locations', Water Science and Technology, vol. 61, no. 2, pp. 429-439.View/Download from: Publisher's site
Rainwater collected from ten domestic roofs in Sydney and from one in Wollongong, a town south of Sydney, Australia was analysed to determine the water quality and to compare against the Australian Drinking Water Guidelines (ADWG) to determine its suitability as a potable water supply. The pollutants analysed were 13 heavy metals, 8 salts & minerals, pH, ammonia, orthophosphate, conductivity, water hardness, turbidity, total suspended solids, Total dissolved salts & Bicarbonate. The results indicate that the rainwater tested complied to most of the parameters specified in the ADWG. Molecular weight distribution of organic matter from one of the domestic rainwater tanks was analysed in terms of the effects of aging and roof contact. Molecular weight distribution of organic matter in rainwater showed prominent peaks at 37,500 daltons may be due to biopolymers, 850 Da to humic substances, 500 Da to building blocks, 220 Da to low MW acids, and less than 220 Da to amphiphilics. The findings also indicate that the first flush volumes that by-passed the tank can have a significant influence on the water quality in the rainwater tank.
Lebegue, J, Aryal, R, Shon, H, Vigneswaran, S, Heran, M & Grasmick, A 2010, 'Identification and quantification of foulant in submerged membrane reactor', Desalination and Water Treatment, vol. 24, no. 1-3, pp. 278-283.View/Download from: Publisher's site
In submerged membrane system, membrane fouling is linked to the reversible accumulation of macromolecules and solids on the membrane surface and the irreversible sorption of soluble molecules inside the pores. In the first part of the paper, the fouling was analysed at two different aeration rates through the determination of membrane resistance due to (a) sludging (Rsludging), (b) irreversible biofilm (Rbiofilm) and (c) adsorption of organic (Radsorption). These results confirm the importance of aeration for sludge control in the bundle. In the second part of the paper, irreversible foulant obtained at different aeration rates were characterised. Membrane air flow rate limits adsorption of biopolymers onto or into the membrane surface.
Lee, J, Johir, MH, Chinu, KJ, Shon, H, Vigneswaran, S, Kandasamy, JK, Kim, CW & Shaw, K 2010, 'Novel pre-treatment method for seawater reverse osmosis: Fibre media filtration', Desalination, vol. 250, no. 2, pp. 557-561.View/Download from: Publisher's site
A high rate fibre filter was used as a pre-treatment to seawater reverse osmosis (SWRO) to reduce membrane fouling. Seawater was drawn from Chowder Bay where the Sydney Institute of Marine Science, Australia is located. A lab-scale fibre filter with a height of 1000 mm and a diameter of 30 mm was used in conjunction with in-line coagulation. The effect of operating the fibre filter with different packing densities (105, 115 kg/m3) and filtration velocities (40, 60 m/h) was investigated in terms of silt density index (SDI10), modified fouling index (MFI), pressure drop (ÎP), turbidity and molecular weight distribution (MWD). The use of in-line coagulation improved the performance of fibre filter as measured by the MFI and SDI. Regardless of filtration velocity and packing density the MFI and SDI10 values remained low as did the turbidity until the end of the filtration run. The MWD analysis showed the removal efficiencies of organic materials like biopolymers, fulvic acids, low MW acids for even experiments with the highest filtration velocity (60 m/h) and lowest packing density (105 kg/m3). This pre-treatment has a small foot print as it has the capacity of operating at a very high filtration velocity
Park, KH, Shim, WG, Shon, H, Lee, SG, Ngo, H, Vigneswaran, S & Moon, H 2010, 'Adsorption Characteristics of Acetaldehyde on Activated Carbons Prepared from Corn-Based Biomass Precursor', Separation Science and Technology, vol. 45, no. 8, pp. 1084-1091.View/Download from: Publisher's site
The ACs (R-1/2 and R-1/4) having two different textual and chemical properties are prepared from corn-based biomass precursor and evaluated together with a wood-based activated carbon (WAC) at room temperature using a gas chromatograph. The results obtained from the correlation studies indicate that the pore size distribution (below 8A Ë ) and the relatively lower energetic heterogeneity of ACs on acetaldehyde adsorption are considerable factors rather than that of a specific surface area and surface chemistry. The adsorption equilibrium of ACs is well correlated with the Sips equation. The pseudo second-order equation was better in describing the ACsâ adsorption kinetic of acetaldehyde.
Phuntsho, S, Dulal, I, Yangden, D, Tenzin, U, Herat, S, Shon, H & Vigneswaran, S 2010, 'Studying Municipal Solid Waste Generation And Composition In The Urban Areas Of Bhutan', Waste Management & Research, vol. 28, no. 6, pp. 545-551.View/Download from: Publisher's site
Bhutan lacks the solid waste data which are essential parameters for planning and scheduling of municipal solid waste management (MSWM) systems. The first ever large-scale research survey on solid waste generation and characterization in the urban areas
Senthilnanthan, M, Ho, D, Vigneswaran, S, Ngo, H & Shon, H 2010, 'Visible light responsive ruthenium-doped titanium dioxide for the removal of metsulfuron-methyl herbcide in aqueous phase', Separation and Purification Technology, vol. 75, no. 3, pp. 415-419.View/Download from: Publisher's site
Titanium dioxide (TiO2) under UV light irradiation is one of the effective treatment methods to reduce the concentration of synthetic organic compounds in water. Nevertheless, only a small amount of UV light is absorbed in the solar light. This makes the less use of TiO2 for environmental applications. In this study, we prepared Ru-doped visible light responsive (VLR) TiO2 to improve visible light absorption and characterized it in terms of physical and chemical properties. The photocatalytic activity of VLR Rudoped TiO2 was investigated to remove metsulfuron-methyl (MSM) in aqueous phase. The Ru-doped TiO2 at different Ru concentrations was found to have the anatase phase. The undoped and Ru-doped TiO2 consisted of regular round shape. The photocatalytic activity of VLR photocatalyst was significantly improved on the addition of Ru from 40% for undoped TiO2 to 80% for Ru-doped TiO2. The removal efficiency of MSM was proportional to the increasing Ru-doped TiO2 under visible light. As the calcined temperature increased from 300 to 900 â¦C, the degradation efficiencies moderately changed from 65 to 90%. However, the effect of calcination duration was marginal on the photodegradation of MSM.
Shon, H, Phuntsho, S, Vigneswaran, S, Kandasamy, JK, Kim, JB, Park, HJ & Kim, IS 2010, 'PVDF-TiO2 Coated microfiltration membranes: preparation and characterization', Membrane Water Treatment, vol. 1, no. 3, pp. 193-206.View/Download from: Publisher's site
Organic fouling and biofouling pose a significant challenge to the membrane filtration process. Photocatalysis-membrane bybrid system is a novel idea for reducing these membranes fouling however, when TiO2 photocatalyst nanoparticles are used in suspension, catalyst recovery is not only imposes an extra step on the process but also significantly contributes to increased membrane resistance and reduced permeate flux. In this study, TiO2 photocatalyst has been immobilized by coating on the microfiltration (MF) membrane surface to minimize organic and microbial fouling. Nano-sized TiO2 was first synthesized by a sol-gel method. The synthesized TiO2 was coated on a Poly Vinyl Difluoride (PVDF) membrane (MF) surface using spray coating and dip coating techniques to obtain hybrid functional composite membrane. The characteristics of the synthesized photocatalyst and a functional composite membrane were studied using numerous instruments in terms of physical, chemical and electrical properties. In comparison to the clean PVDF membrane, the TiO2 coated MF membrane was found more effective in removing methylene blue (20%) and E-coli (99%).
Shon, H, Phuntsho, S, Vigneswaran, S, Kandasamy, JK, Nghiem, LD, Kim, G, Kim, JB & Kim, J 2010, 'Preparation of Titanium Dioxide Nanoparticles from Electrocoagulated Sludge using Sacrificial Titanium Electrodes', Environmental Science & Technology, vol. 44, no. 14, pp. 5553-5557.View/Download from: Publisher's site
A comprehensive investigation of electrocoagulation using sacrificial titanium (Ti) electrodes in wastewater was carried out. The effects of specific process variables, such as initial pH, mixing, current density, initial organic loading, and ionic/ electrolyte strength were first optimized to produce recyclable Ti-based sludge. The sludge was incinerated at 600Â°C to produce functional TiO2 photocatalyst. X-ray diffraction analysis revealed that TiO2 produced at optimum electrocoagulation conditions was mostly anatase structure. The specific surface area of the synthesized TiO2 photocatalyst was higher than that of the commercially available and widely used Degussa P-25 TiO2. Furthermore, energy dispersive X-ray and X-ray photoelectron spectroscopy analyses showed that in additional to titanium and oxygen, this photocatalyst is also composed of carbon and phosphorus. These elements were mainly doped as a substitute site for the oxygen atom. Transmission electron microscopy images exhibited sharply edged nanorods, round nanoparticles, and nanotubes with nonuniform shapes showing some structural defects. Photodecomposition of gaseous acetaldehyde by this photocatalyst was also conducted under UV and visible light irradiation to study the photocatalytic properties of the doped TiO2 photocatalyst. While no photocatalytic activity was observed under visible light irradiation, this doped TiO2 photocatalyst exhibited high photocatalytic activity under UV light.
Shon, H, Vigneswaran, S, El Saliby, I, Okour, Y, Kim, IS, Cho, J, Park, HJ, Kim, JB & Kim, JH 2010, 'Hydrogen production affected by Pt concentration on TiO2 produced from the incineration of dye wastewater flocculated sludge using titanium tetrachloride', Desalination and Water Treatment, vol. 15, no. 1-3, pp. 214-221.View/Download from: Publisher's site
TiO2 from the incineration of dye wastewater flocculated sludge using TiCl4 coagulant was produced. Optimal catalyst amount and Pt-loading on TiO2 were studied for the production of H2 by photocatalytic reforming of methanol (6% vol.). On the other hand, BTSE (biologically treated sewage effluent) was flocculated using TiCl4 and produced sludge was incinerated to generate TiO2. TiO2 was loaded with optimum Pt and added to the supernatant in a photocatalytic reactor to test the efficiency of using remaining organics as a âsacrificial reagentâ for photocatalytic hydrogen production. Dissolved organic carbon (DOC) and molecular weight distribution (MWD) were measured for nanofiltration (NF) and TiCl4 flocculation followed by photocatalysis. TiO2 (from the incineration of BTSE flocculated sludge using TiCl4) was produced and loaded with 0.5% Pt. Results showed that the optimum concentration of TiO2 (from dye wastewater) for H2 production was 0.3 g/L, while the optimum amount of Pt was 0.5%. DOC and MWD removal was similar for the flocculation of BTSE followed by photocatalytic reaction and the NF process. Remaining organic compounds after flocculation could not be used as sacrificial reagent to induce H2 production. Further investigations on studying the UV intensity and/or identifying organic/inorganic scavengers to inhibit H2 production are underway.
Shon, HK, Vigneswaran, S, El Saliby, I, Okour, Y, Kim, IS, Cho, J, Park, HJ, Kim, JB & Kim, J-H 2010, 'Hydrogen production affected by Pt concentration on TiO2 produced from the incineration of dye wastewater flocculated sludge using titanium tetrachloride', DESALINATION AND WATER TREATMENT, vol. 15, no. 1-3, pp. 214-221.View/Download from: Publisher's site
Kim, SH, Shon, H & Ngo, H 2010, 'Adsorption Characteristics Of Antibiotics Trimethoprim On Powdered And Granular Activated Carbon', Journal of Industrial and Engineering Chemistry, vol. 16, no. 3, pp. 344-349.View/Download from: Publisher's site
The adsorption characteristics of trimethoprim (TMP) onto powdered activated carbon (PAC) and granular activated carbon (GAC) were studied. The adsorption isotherms could be plotted using the Langmuir, Freundlich and Toth models with a reasonable degree
Ren, X, Shon, H, Jang, N, Lee, YG, Bae, M, lee, J, Cho, K & Kim, IS 2010, 'Novel membrane bioreactor (MBR) coupled with a nonwoven fabric filter for household wastewater treatment', Water Research, vol. 44, no. 3, pp. 751-760.View/Download from: Publisher's site
Conventional and modified membrane bioreactors (MBRs) are increasingly used in small-scale wastewater treatment. However, their widespread applications are hindered by their relatively high cost and operational complexity. In this study, we investigate a new concept of wastewater treatment using a nonwoven fabric filter bag (NFFB) as the membrane bioreactor. Activated sludge is charged in the nonwoven fabric filter bag and membrane filtration via the fabric is achieved under gravity flow without a suction pump. This study found that the biofilm layer formed inside the NFFB achieved 10 mg/L of suspended solids in the permeate within 20 min of initial operation. The dynamic biofilter layer showed good filterability and the specific membrane resistance consisted of 0.3â1.9 Ã 1012 m/kg. Due to the low F/M ratio (0.04â0.10 kg BOD5/m3/d) and the resultant low sludge yield, the reactor was operated without forming excess sludge. Although the reactor provided aerobic conditions, denitrification occurred in the biofilm layer to recover the alkalinity, thereby eliminating the need to supplement the alkalinity. This study indicates that the NFFB system provides a high potential of effective wastewater treatment with simple operation at reduced cost, and hence offer an attractive solution for widespread use in rural and sparsely populated areas.
Kwon, B, Shon, H & Cho, J 2009, 'Characterizations of Colloidal Organic Matter Isolated from Surface Water', Separation Science and Technology, vol. 44, no. 13, pp. 3224-3238.View/Download from: Publisher's site
This study investigated the effect of the molecular weight cut-off (MWCO) of a dialysis membrane for the isolation of colloidal organic matter (COM) from surface water. Various dialysis membranes with different MWCO were used for the isolation of COM from Cebron reservoir natural organic matter (CRNOM). The COM included mainly amino sugars (3040%) and polysaccharides (3040%), with 23 of fatty acids over aromatic acids (F=A ratio), indicating that the COM were derived from microbial substances. As all the COM constituents were found to have similar characteristics, the MWCO of the dialysis membrane was not found to influence the COM characteristics.
Kwon, B, Shon, H & Cho, J 2009, 'Investigating the relationship between model organic compounds and ultrafiltration membrane fouling', Desalination and Water Treatment, vol. 8, no. 1-3, pp. 177-187.View/Download from: Publisher's site
The aims of this study were to investigate the fouling mechanisms of model organic compounds (MOCs) on two ultrafiltration membranes [composite regenerated cellulose (YM100) and polyethersulfone (PES)] and the relationship between fouling and membrane characteristics, flux decline, and the streaming potential (SP). Two alginic acids (polymer and dimmer, AA), abietic acid (AbA), colominic acid (CA), and N-acetylneuraminic acid (NA) were selected as MOCs to test their membrane fouling potential through flux decline and SP. The fouling caused by the two AAs, which contained many polysaccharides, was the highest among MOCs, but this fouling was external (solute deposition on the membrane surface) and reversible as polysaccharides did not strongly adsorb onto the YM100 and PES membranes. CA also caused external fouling of the two membranes; however, AbA caused internal (solute adsorption on the pores wall of membrane) and irreversible fouling of the PES membrane. NA, which contained amino sugars, exhibited very low fouling of both membranes. The hydrophilic YM100 membrane experienced less fouling than the hydrophobic PES membrane with all MOCs. The measurement of the SP using a modified dead-end filtration cell was employed to evaluate the flux decline due to MOCs.
Nisola, G, Cho, E, Shon, H, Tian, D, Chun, D, Gwon, E & Chung, W 2009, 'Cell Immobilised FOG-Trap System for Fat, Oil, and Grease Removal from Restaurant Wastewater', Journal Of Environmental Engineering-asce, vol. 135, no. 9, pp. 876-884.View/Download from: Publisher's site
Cell immobilized lipase-producing bacteria on three different matrices were incorporated in a fat-, oil-, and grease (FOG) trap system for restaurant wastewater treatment. During a 16-day laboratory-scale experiment for the treatment of synthetic FOG wastewater containing soybean oil, no significant difference (two-tailed t test at 95% confidence interval) in the FOG removal between two systems was observed at FOG influent < 1,000 mg/L. However, the typical trap showed lower FOG removal efficiency than the matrix-based system when the influent FOG concentration was increased to >= 5,000 mg/L. In addition, the matrix-based trap system was able to sustain a stable high FOG removal, with < 100 mg/L effluent, even at 10,000 mg/L influent FOG. Based on FOG heights measured and mass balance calculations, 97.4 and 99.5% of the total FOG load for 16 days were removed in a typical trap and matrix-based system, respectively. About 93.6% of the removal in the matrix-based was accounted to biodegradation. The 30-day full-scale operations demonstrated a distinguishably better performance in the matrix-based system (92.7 +/- 9.06% of 1,044.8 +/- 537.27 mg FOG/L) than in the typical trap system (74.6 +/- 27.13% of 463.4 +/- 296.87 mg FOG/L) for the treatment of barbeque restaurant wastewater. Similarly, matrix-based system revealed higher chemical oxygen demand removal (85.9 +/- 11.99%) than the typical trap system (60.4 +/- 31.26%). Characterizations of the influent, emulsified, adsorbed and effluent FOG indicated that straight saturated fatty acids constituted the cause of clogging problems in the FOG-trap and piping system.
Okour, Y, Shon, H & El Saliby, I 2009, 'Characterisation of titanium tetrachloride and titanium sulfate flocculation in wastewater treatment', Water Science and Technology, vol. 59, no. 12, pp. 2463-2473.View/Download from: Publisher's site
Flocculation with titanium tetrachloride (TiCl4) and titanium sulfate (Ti(SO4)2) was investigated in terms of different coagulant doses, pH, turbidity, dissolved organic carbon (DOC), UV-254, colour, zeta potential, particle size and molecular weight distribution. The two coagulants were compared with the commonly used coagulants such as ferric chloride (FeCl3) and aluminium sulfate (Al2(SO4)3). Titanium tetrachloride showed the highest turbidity removal, while titanium sulfate showed the highest reduction of UV-254 and colour at all pH values. The four coagulants were found to have similar organic removal up to 6067% and resulted in similar organic removal in terms of various MW ranges. The decantability of the settled flocs was very high for titanium tetrachloride, titanium sulfate and ferric chloride compared with aluminium sulfate. The dominating coagulation mechanisms for titanium tetrachloride and titanium sulfate are still to be studied, since different precipitation reactions might take place at different pH even without flocculant addition. Titanium tetrachloride and titanium sulfate were found as effective new coagulants in wastewater treatment not only in terms of organic matter removal, but also in sludge reduction through the production of titanium dioxide.
Shon, H, Cho, DL, Na, SH, Kim, JK, Park, HJ & Kim, JK 2009, 'Development of a novel method to prepare Fe- and Al-doped TiO2 from wastewater', Journal of Industrial and Engineering Chemistry, vol. 15, no. 4, pp. 476-482.View/Download from: Publisher's site
A simple and novel method to synthesize iron and aluminium-doped titanium dioxide (TiO2) was investigated. Titanium tetrachloride (TiCl4) was used as a coagulant to remove organic matter from wastewater. The settled floc (sludge) was dewatered and incinerated at 600 degrees C after TiCl4 flocculation. The resultant by-product from the waste sludge was valuable TiO2. TiCl4 coagulant was added with FeCl3 and Al-2(SO4)(3) coagulants to dope iron and aluminium on TiO2 in a flocculation process. The effect of iron and aluminium on TiO2 was investigated in terms of scanning electron microscopy/energy dispersive Xray (SEM/EDX), X-ray diffraction (XRD), optical absorbance and photocatalytic activity. The majority of Fe/TiO2 and Al/TiO2 particles were found to be less than 1 mu m size formed by 0.1 mu m agglomerates using SEM analysis. Fe/TiO2 included Ti, O, C, P and Fe elements and Al/TiO2 consisted of Ti, O, C, P and Al elements as confirmed by EDX results. Remaining organic carbon from the settled organic matter was the source of C atom in TiO2 whereas the P atom in TiO2 came from phosphorus nutrient present in wastewater. The majority of acetaldehyde with Fe/TiO2 and AI/TiO2 was significantly removed under UV irradiation within 60 min. However, at higher iron concentration, acetaldehyde removal decreased by almost 50%. Under visible light irradiation, the photo-decomposition of acetaldehyde using the Fe/TiO2 and Al/TiO2 was marginal.
Shon, H, Okour, Y, El Saliby, I, Park, J, Cho, DL, Kim, JB, Park, HJ & Kim, JH 2009, 'Preparation and Characterisation of Titanium dioxide Produced from Ti-salt Flocculated Sludge in Water Treatment', Journal of the Korean Industrial and Engineering Chemistry, vol. 20, no. 3, pp. 241-250.View/Download from: Publisher's site
In this study, titanium (Ti), ferric (Fe) and aluminum (Al) salt flocculants were compared for their efficiency in treating wastewater collected from Sydney Olympic Park wastewater treatment plant by following the jar test procedure. Produced sludge from Ti-salt flocculation was dried and titanium dioxide (TiO2) nanoparticles were generated after the incineration of sludge produced from the Ti-salt flocculation of wastewater. Later on, titanate nanotubes were synthesized after TiO2 nanoparticles were hydrothermally treated with 10 N NaOH solution at 130 °C for 24 h. Titanate nanotubes were either acid or deionised water-washed, while thiourea-doping was employed to produce visible light-responsive nanotubes. Wastewater flocculation using Ti-salt was found to be as efficient as Fe and Al flocculation in terms of turbidity and DOC removal. XRD results showed that the anatase structure was predominant for TiO2 nanoparticles, while thiourea-doped titanate nanotubes only indicated anatase structure with an increased crystallinity after being crystallized at 600 °C. The photocatalytic activity of all photocatalysts was evaluated using the photooxidation of acetaldehyde. Thiourea-doped nanotubes showed a greater photocatalytic activity than as-prepared TiO2 nanoparticles, deionised water-washed, acid-washed titanate nanotubes and P25 under UV and visible light irradiation.
Yun, Y, Shon, H & Yoon, S 2009, 'Preparation and characterisation of molecularly imprinted polymers for the selective separation of 2,4-dichlorophenoxyacetic acid', Journal Of Materials Science, vol. 44, no. 22, pp. 6206-6211.View/Download from: Publisher's site
As a method of preparing ligand-selective cavities in a synthetic polymer matrix, molecular imprinting technique has been attracting significant interest from a large number of areas in chemistry and analytical sciences. In this study, molecularly imprinted polymers (MIPs) were prepared with styrene, 4-vinylpyridine (4-VPy), and divinylbenzene (DVB) for the separation of hazardous 2,4-dichlorophenoxyacetic acid (2,4-D), and the selectivity of MIPs as adsorbed 2,4-D and structurally similar materials was evaluated. The template was removed through the swelling process of toluene/ethanol, and the removal ratio was about 95-99%, respectively. MIPs synthesized in this study had good adsorption selectivity in the presence of other materials, although there was a difference of adsorption quantities (uptake) in the functional monomer (4-VPy contents) and the cross-linker (DVB contents). The results exhibit that the selectivity of MIPs was improved significantly by controlling the cross-linker. We expect that molecular imprinting technique will serve as a novel method for selective separation of specific materials in various fields, especially in the fields of environment and pharmaceutics.
Aryal, R, Lebegue, J, Shon, H, Vigneswaran, S, Kandasamy, JK & Grasmick, A 2009, 'Temporal variation of foulant characteristics in membrane bioreactor', Desalination and Water Treatment, vol. 6, no. 1-3, pp. 69-73.
Many studies have been performed to analyse the influence of compounds present in different fractions of the membrane foulants. The aim of this study was to reveal the changing chemistry of compounds present in membrane foulant with the evolution of time. Membrane fouling in a side stream membrane bioreactor (MBR) reactor was investigated. Constant flux filtration was employed in an MBR operation. Air bubbles were injected at 2 m3 h1 m2 for six different durations (2, 4, 6, 9, 15 and 20 days) of MBR operation. The foulant on the membrane surface was extracted using NaOH solution (5%) and analysed using fluorescent spectroscopy. The spectra showed the changing chemistry of foulant with the evolution of time. It showed low molecular weight substances such as amino acids and small aromatic proteins were dominant in the foulant at the beginning of the experiment but its concentration decreased with time. On the other hand BOD5 type substances concentration increased with time from the beginning of the experiment up to 9 days and there after decreased. The concentration of larger molecular weight soluble microbial by-products increased with evolution of time. Air bubbles at two aeration rate of 1m3 h1m2 and 2 m3 h1 m2 were also injected from the bottom of the membrane tanks to produce shear stresses on the membrane surface during 5 days of MBR operation to compare the effect of aeration in fouling propensity.
Chinu, KJ, Johir, MH, Vigneswaran, S, Shon, H & Kandasamy, JK 2009, 'Biofilter as pretreatment to membrane based desalination: Evaluation in terms of fouling index', Desalination, vol. 247, no. 1-3, pp. 77-84.View/Download from: Publisher's site
The removal of particulate matter and dissolved organic matter from seawater by the use of biofiltration was investigated. Granular activated carbon (GAC) and anthracite were used as biofilter media at two different filtration velocities. Filtrate quality was measured in terms of silt density index (SDI), modified fouling index (MFI) and turbidity removal. Reverse osmosis (RO) was used as a post-treatment. Both biofilters demonstrated similar fouling reduction behavior in terms of SDI and MFI. Fouling potential in terms of MFI values decreased to 10 s/L2 within the first 10â15 days of operation and kept constant up to the remaining experimental period of 55 days of operation for both GAC and anthracite biofilter. The filtrate turbidity was steady after 10 days and remained low at a value of 0.2â0.3 NTU and 0.28â0.31 NTU for anthracite and GAC biofilter, respectively. Furthermore, the headloss development was low and within 20 cm for biofilter operated at a low velocity of 5 m/h. A post-treatment of reverse osmosis after a pretreatment of GAC and anthracite biofilters showed a reduction in normalized flux decline (J/J0) from 0.22 to 0.12 and 0.35 to 0.21 during the first 20 h, respectively. The RO flux for seawater declined at a faster rate and continued even after 3 days when no pretreatment was provided.
El Saliby, I, Okour, Y, Shon, H, Vigneswaran, S, Kandasamy, JK & Kim, JH 2009, 'Detailed Investigation on the Effect of Washing TiO2 Prepared from Ti-salts Flocculated Wastewater Sludge', Journal of Advanced Oxidation Technologies, vol. 12, no. 2, pp. 194-201.
In this study, the effect of washing TiO2 produced from flocculated sludge was investigated. Produced TiO2 was washed with HCl, NaOH and Milli-Q-water and the washed TiO2 was then characterized in terms of X-ray diffraction imaging, scanning electron microscope/energy dispersive using X-ray analysis and surface area. Washed TiO2 was tested for adsorption and photocatalytic oxidation of acetaldehyde, and the decomposition of organics from synthetic wastewater (SWW) in terms of total organic carbon (TOC) and absorbance at UV-254. Results revealed that the anatase structure was dominant and TiO2 was mainly doped with C atoms. The surface area of TiO2 generated form TiCl4 flocculation was found to be twice larger than the TiO2 generated from Ti(SO4)2 flocculation. Acid and base washings of TiO2 improved its photocatalytic ability in decomposing acetaldehyde under UV-irradiation. Similarly, acid, base and Milli-Q water washings of TiO2 were better in reducing TOC and humic acids from SWW.
Johir, MH, Chinu, KJ, Vigneswaran, S & Shon, H 2009, 'In-line flocculation - filtration as pre-treatment to reverse osmosis desalination', Desalination, vol. 247, no. 1-3, pp. 85-93.View/Download from: Publisher's site
In this paper the performance of single and dual media filters with in-line flocculation have been examined as pretreatment to seawater reverse osmosis (SWRO). A comparison of filter performance was made between single medium filter (80 cm) consisting of sand or anthracite, and dual media filter consisting of sand (40 cm at the bottom) and anthracite (40 cm on top). Short term (6 hours) experiments were conducted with in-line coagulation followed by direct filtration. Filtration velocities of 5 m/h and 10 m/h were used. The performances of these filters were assessed in terms of turbidity removal, head loss build-up, and organic compound removal in terms of molecular weight distribution (MWD). The efficiency of the filter as pretreatment was evaluated in terms of silt density index (SDI) and modified fouling index (MFI). It was found that the turbidity removal was high and all the filters produced more or less same quality water. There was a slower buildup of head loss for coarser filter medium. A post treatment of reverse osmosis after an inline-flocculation-dual media filtration showed lower normalized flux decline (J/J0) (0.35 to 0.22 during the first 20 hours operation) while, seawater without any pretreatment showed steeper flux decline (0.18 to 0.11 at first 20 hours operation) in RO.
Lee, B, Kim, SH, Shon, H, Vigneswaran, S, Kim, SH, Cho, J, Kim, I, Choi, K, Kim, JK, Park, HJ & Kim, JK 2009, 'Aquatic toxicity evaluation of TiO2 nanoparticle produced from sludge of TiCl4 flocculation of wastewater and seawater', Journal of nanoparticle Research, vol. 11, no. 8, pp. 2087-2096.View/Download from: Publisher's site
Flocculation using titanium tetrachloride (TiCl4) as a coagulant is an efficient and economical application because the flocculated sludge can be recycled to produce a valuable byproduct, namely titanium dioxide (TiO2) nanoparticles. However, toxicity of TiCl4 has not yet been assessed while it is used in water treatment. The aquatic toxicity of TiCl4 flocculation process was investigated to assess the environmental safety of the coagulant. D. magna and V. fischeri bioassays were carried out to evaluate the supernatant toxicity after TiCl4 flocculation. Artificial wastewater, biologically treated sewage effluent, and seawater were used to study the toxicity of TiCl4 flocculation. Results showed that supernatant toxicity was very low when TiCl4 flocculation was conducted (no observed effect concentration = 100 mg/L and lowest observed effect concentration = 150 mg/L exposed to D. magna and V. fischeri, respectively). Similarly, TiO2 nanoparticles recovered from wastewater and seawater flocculated sludge were also found to have low toxicity. The regenerated TiO2 nanoparticles indicated low toxicity values when compared to the commercial-TiO2 nanoparticle, P-25.
Lee, J, Johir, J, Chinu, KJ, Shon, H, Vigneswaran, S, Kandasamy, JK, Kim, CW & Shaw, K 2009, 'Hybrid filtration method for pre-treatment of seawater reverse osmosis (SWRO)', Desalination, vol. 247, no. 1-3, pp. 15-24.View/Download from: Publisher's site
Hybrid processes combining fi bre fi lter with deep bed fi ltration process such as (i) fi bre fi lter and sand fi lter, (ii) fi bre fi lter and anthracite and (iii) fi bre fi lter and dual media fi lter were investigated as pre- treatments to SWRO. Seawater was drawn from Chowder Bay, Sydney. The eff ect of diff erent pretreatment hybrid systems was investigated in terms of silt density index (SDI10), modifi ed fouling index (MFI), headloss across the fi lters and reduction in turbidity and dissolved organic carbon (DOC). The in-line fl occulation in fi bre fi lter improved the performance of the pretreatment hybrid system as measured by the MFI, SDI10, headloss, turbidity and DOC removal. The lowest SDI10 and MFI were found with a fi bre fi lter operated at a fi ltration velocity of 40 m/h followed by dual media fi lter operated at a fi ltration velocity of 5 m/h. The lowest headloss and turbidity was found with a fi bre fi lter operated at a fi ltration velocity of 40 m/hr followed by anthracite operated at a fi ltration velocity of 5 m/h. This system also gave an effl uent with the lowest DOC of 0.64 mg/L corresponding to a removal effi ciency of about 70%.
Mohammed Abdul, J, Chinu, KJ, Shon, H & Vigneswaran, S 2009, 'Effect of pre-treatment on fouling propensity of feed as depicted by the modified fouling index (MFI) and cross-flow sampler-modified fouling index (CFS-MFI)', Desalination, vol. 238, no. 1-3, pp. 98-108.View/Download from: Publisher's site
The effectiveness of different pretreatment on the fouling propensity of the feed was studied using synthetic wastewater. The fouling potential of the feed was characterized by the standard modified fouling index (MFI) and cross-flow sampler modified fouling index (CFSMFI). In CFSMFI, a cross-flow sampler was used to simulate the condition of a cross-flow filtration. The results indicated that the pretreatment such as flocculation with an optimum dose of 68 mg/l FeCl3 substantially reduced the fouling propensity of the feed. The standard MFI of flocculated wastewater was reduced by around 99% compared to that of the untreated wastewater. Similarly, the adsorption with powdered activated carbon (PAC) of 1 g/l reduced the standard MFI value to more than 99% compared to that of the untreated wastewater. The CFSMFI values were lower than the standard MFI values for both treated and untreated wastewater, suggesting that the standard MFI was overestimated. The overestimation of the standard MFI compared to that of the CFSMFI value was more than 99%. The effect of molecular weight distribution (MWD) of the foulants in the wastewater on the fouling propensity of the feed was investigated. The MWD was correlated with the MFI and CFSMFI indices. It yielded useful insights in understanding the effect of MW on MFI and CFSMFI and fouling propensity of the feed.
Mohammed Abdul, J, Vigneswaran, S, Shon, H, Areerachakul, N & Kandasamy, JK 2009, 'Comparison of granular activated carbon bio-sorption and advanced oxidation processes in the treatment of leachate effluent', Korean Journal Of Chemical Engineering, vol. 26, no. 3, pp. 724-730.View/Download from: Publisher's site
Nguyen, V, Vigneswaran, S, Ngo, H, Shon, H & Kandasamy, JK 2009, 'Arsenic removal by a membrane hybrid filtration system', Desalination, vol. 236, no. 1-3, pp. 363-369.View/Download from: Publisher's site
Arsenic is a toxic semi-metallic element that can be fatal to human health. Membrane filtration can remove a number of contaminants from water, including arsenic. Removal of arsenic by membrane filtration is highly dependent on the species of arsenic and the properties of the membrane. The performance of the nanofilter is better for removing As(V) than As(III). About 57% of As(III) and 81% of As(V) was removed from 500 mg/L arsenic solutions by nanofiltration (NTR729HF, Nitto Denko Corp., Japan) of 700 molecular weight (MW) cutoff. The removal efficiency of microfiltration (MF) was much lower than that of nanofiltration (NF) due to its larger pore size. By comparison only 37% of As(III) and 40% of As(V) were removed by microfiltration (PVA membrane, Pure-Envitech, Korea). However, the removal efficiency of microfiltration was increased dramatically when a small amount of nanoscale zero valent iron (nZVI) was added. The removal efficiency by MF increased up to 90% with As(V) and 84% with As(III) when an amount of 0.1 g/L of nZVI was added into the arsenic solution.
Okour, Y, El Saliby, I, Shon, H, Vigneswaran, S, Kim, JH, Cho, J & Kim, IS 2009, 'Recovery of sludge produced from Ti-salt flocculation as pretreatment to seawater reverse osmosis', Desalination, vol. 247, no. 1-3, pp. 53-63.View/Download from: Publisher's site
In this study, titanium tetrachloride (TiCl4), titanium sulfate (Ti(SO4)2) and ferric chloride (FeCl3) flocculation as a pretreatment to seawater reverse osmosis (SWRO) were investigated. Their ability to remove turbidity, seawater organic matter (SWOM) and controlling the feed water quality of SWRO was evaluated. Flux decline of SWRO and membrane autopsy were studied. Titanium dioxide (TiO2) produced from sludge after Ti-salt fl occulation was characterized in terms of particle structure and photocatalytic activity. A hybrid system of fl occulation followed by granular activated carbon (GAC) filtration was employed to remove the suspended micro-flocs after diff erent fl occulations. The optimum dose of 10 mg/L TiCl4 and FeCl3 were used. The turbidity removal for the three coagulants was marginal at different doses at pH 6 and 8. Flocculation followed by GAC fi ltration signifi cantly reduced the turbidity values from 1.5 NTU to about 0.35 NTU using TiCl4 and 0.40 using FeCl3. Silt density index (SDI15) was also decreased from 5.0 to 4.2 and 4.7, respectively. Removal of dissolved organic carbon (DOC), colour and UV absorbance after TiCl4 and FeCl3 flocculation followed by GAC fi ltration was found to be eff ective and similar. TiO2 produced from sludge showed very high photocatalytic activity under UV-irradiation. Acetaldehyde was completely removed after 45 min photocatalytic reaction
Shon, H, Kim, SH, Vigneswaran, S, Ben Aim, RM, Lee, S & Cho, J 2009, 'Physicochemical Pretreatment Of Seawater: Fouling Reduction And Membrane Characterisation', Desalination, vol. 238, no. 1-3, pp. 10-21.View/Download from: Publisher's site
The pretreatment of raw seawater is necessary to minimize the organic fouling of seawater reverse osmosis (SWRO) membranes. To predict the membrane fouling of the pretreated seawater, the modified fouling index (MFI) with ultrafiltration (UF) was investigated in terms of molecular weight distribution (MWD) and membrane characterization. The study was conducted with seawater drawn from Collioure, France. The concentration of total dissolved solids was 32,760 mg/L. The molecular weight (MW) of the initial seawater organic matter (SWOM) ranged from about 14160 Da to 280 Da. FeCl3 flocculation removed the majority of SWOM, while PAC adsorption could not remove the lowest MW fraction of organic matter (1110, 750 and 280 Da). The UF membranes with 30 kDa and 100 kDa MW cut-off removed the majority of of organic matter corresponding to the peaks 14,160 Da and 6560 Da in MWD. The MFI values obtained when using UF membranes of 30 kDa and 100 kDa with MF pretreatment were 19,700 s/L2 and 31,000 s/L2, respectively. The MFI values after pretreatments of FeCl3 flocculation and PAC adsorption significantly decreased to 6900 s/L2 and 6700 for 30 kDa UF and to 2300 s/L2 and 2500 s/L2 for 100 kDa UF, respectively. Some relation does exist for both membranes between the MFIUF values and Spb values obtained during the first peiod of filtration (pore blocking). The pore blocking zone significantly decreased after flocculation and adsorption pretreatment. This suggests that the pore blocking can be used as an indicator to predict membrane propensity. The detailed membrane characterization on the clean and fouled membrane surface after MFIUF experiments was made in terms of contact angle, zeta potential, functional group and microscopy.
Shon, H, Puntsho, S, Chon, K, Aryal, R, Vigneswaran, S, Kim, IS & Cho, J 2009, 'A study on the influence of ionic strength on the elution behaviour of membrane organic foulant using advanced separation tools', Desalination and Water Treatment, vol. 11, no. 1-3, pp. 38-45.View/Download from: Publisher's site
Although membrane technology has become a reliable and viable alternative for water and wastewater treatment, membrane fouling is a serious challenge. In this case study, we report application of different techniques to extract foulant from the hollow fi bre membrane and characterize the foulant into various components of organic, inorganic and different fractions. The organic foulant was subjected to high-pressure size exclusion chromatography (HPSEC) and fl ow fi eld-fl ow fractionation (FlFFF) analysis to study the infl uence of ionic strength on its elution behaviour using NaCl and CaCl2 as carrier solutions. It was observed that an increase in ionic strength delayed the elution time of both the organic foulant and the Na-salt of Polysterene sulphone (PSS) with HPSEC. However, no such effect was observed with FlFFF analysis. Such study is signifi cant because the characteristics of the membrane organic foulant are believed to be infl uenced by the carrier ionic conditions and pH and, therefore their subsequent interaction with the membrane and membrane fouling process. However with FlFFF, whether the infl uence of carrier ionic strength is limited to certain type of ionic carriers or certain groups of natural organic matter is a scope for further research.
Shon, H, Vigneswaran, S, Kandasamy, JK, Kim, JB, Park, HJ, Choi, S & Kim, JH 2009, 'Preparation of titanium oxide, iron oxide, and aluminium oxide from sludge generated from Ti-salt, Fe-salt and Al-salt flocculation of wastewater', Journal of Industrial and Engineering Chemistry, vol. 15, no. 5, pp. 719-723.View/Download from: Publisher's site
In this study, the settled floc (sludge) produced by aluminum sulfate (Al2(SO4)3), ferric chloride (FeCl3) and titanium tetrachloride (TiCl4) flocculation was recycled with a novel flocculation process, which has a significant potential to the lower cost of waste disposal, protect the environment and public health and yield economically useful by-products. Three coagulants removed 70% of organic matter in synthetic wastewater. The settled floc was incinerated in the range from 100 8C to 1000 8C. Alumina (Al2O3), hematite (Fe2O3), titanium oxide (TiO2) which are the most widely used metal oxides were produced from the wastewater sludge generated by the flocculation in wastewater with Al2(SO4)3, FeCl3 and TiCl4, respectively. TiO2 particles produced from the sludge consisted of the large amount of nano size particles. Hematite (Fe2O3) and grattarolaite (Fe3 (PO4)O3 or Fe3PO7) included the majority of micro size (40%) particles. Alumina (Al2O3) also consisted of micro size (40%). Due to TiO2 usefulness of the application, detailed characterisation of TiO2 after calcination at different temperatures were investigated in terms of X-ray diffraction, energy dispersive X-ray, surface area and photoactivity.
Australia is the driest continent on earth and despite this the installed desalination capacity is still around 1% of the total world's desalination capacity. This paper reviews the main seawater issues considered in every desalination projectâthe history, the present situation and the future of desalination in Australia, the suitability of applying reverse osmosis (RO) and the project details of two desalination plants (Sydney and Perth). Ocean currents, seawater temperature and salinity are signifi cant indicators in the assessment of the feasibility of desalination as they aff ect the production costs, the maintenance frequency and the quality of the product water. Seawater reverse osmosis (SWRO) is the only type of desalination technology currently used or proposed for future large-scale desalination plants in Australia. Every capital city except Darwin has considered building at least one desalination plant as a means of providing water security after several years of unprecedented drought that has signifi cantly reduced dam storage levels. Perth was the fi rst major city to use desalinated water for drinking water supply and by early 2009 Sydney will be the second city. Thirteen other large-scale SWRO plants are being planned or proposed at several locations for the purpose of supplying drinking water.
Shon, H, Vigneswaran, S, Kandasamy, JK, Zareie, HM, Kim, JB, Cho, DL & Kim, JH 2009, 'Preparation and Characterisation of Titanium Dioxide (TiO2) from Sludge produced by TiCl4 Flocculation with FeCl3, Al2(SO4)3 and Ca(OH)2 Coagulant Aids in Wastewater', Separation Science and Technology, vol. 44, no. 7, pp. 1525-1543.View/Download from: Publisher's site
In this study, TiCl4 coagulant together with coagulant aids such as FeCl3, Al2(SO4)3, and Ca(OH)2 were investigated to improve the photoactivity of titanium dioxide (TiO2) produced from sludge and to increase the resulting low pH value. After TiCl4 flocculation with three coagulant aids, the settled floc (sludge) was incinerated at 600Â°C to produce TiO2 doped with Fe, Al, and Ca elements. Fe-, Al-, and Ca-doped TiO2 was characterized in terms of structural, chemical, and photo-electronic properties. All the coagulant aids used together with Ti-salt flocculation effectively increased the pH values. The surface area of TiO2-WO (without any coagulant aids), Fe/TiO2, Al/TiO2, and Ca/TiO2 was 122 m2/g, 77 m2/g, 136 m2/g and 116 m2/g, respectively. The TiO2-WO, Fe/TiO2, Al/TiO2, and Ca/TiO2 was found to be of anatase phase. The XRD pattern on the Fe/TiO2 included an additional peak of hematite (Î±-Fe2O3). The majority of gaseous acetaldehyde with TiO2-WO and Ca/TiO2 for photocatalytic activity was completely removed within 40 minutes under UV irradiation.
Shon, H, Vigneswaran, S, Zareie, HM, Ben Aim, R, Lee, E, lee, J, Cho, J & Kim, IS 2009, 'Physico-chemical pretreatment to Seawater Reverse Osmosis (SWRO): Organic Characterization and Membrane Autopsy', Desalination, vol. 236, no. 1 - 3, pp. 282-290.View/Download from: Publisher's site
In this study, different pretreatment methods such as microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), powdered activated carbon (PAC) adsorption and ferric chloride (FeCl3) flocculation were evaluated in terms of their capability in removing seawater organic matter (SWOM) and the characteristics of the foulants on the seawater reverse osmosis (SWRO) membranes. A detailed experiment with a crossflow SWRO filtration unit was conducted with SR membrane (MWCO 100 Da) at 60 bar with seawater (conductivity = 48.9 mS/cm) drawn from south-western Korea. The SWOM removal by UF, NF, PAC adsorption and FeCl3 flocculation was 20.3, 28.9, 46 and 23.3%, respectively. SWOM used in this study predominantly consisted of small size organic matter (<1000 Da). A large amount of the hydrophobic fraction present in SWOM was removed by PAC adsorption. The SDI5min significantly decreased from 12.7 (without any pretreatment) to 3.2 (MF), 1.3 (UF), 1.0 (NF) and 4.4 (PAC adsorption). RO filtration of seawater with and without pretreatment showed significant flux decline (normalized flux decline (J/J0) = 0.17 ± 0.02) within 20-h operation. The elemental analyses made on the RO surface after direct RO filtration showed that the relative fraction of the carbon decreased, while sodium (Na), magnesium (Mg), chlorine (Cl) and iron (Fe) elements were found in the foulants extracted from the fouled membrane surface. The average roughness of the clean membrane surface was 41.5 nm. After MF and UF pretreatment, the roughness slightly increased to 54.8 and 55.6 nm, respectively. On the other hand, without any pretreatment, with PAC adsorption and with FeCl3 flocculation, the roughness increased up to 69.7, 66.4 and 110 nm, respectively. It can be concluded that the pretreatment by MF and UF could relatively preserve the RO membrane surface.
Lim, GT, Kim, KH, Kim, KS, Li, H, Song, S, Shon, H & Cho, DL 2008, 'A study on the dry cleaning of aluminium surfaces by low temperature plasma process', Journal of the Korean Industrial and Engineering Chemistry, vol. 19, no. 6, pp. 640-644.
Lubricating oil on aluminium surfaces was cleaned by a low temperature plasma process. Oxygen plasma mixed with argon was used, and process parameters were the mixing ratio of argon in oxygen, discharge power, and negative DC potential. The aluminium surfaces were analyzed with FTIR and EDX after the cleaning. It was found that almost all of the oil was eliminated in 20 min. if the oil was pure. Elimination efficiency was highly dependent on operational conditions of the process. The highest efficiency was obtained when treated at 300 W with oxygen plasma mixed with 30% argon applying negative potential more than -500 V on the aluminium surfaces. However, efficiency higher that 60% cannot be obtained at any condition if the oil contained inorganic materials.
Shon, H, Phuntsho, S, Okour, Y, Cho, DL, KK, S, Li, JH, Na, SH, Kim, JB & Kim, JH 2008, 'Visible light responsive titanium dioxide (TiO2)', Journal of the Korean Industrial and Engineering Chemistry, vol. 19, no. 1, pp. 1-16.View/Download from: Publisher's site
Titanium dioxide (TiO2) is one of the most researched semiconductor oxides that has revolutionised technologies in the field of environmental purification and energy generation. It has found extensive applications in heterogenous photocatalysis for removing organic pollutants from air and water and also in hydrogen production from photocatalytic water-splitting. Its use is popular because of its low cost, low toxicity, high chemical and thermal stability. But one of the critical limitations of TiO2 as photocatalyst is its poor response to visible light. Several attempts have been made to modify the surface and electronic structures of TiO2 to enhance its activity in the visible light region such as noble metal deposition, metal ion loading, cationic and anionic doping and sensitisation. Most of the results improved photocatalytic performance under visible light irradiation. This paper attempts to review and update some of the information on the TiO2 photocatalytic technology and its accomplishment towards visible light region.
Song, SJ, Kim, KS, Kim, KH, Li, HJ, Cho, DL, Kim, JB, Park, HJ, Shon, H & Kim, JH 2008, 'Fabrication of TiO2 impregnated stainless steel fiber photocatalyts and evaluation of photocatalytic activity', Journal of the Korean Industrial and Engineering Chemistry, vol. 19, no. 6, pp. 674-679.
TiO2 impregnated stainless steel fiber photocatalysts (TiO 2/SSF) were fabricated to overcome inherent problems of powdery TiO2 photocatalysts in water treatment. Adhesion strength of the impregnated TiO2 was examined using an ultrasonic-cleaner. Photocatalytic activity was evaluated through decomposition experiment of methylene blue and formic acid. Bactericidal efficiency was evaluated through sterilization experiment of E. Coli and Vibrio Vulnificus. Adhesion strength of the impregnated TiO2 was so high that more than 95% was left over even after the treatment in an ultrasonic-cleaner for 30 min. Methylene blue and formic acid were decomposed as much as 60% and 38% of the initial concentration and more than 99.9% of E. Coli and Vibrio Vulnificus were killed after 1 hour exposure to the prepared photocatalyst under UV irradiation. In the case of decomposition of formic acid, decomposition ratio increased if oxidants were added. Especially the decomposition ratio increased as high as 80% when hydrogen peroxide was added as an oxidant.
Kim, S, Ngo, H, Shon, H & Vigneswaran, S 2008, 'Adsorption and Photocatalysis Kinetics of Herbicide onto Titanium Oxide and Powdered Activated Carbon', Separation and Purification Technology, vol. 58, no. 3, pp. 335-342.View/Download from: Publisher's site
The adsorption and photocatalysis kinetics of metsulfuron-methyl (MM) onto titanium oxide (TiO2) and powdered activated carbon (PAC) were studied at varying adsorbent amount and MM concentration. The overall mass transfer in adsorption was estimated from concentration decay curves obtained in the batch adsorber. The maximum adsorption capacity decreased with increasing adsorbent amount in TiO2 adsorption. The adsorption isotherms of MM could be plotted using the Langmuir isotherm model with a reasonable degree of accuracy having higher r2 values rather than Freundlich isotherm model. Linear driving force approximation (LDFA) kinetic equation with Langmuir adsorption isotherm model was successfully applied to predict the adsorption kinetics data in various concentrations of MM in photobatch reactor. The estimated mass transfer coefficient was used to be 3.0 × 10-5, 5.5 × 10-5, 9.1 × 10-5 m/s in PAC adsorption and 2.0 × 10-5, 1.1 × 10-5, 9.0 × 10-6 m/s in TiO2 adsorption for a different MM concentration of 20, 50 and 70 mg/L, respectively. Photocatalysis kinetics was same with TiO2 of 0.2 g/L regardless of TiO2 amounts and the MM degradation kinetics was enhanced by TiO2 catalysis rather than only UV light degradation. Among the photocatalysis kinetics model with first-order, second-order and LangmuirHinshelwood (LH) model, a second-order kinetic model was found to well present the experimental data of MM by TiO2 catalyst for the range of various TiO2 amounts and MM concentration studied.
Shon, H, Phuntsho, S & Vigneswaran, S 2008, 'Effect of Photocatalysis on the Membrane Hybrid System for wastewater treatment', Desalination, vol. 225, no. 1-3, pp. 1-16.View/Download from: Publisher's site
An integrated photocatalysismembrane hybrid system was investigated for wastewater treatment with the main focus on improving the cross flow microfiltration (MF) permeate flux. Photocatalysis with TiO2 (P25 Degussa) suspension as photocatalyst was applied both as pre-treatment and as inline treatment with MF. The TiO2 slurry was found to have significant effect in permeate flux for wastewater with lower dissolved organic carbon concentration. The MF flux decline due to TiO2 slurry cake on the membrane surface was minimized by allowing the TiO2 slurry to settle and by using only the supernatant for further treatment using the hybrid system. The investigation also included the study on the effect of photocatalytic reaction time and the slurry settling times on the MF permeate flux. The irradiation of ultraviolet on the MF surface in presence of TiO2 catalyst in suspension yielded in an increase in permeate flux.
Shon, H, Vigneswaran, S & Cho, J 2008, 'Comparison of Physico-Chemical Pretreatment Methods to Seawater Reverse Osmosis: Detailed Analyses of Molecular Weight Distribution of Organic Matter in Initial Stage.', Journal Of Membrane Science, vol. 320, pp. 151-158.View/Download from: Publisher's site
In desalination, effective pretreatment is the key to reduce membrane fouling that occurs during the seawater reverse osmosis (SWRO) process. However, it is difficult to compare the flux decline after different pretreatments using a small-scale reverse osmosis filtration unit. In this study, we successfully evaluated the effect of pretreatment on SWRO in terms of molecular weight distribution (MWD) of seawater organic matter (SWOM) after 20 h of SWRO operation. Microfiltration (MF), ultrafiltration (UF), ferric chloride (FeCl3) flocculation and powdered activated carbon (PAC) adsorption, were used as pretreatment. The effluents and the retentates after each pretreatment and 20 h of SWRO operation were characterized in terms of MWD. Although the normalized flux of SWRO showed similar flux decline (J/J0 = 0.17) with/without pretreatment, SWOM concentration in the retentates after different pretreatments was different in quantity and it increased linearly with time. The slope of the SWOM increase was 0.110, 0.096, 0.077 and 0.059 after MF, FeCl3 flocculation, UF and PAC adsorption pretreatments, respectively. MW peaks for the seawater used in this study consisted of 1200 Da (biopolymers), 950 Da (fulvic acids), 650 Da (hydrolysates of humic substances), 250 Da (low MW acids) and 90 Da (low MW neutrals and amphiphilics). FeCl3 flocculation preferentially removed 1200 Da (biopolymers), while PAC adsorption mostly removed 950 Da (fulvic acids). UF and NF removed only a marginal amount of relatively large organics, while RO removed the majority of organics. The intensity of 1200, 950, 650 and 250 Da MW in the RO retentates increased with the RO operation time. The organics of MW around 1200 Da (biopolymers) had a relatively low rate of increase with time compared with those of lower MW. This suggests that the SWOM of 1200 Da MW was preferentially retained on the membrane surface.
Shon, H, Vigneswaran, S, Kandasamy, JK & Shim, WG 2008, 'Ultraflitration Of Wastewater With Pretreatment: Evaluation of Flux Decline Models', Desalination, vol. 231, no. 1-3, pp. 332-339.View/Download from: Publisher's site
Three different mathematical models relating the flux decline were investigated to quantify the effects of pretreatment in a membrane filtration system. The models used are empirical flux decline model, series resistance flux decline model and modified series resistance flux decline model. A cross flow ultrafiltration unit was used to study flux decline and organic removal from synthetic wastewater. Flocculation and adsorption pretreatments were carried out with ferric chloride (FeCl3) and activated carbon of different doses. The three models could predict flux decline after different pretreatments and could be used as a pretreatment index to ultrafiltration.
Shon, HK, Phuntsho, S & Vigneswaran, S 2008, 'Effect of photocatalysis on the membrane hybrid system for wastewater treatment', DESALINATION, vol. 225, no. 1-3, pp. 235-248.View/Download from: Publisher's site
Sabina, L, Kus, BG, Shon, H & Kandasamy, JK 2008, 'Membrane fouling propensity after adsorption as pretreatment in rainwater: a detailed organic characterisation', Water Science And Technology, vol. 58, no. 8, pp. 1535-1539.View/Download from: Publisher's site
Organic characterisation in rainwater was investigated in terms of dissolved organic carbon (DOC) and molecular weight distribution (MWD) after powdered activated carbon (PAC) adsorption. PAC adsorption was used as pretreatment to membrane filtration to
Kim, SH & Shon, H 2007, 'Adsorption Characterization for Multi-Component Organic Matters by Titanium Oxide (TiO2) in Wastewater', Separation Science And Technology, vol. 42, no. 8, pp. 1775-1792.View/Download from: Publisher's site
In this study, an experimental and analytical study on adsorption and adsorption kinetics of organic matters in titanium oxide (TiO2, Degussa P25) with synthetic wastewater was investigated. In order to understand the removal of different organic sizes i
Shon, H, Smith, PJ, Vigneswaran, S & Ngo, H 2007, 'Effect Of A Hydrodynamic Cleaning Of A Cross-flow Membrane System With A Novel Automated Approach', Desalination, vol. 202, no. 1-3, pp. 351-360.View/Download from: Publisher's site
The effect of different hydraulic cleaning methods was investigated in terms of flux decline and resistance using the cross-flow UF unit. The use of varied production intervals, varied ratios of periodic relaxation and the use of a periodic high-rate cro
Shon, H, Vigneswaran, S, Kim, IS, Cho, J, Kim, G, Kim, JK & Kim, J 2007, 'Preparation of titanium dioxide (TiO2) from sludge produced by titanium tetrachloride (TiCl4) flocculation of wastewater', Environmental Science & Technology, vol. 41, no. 4, pp. 1372-1377.View/Download from: Publisher's site
Sludge disposal is one of the most costly and environmentally problematic challenges of modern wastewater treatment worldwide. In this study, a new process was developed, which has a significant potential for lower cost of waste disposal, protection of t
Shon, H, Vigneswaran, S, Kim, JH & Ngo, H 2007, 'Application of a Photocatalysis System to Wastewater: A Detailed Organic Removal of different fractions', Studies in Surface Science and Catalysis, vol. 172, pp. 559-560.
A removal of detailed organic matter by photocatalysis was investigated in terms of molecular weight (MW) distribution and fraction (hydrophobic (HP), transphilic (TP) and hydrophilic (HL)). The photooxidation with TiO, removed the majority of MW (263 daltons, 580, 865, and 43109). Effluent organic matter (EfOM) removal in wastewater was high (80%) for HP and TP components. EfOM removal from the HL fraction was however minimum, suggesting that the HL fraction may be the fraction of low activity in photocatalytic degradation. Thus, the HL fraction has to be removed from BTSE in the application of photocatalysis for the purpose of wastewater reuse
Shon, H, Vigneswaran, S, Kim, JK & Ngo, H 2007, 'Application Of Hybrid Photocatalysis Systems Coupled With Flocculation And Adsorption To Biologically Treated Sewage Effluent For Organic Removal', Korean Journal Of Chemical Engineering, vol. 24, no. 4, pp. 618-623.View/Download from: Publisher's site
The application of a photocatalysis hybrid system coupled with flocculation and adsorption in treating biologically treated sewage effluent (BTSE) was investigated. The removal of organic matter was studied in terms of dissolved organic matter (DOC), rem
Shon, H, Vigneswaran, S, Ngo, H, Kim, JK & Kandasamy, JK 2007, 'Effect Of Flocculation As A Pretreatment To Photocatalysis In The Removal Of Organic Matter From Wastewater', Separation And Purification Technology, vol. 56, no. 3, pp. 388-391.View/Download from: Publisher's site
Effects of different flocculants (chloride-based salts and ferric and ferrous salts) and initial organic concentration of wastewater on flocculation-photocatalysis hybrid process were investigated. Titanium dioxide (TiO2) adsorption alone, flocculation a
Vigneswaran, S, Shon, H, Kandasamy, JK & Shim, WG 2007, 'Performance of Granular Activated Carbon (GAC) adsorption and biofiltration in the treatment of biologically treated sewage effluent', Separation Science and Technology, vol. 42, no. 14, pp. 3101-3116.View/Download from: Publisher's site
In this study, the performance of GAC adsorption and biofiltration systems in treating biological treated sewage effluent (BTSE) was evaluated in terms of organic removal efficiency, organic fractions, and molecular weight distribution (MW) of organic matter (OM) removed. The GAC biofilter removed 23.5% and 61% of the hydrophobic fractions and hydrophilic fractions of OM in the BTSE respectively. MW distribution studies of GAC filter and GAC adsorption revealed the following: Hydrophobic fraction of the effluent showed a peak at 345 dalton after GAC biofiltration and 256 dalton after GAC adsorption, whereas, with hydrophilic fractions, peaks at 46,178 and 345 daltons were observed after GAC biofiltration and peaks at 46,178 and 256 daltons after GAC adsorption. Transphilic fraction showed the peaks at 12,783 dalton with GAC biofiltration, and 1,463 dalton with GAC adsorption. The performance of the GAC biofilter was successfully mathematically modelled.
Shon, H, Erdei, L & Kim, J 2006, 'Constituent of Natural Organic Matter (NOM) and its effect in water', Journal of the Korean Industrial and Engineering Chemistry, vol. 17, no. 2, pp. 119-124.
Natural organic matter (NOM) should be carefully considered in terms of its constituent and effect because NOM is complex substances that occur in spatially and seasonally varying concentrations in natural water. This review presents characteristics of natural organic matter present in water. These compounds mainly include humic substances, carbohydrates, proteins (amino acids), hexosamines, fats, oils, greases, and trace organic compounds (endocrine disrupting chemicals and pharmaceuticals and personal care products)
Areerachakul, N, Shon, H, Vigneswaran, S & Ngo, H 2006, 'Photocatalytic hybrid system in degradation of herbicide (metsulfuron-methyl)', Water Science & Technology: Water Supply, vol. 6, no. 2, pp. 109-114.View/Download from: Publisher's site
Photocatalytic oxidation is becoming an emerging technology in water and wastewater Photocatalysis often leads to complete degradation of organic pollutants without any need for chemicals. this study, the removal of the herbicide metsulfuron-methyl (MM)
Jang, NJ, Shon, H, Ren, X, Vigneswaran, S & Kim, IS 2006, 'Characteristics of Bio-Foulants in the Membrane Bioreactor', Desalination, vol. 200, no. 1-3, pp. 201-202.View/Download from: Publisher's site
Shon, H, Kim, SH, Erdei, L & Vigneswaran, S 2006, 'Analytical methods of size distribution for organic matter in water and wastewater', Korean Journal Of Chemical Engineering, vol. 23, no. 4, pp. 581-591.View/Download from: Publisher's site
Organic matter (OM), such as natural organic matter (NOM) in surface waters, and effluent organic matter (EfOM) in wastewaters causes many problems. For example, color, taste and odor derogate potable water quality, while the presence of endocrine disrup
Shon, H, Vigneswaran, S & Ngo, H 2006, 'Effect of partial flocculation and adsorption as pretreatment to ultrafiltration', Aiche Journal, vol. 52, no. 1, pp. 207-216.View/Download from: Publisher's site
In this study, the sufficiency of flocculation and adsorption with reduced doses of ferric chloride and powdered activated carbon (PAC) as pretreatment to ultrafiltration. (UF) was investigated. A 50 mg/L dose of FeCl3 and 0.5 g/L of PAC removed a majori
Shon, H, Vigneswaran, S & Snyder, S 2006, 'Effluent organic matter (EfOM) in wastewater Constituents, effects, and treatment', Critical Reviews In Environmental Science And Technology, vol. 36, no. 4, pp. 327-374.View/Download from: Publisher's site
Wastewater reuse is being increasingly emphasized as a strategy for conservation of limited resources of freshwater and as a mean of safeguarding the aquatic environment due to contaminants present in wastewater. Although secondary and tertiary treated w
Shon, H, Vigneswaran, S, Kim, I, Cho, J & Ngo, H 2006, 'Fouling of ultrafiltration membrane by effluent organic matter A detailed characterization using different organic fractions in wastewater', Journal Of Membrane Science, vol. 278, no. 1-2, pp. 232-238.View/Download from: Publisher's site
Membrane fouling caused by hydrophobic (HP), transphilic (TP), and hydrophilic (HL) fractions in biologically treated sewage effluent (BTSE) are still not well understood. Some researches reported that the HP fraction (humic substances) were the major pr
Shon, H, Vigneswaran, S, Ngo, H, Johnston, AJ, Kim, IS & Cho, J 2006, 'Performance of Flocculation and Adsorption Pretreatments to Ultrafiltration of Biologically Treated Sewage Effluent: the Effect of Seasonal Variations', Separation Science and Technology, vol. 41, no. 16, pp. 3585-3596.View/Download from: Publisher's site
The effect of seasonal variations on ultrafiltration (UF) following pretreatment was investigated in terms of organic removal, removal of fraction, and molecular weight (MW) distribution. The MW range of effluent organic matter (EfOM) in biologically treated sewage effluent during winter (BTSE-W) consisted of large MW. However, the MW ranged from 3000 to 200 daltons in biologically treated sewage effluent in the summer (BTSE-S). During filtration experiments of BTSE-S, the UF NTR 7410 filter showed rapid flux decline with time without pretreatment. FeCl3 flocculation removed the hydrophobic (HP) and hydrophilic (HL) fractions with different trends. In winter the HP fraction was removed up to 68.5%, whereas during the summer season, the HL fraction was removed by up to 59.8%. Flocculation removed large MW organics together with small MW, while PAC removed the majority of small MW organics. The flux decline with adsorption was also more severe than that with flocculation. Considering MW distribution, when large MW was removed by flocculation, the flux decline was minimized, whereas PAC adsorption which removed small MW still decreased the permeate flux.
Smith, PJ, Shon, H, Vigneswaran, S, Ngo, H & Nguyen, HT 2006, 'Productivity enhancement in a cross-flow ultrafiltration membrane system through automated de-clogging operations', Journal Of Membrane Science, vol. 280, no. 1-2, pp. 82-88.View/Download from: Publisher's site
A membrane system only has a limited operational lifetime, whereby it becomes so severely fouled that continued operation must be stopped. In the cross-flow configuration of membrane filtration of wastewater, both increased cross-flow velocities and decr
Smith, PJ, Shon, HK, Vigneswaran, S, Ngo, HH & Nguyen, H 2006, 'Productivity enhancement in a cross-flow ultrafiltration membrane system through automated de-clogging operations', Journal of Membrane Science, vol. 280, no. 1-2, pp. 82-88.
A membrane system only has a limited operational lifetime, whereby it becomes so severely fouled that continued operation must be stopped. In the cross-flow configuration of membrane filtration of wastewater, both increased cross-flow velocities and decreased operational transmembrane pressures can be used to decrease membrane fouling and extend the life cycle of the membrane separation process. The study found that an optimised usage of two de-clogging techniques, with a 1 h production period followed by a 1 min relaxation period and then a 1 min high cross-flow rate period, resulted in a net productivity increase of 14.8%. The study involved a detailed investigation into the utilization of two automated cleaning techniques to reduce fouling problems encountered when cross-flow membrane systems are operated with high permeate flux rates. The two cleaning techniques studied were periodic membrane relaxation and a periodic high rate cross-flow. During both the relaxation and high rate cross-flow periods, permeate production was stopped. This results in an operational loss in productivity. When each cleaning technique was operated individually, there was a net productivity decrease of 0.7%, due to the 3.2% operational loss due to cleaning technique being implemented. The system was developed using a Programmable Logic Controller (PLC) and a Supervisory Control and Data Acquisition (SCADA) system to accurately control and monitor the process. © 2006 Elsevier B.V. All rights reserved.
Shon, H, Vigneswaran, S, Ben Aim, RM, Ngo, H, Kim, IS & Cho, J 2005, 'Influence of flocculation and adsorption as pretreatment on the fouling of ultrafiltration and nanofiltration membranes: Application with biologically treated sewage effluent', Environmental Science & Technology, vol. 39, no. 10, pp. 3864-3871.View/Download from: Publisher's site
Membrane fouling is a critical limitation on the application of membranes to wastewater reuse. This work aims to understand the fouling phenomenon which occurs in ultrafiltration (UF; 17500 molecular weight cutoff (MWCO)) and nanofiltration (NF; 250 MWCO
Shon, H, Vigneswaran, S, Kim, H, Ngo, H & Park, N 2005, 'Comparison of nanofiltration with flocculation - microfiltration - photocatalysis hybrid system in dissolved organic matter removal', Filtration: International Journal for Filtration and Separation, vol. July, pp. 215-221.
In this research, a NTR 729HF nanofiltration (NF) membrane was employed to remove synthetic organic matter (SOM) from wastewater. NF alone led to a removal of 92.4% of dissolved organic carbon (DOC). The performance of NF was compared with that of a microfiltration (MF) hybrid system consisting of FeCl3 flocculation, MF and photocatalysis. Flocculation and microfiltration followed by photocatalysis led to more than 96% dissolved organic carbon (DOC) removal. A detailed molecular weight (MW) distribution study of organic matter indicated that the photocatalysis initially breaks the large MW organics and then the small MW organics were removed by a photoreactor process. Flocculation with an optimum dose of FeCl3 (68 mg/L as FeCl3) gave rise to the highest removal of organics including small MW organics. The small MW organics remaining after the treatment of flocculation could successfully be removed by photocatalysis.
Shon, H, Vigneswaran, S, Ngo, H & Aim, RB 2005, 'Is semi-flocculation effective as pretreatment to ultrafiltration in wastewater treatment?', Water Research, vol. 39, no. 1, pp. 147-153.View/Download from: Publisher's site
In this study, ferric chloride (FeCl3) flocculation was used as a pretreatment to ultrafiltration (UF) in treating synthetic wastewater containing synthetic organic matter (SOM). The effect of flocculant dose was studied in terms of organic removal and m
Shon, H, Vigneswaran, S, Ngo, H & Kim, JK 2005, 'Chemical coupling of photocatalysis with flocculation and adsorption in the removal of organic matter', Water Research, vol. 39, no. 12, pp. 2549-2558.View/Download from: Publisher's site
An experimental investigation was made to study the effects of chemical coupling of flocculation and adsorption with photocatalysis in treating persistent organic pollutants in wastewater. The photocatalysis alone showed initial reverse reaction when tit
Shon, H, Vigneswaran, S, Ngo, H, Kim, I & Ben Aim, RM 2005, 'Foulant characterization of the NF membranes with and without pretreatment of biologically treated wastewater', Water Science And Technology, vol. 51, no. 6-7, pp. 277-284.
In this study, different pretreatment methods such as ferric chloride (FeCl3) flocculation and powdered activated carbon (PAC) adsorption were evaluated in terms of their capability in removing effluent organic matter (EfOM) and the characteristics of th
Shon, H, Vigneswaran, S, Ngo, H, Kim, IS & Ben Aim, RM 2005, 'Foulant Characterization of the NF Membranes with and without Pretreatment of Biologically Treated Wastewater', Water Science And Technology, vol. 51, no. 6-7, pp. 277-284.
In this study, different pretreatment methods such as ferric chloride (FeCl3) flocculation and powdered activated carbon (PAC) adsorption were evaluated in terms of their capability in removing effluent organic matter (EfOM) and the characteristics of the foulants on the NF membranes. A detailed experiment was conducted with two NF membranes (NTR 729HF with MWCO 700 daltons and LF 10 with MWCO 200 daltons). With pretreatment, the concentration of organic matter on the membranes decreased to 5.67110+3 (NTR 729HF) and 4.94010+3 (LF 10) mg EfOM/cm2 of membrane from 6.37210+3 (NTR 729HF) and 4.97910+3 (LF 10) mg EfOM/cm2 of membrane. The MW of the solute fraction of biologically treated sewage effluent (BTSE) ranged from 250 daltons to about 3573 (the most important being 250-520 daltons). The weight-averaged MW values of the foulants on the NTR 729HF membrane reduced from 304 daltons without pre-treatment to 208 daltons with pretreatment. In the case of EfOM, the small molecules (MW 300 to 500 daltons) are mainly responsible for the membrane fouling. Thus, the MW distribution of organic matter in the effluent and in the foulant can be used as a representative tool to evaluate the efficiency of pretreatment and NF and in the selection of their operating conditions.
Shon, HK, Vigneswaran, S, Ngo, HH & Aim, RB 2005, 'Is semi-flocculation effective as pretreatment to ultrafiltration in wastewater treatment?', WATER RESEARCH, vol. 39, no. 1, pp. 147-153.View/Download from: Publisher's site
Hoang, T, Shon, H, Chaudhary, DS, Vigneswaran, S & Ngo, H 2004, 'Granular Activated Carbon (GAC) Biofilter For Low Strength Wastewater Treatment', Fluid/Particle Separation Journal, vol. 16, no. 2, pp. 185-191.
Shon, H, Guo, W, Vigneswaran, S, Ngo, H & Kim, IS 2004, 'Effect of flocculation in membrane-flocculation hybrid system in water reuse', Separation Science And Technology, vol. 39, no. 8, pp. 1871-1883.View/Download from: Publisher's site
Preflocculation reduces the fouling of membranes in cross-flow microfiltration (CFM) thus leading to high quality product water at economic filtration flux. As such, this hybrid system will have a major impact in treatingthe biologically treated sewage effluent. The preflocculation achieved through the floating medium flocculation (FMF) was found to increase the phosphorus removal up to 96%. The decline in microfiltration permeate flux with time was reduced by the incorporation of flocculation. However, the improvement in the removal of dissolved organic carbon (DOC) was marginal (from 20% with membrane alone to 46% with the membrane-flocculation hybrid system). The flocculation followed by adsorption as pretreatment helped to increase the DOC removal as high as 98%. Flocculation was found to remove more than 66% of colloidal effluent organic matter (EfOM). An attempt was also made to quantify the hydrophobic fraction in the pretreated effluent and to identify the molecular weight (MW) range of organics removed by the flocculation. The pretreatment of flocculation was found to remove 68.5%, 61.8%, and 62.9% of hydrophobic, hydrophilic, and transphilic organic matter. The MW size distribution analysis indicated that flocculation with ferric chloride removed a majority of organic matter in the MW range of 300-5000 Da.
Shon, H, Vigneswaran, S, Kim, IS, Cho, J & Ngo, H 2004, 'The effect of pretreatment on the fouling of membranes: application in biologically treated sewage effluent', Journal Of Membrane Science, vol. 234, no. 1-2, pp. 111-120.View/Download from: Publisher's site
Reuse of wastewater can help in maintaining environmental quality and relieving the unrelenting pressure on conventional and natural freshwater sources. Membrane processes find an important place in the wastewater treatment for reuse. Nonetheless, reverse osmosis (RO) and nanofiltration (NF), i.e. non-porous membranes require higher operational costs and energy. Thus, in this research NTR 7410 ultrafiltration (UF) membrane which is porous was used without and with pretreatment to treat biologically treated sewage effluent (BTSE). Four different pretreatment methods, namely, ferric chloride (FeCl3) flocculation, powdered activated carbon (PAC) adsorption, flocculation followed by adsorption, and granular activated carbon (GAC) biofilter were used in this study to compare their relative merits. Experimental results indicate that the most suitable pretreatment was flocculation followed by adsorption leading to a total organic carbon (TOC) removal of 90%. To assess the suitability of the membranes, it is important to conduct a detailed membrane characterization. The fouled NTR 7410 membrane surface was analyzed in terms of contact angle, zeta potential, attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), flux decline, and TOC removal. The contact angle of the fouled membrane surface was lower than that of the clean membrane surface. This suggests that the majority of the foulants may have been the hydrophilic organic compounds such as polysaccharides, urea, etc. which are the extracellular enzyme of microorganisms in BTSE
Shon, H, Vigneswaran, S, Kim, IS, Cho, J & Ngo, H 2004, 'The effect of pretreatment to ultrafiltration of biologically treated sewage effluent: a detailed effluent organic matter (EfOM) characterization', Water Research, vol. 38, pp. 1933-1939.View/Download from: Publisher's site
Vigneswaran, S, Shon, H, Boothanon, H, Ngo, H & Ben-Aim, R 2004, 'Membrane-flocculation-adsorption Hybrid System in Wastewater Treatment: Micro and Nano Size Organic Matter Removal', Water Science and Technology, vol. 50, no. 12, pp. 265-271.
Tian, D, Shon, HK, Chun, DJ, Jin, CS, Gwon, EM & Chung, WJ 2003, 'Isolation and characterization of sulfur-utilizing denitrifiers from the sulfur-oxidizing denitrification process', BIOTECHNOLOGY LETTERS, vol. 25, no. 19, pp. 1605-1608.View/Download from: Publisher's site
Shon, HK, Tian, D, Kwon, DY, Jin, CS, Lee, TJ & Chung, WJ 2002, 'Degradation of fat, oil, and grease (FOGs) by lipase-producing bacterium Pseudomonas sp strain D2D3', JOURNAL OF MICROBIOLOGY AND BIOTECHNOLOGY, vol. 12, no. 4, pp. 583-591.
Damtie, MM, Volpin, F, Yao, M, Tijing, LD, Hailemariam, RH, Bao, T, Park, K-D, Shon, HK & Choi, J-S, 'Ammonia Recovery from Human Urine as Liquid Fertilizers in Hollow Fiber Membrane Contactor: Effects of Permeate Chemistry', Environmental Engineering Research.View/Download from: Publisher's site
Aryal, RK, Vigneswaran, S, Lebegue, J, Shon, HK, Kandasamy, J, Heran, M & Grasmick, A, 'Organic Foulants Characteristics in Membrane Bioreactor', Journal of Applied Membrane Science & Technology, vol. 5, no. 1.View/Download from: Publisher's site
A laboratory scale side stream membrane bioreactor system with flat sheet membrane was operated for 5–days run at three different aeration rates (100, 200 and 300 L/h). The organic foulants deposited on the membrane surface was studied after extraction with 5% NaOH solution using three spectroscopic techniques. The IR spectra showed no distinct similarity in peaks among the three. The fluorescence spectra showed increase of soluble microbial products in foulant with decrease of aeration rate. This was supported by the size exclusion chromatography in which biopolymers concentration in fouling decreased with increasing aeration rate.
Pathak, N, Tran, VH, Merenda, A, Johir, MAH, Phuntsho, S & Shon, H, 'Removal of Organic Micro-Pollutants by Conventional Membrane Bioreactors and High-Retention Membrane Bioreactors', Applied Sciences, vol. 10, no. 8, pp. 2969-2969.View/Download from: Publisher's site
The ubiquitous presence of organic micropollutants (OMPs) in the environment as a result of continuous discharge from wastewater treatment plants (WWTPs) into water matrices—even at trace concentrations (ng/L)—is of great concern, both in the public and environmental health domains. This fact essentially warrants developing and implementing energy-efficient, economical, sustainable and easy to handle technologies to meet stringent legislative requirements. Membrane-based processes—both stand-alone or integration of membrane processes—are an attractive option for the removal of OMPs because of their high reliability compared with conventional process, least chemical consumption and smaller footprint. This review summarizes recent research (mainly 2015–present) on the application of conventional aerobic and anaerobic membrane bioreactors used for the removal of organic micropollutants (OMP) from wastewater. Integration and hybridization of membrane processes with other physicochemical processes are becoming promising options for OMP removal. Recent studies on high retention membrane bioreactors (HRMBRs) such as osmotic membrane bioreactor (OMBRs) and membrane distillation bioreactors (MDBRs) are discussed. Future prospects of membrane bioreactors (MBRs) and HRMBRs for improving OMP removal from wastewater are also proposed.
Shon, HK, Phuntsho, S, Chaudhary, DS, Vigneswaran, S & Cho, J, 'Nanofiltration for water and wastewater treatment – a mini review', Drinking Water Engineering and Science Discussions, vol. 6, no. 1, pp. 59-77.View/Download from: Publisher's site
Abstract. The application of membrane technology in water and wastewater treatment is increasing due to stringent water quality standards. Nanofiltration (NF) is one of the widely used membrane processes for water and wastewater treatment in addition to other applications such as desalination. NF has replaced reverse osmosis (RO) membranes in many applications due to lower energy consumption and higher flux rates. This paper briefly reviews the application of NF for water and wastewater treatment including fundamentals of membrane process in general, mechanisms of NF process including few basic models. fouling challenges and their control mechanisms adopted.
Pathak, N, Tran, VH, Phuntsho, S & Shon, HY 2020, 'Membrane bioreactors for the removal of micro-pollutants' in Current Developments in Biotechnology and Bioengineering, Elsevier, pp. 231-252.View/Download from: Publisher's site
Tran, VH, Pathak, N & Shon, HY 2020, 'Osmotic membrane bioreactor technology—Concept, potential and challenges' in Current Developments in Biotechnology and Bioengineering, Elsevier, pp. 181-207.View/Download from: Publisher's site
Tijing, L, Yao, M, Ren, J, Park, C-H, Kim, CS & Shon, H 2019, 'Nanofibers for Water and Wastewater Treatment: Recent Advances and Developments' in Bui, X-T, Chiemchaisri, C, Fujioka, T & Varjani, S (eds), Water and Wastewater Technologies, Springer, Singapore, pp. 431-468.
© 2019 Elsevier Inc. All rights reserved. In recent decades, many regions of the world have suffered from water scarcity, which is one of the most critical issues in the world. The main challenge is to supply freshwater to water shortage regions. In addition, waterborne illness has been caused through the consumption of the contaminated potable water in these regions. Increasing demands of potable water and the deficiency of surface water resources led to the development of desalination technologies, which obtain freshwater from seawater. This chapter addresses general information on desalination technologies in terms of the historical development, current status, and future prospects. It begins with the description of backgrounds in terms of the development of desalination technologies. Section 2 is an overview of the historical development of desalination technologies, including multistage flash, multieffect distillation, and reverse osmosis. Section 3 focuses on the reduction of energy consumption of the desalination technologies and increase of the permeate volume by energy recovery device, improved membrane, and hybrid conventional process. In Section 4, several alternative desalination technologies, membrane fabrication techniques, and brine management methods are introduced. Future trends of desalination technologies are pointed out in the final section.
Woo, YC, Yao, M, Tijing, LD, Lee, S-E & Shon, HK 2018, 'Recent Progress in the Fabrication of Electrospun Nanofiber Membranes for Membrane Distillation' in Advanced Materials for Membrane Fabrication and Modification, CRC Press, pp. 71-100.View/Download from: Publisher's site
Lim, S & Shon, H 2018, 'Characterization of Membranes for Membrane-Based Salinity-Gradient Processes' in Membrane-Based Salinity Gradient Processes for Water Treatment and Power Generation, Elsevier, The Netherlands, pp. 125-154.View/Download from: Publisher's site
Pressure retarded osmosis (PRO) is one of the alternative applications for harvesting renewable energy by a natural phenomenon. As a particular free energy, the salinity gradient energy (SGE) from saline solutions with different concentrations has recently been revitalized as a renewable energy source. In recent studies for development of PRO membranes, various attempts and novel applications have been conducted for enhancing energy production as well as an ease of the membrane modulation. At this stage, newly developed PRO membranes should be clearly characterized and evaluated to find the reason why novel approaches are attractive for its performance improvement compared to commercial and existing PRO membranes. In this chapter, therefore we would like to suggest the guideline for PRO membrane characterization in which most of contents are made of various attempts and investigations in literature. This chapter aims to understand various characterizations for PRO membranes to confirm the proof of the performance improvement for its purpose.
Tijing, LD, Shon, HK, Woo, YC, Yao, M & Ren, J 2017, 'Electrospinning for Membrane Fabrication: Strategies and Applications' in Drioli, E, Giorno, E & Fontananova, E (eds), Comprehensive Membrane Science and Engineering, Elsevier, England, pp. 418-444.
Kim, SH, Lee, SH, Tijing & Shon, H 2016, 'Filtration technologies for pretreatment of seawater desalination based on reverse osmosis' in Efficient desalination by reverse osmosis : a best practice guide to RO, IWA Publishing (International Water Assoc), London, pp. 28-60.
Efficient Desalination by Reverse Osmosis provides a complete guide to best practice from pre-treatment through to project delivery. It is written for utility managers & professionals.
El Saliby, I, McDonagh, A, Erdei, L & Shon, HK 2016, 'Water reclamation by heterogeneous photocatalysis over titanium dioxide' in Green Technologies for Sustainable Water Management, pp. 679-704.View/Download from: Publisher's site
© 2016 American Society of Civil Engineers. This chapter presents the fundamentals and basic principles of water reclamation by heterogeneous photocatalysis (HP). The effects of important operational parameters on the overall treatment efficiency of photocatalytic system are addressed in the chapter in terms of photocatalyst loading, pollutant concentration, pH and temperature of water, dissolved oxygen, and light intensity. The most popular semiconductor used in HP is Titanium dioxide (TiO2) for being relatively inexpensive, chemically stable, and nontoxic. Most water remediation technologies generate a significant amount of wastewater that requires costly retreatment or discharge to evaporation ponds, rivers, and oceans. HP processes that decompose aqueous contaminants are highly dependent on the reaction conditions and the setup of photocatalytic reactors. Visible-light responsive photocatalysts promise a more effective utilization of solar energy. Doping and co-doping of titania is a practical approach toward obtaining improved visible-light active photocatalysts.
Phuntsho, S, Kim, J, Majeed, T, Lotfi, F, Sahebi, S, Park, S & Shon, HK 2015, 'Fertiliser-Drawn Forward Osmosis Desalination for Fertigation' in Shon, HK, Phuntsho, S, Zhang, TC & Surampalli, RY (eds), Forward Osmosis: Fundamentals and Applications, American Society of Civil Engineers, Reston, Virginia, USA, pp. 395-426.View/Download from: Publisher's site
This chapter explains the concept of the fertilizer-drawn forward osmosis (FDFO) desalination process and evaluates the potential of fertilizer solutions as draw solutions (DS). Different types of fertilizers are used to grow crops, and hence understanding what types of fertilizers are more suitable for the FDFO desalination process and how to screen and assess suitable fertilizer candidates for use as DS in the FDFO desalination process is important. FDFO desalination adds value to irrigation water and provides more opportunities for improving the efficiencies of water and fertilizer use. The major limitations of the FDFO desalination process are the challenge of meeting the irrigation water quality standards in terms of nutrient concentrations, which limits the direct use of FDFO product water for fertigation. Several options are discussed that could be integrated with the FDFO desalination process to reduce the final nutrient concentration closer to an acceptable limit.
Chekli, LM, Shon, HK, Phuntsho, S, Kim, J & Cho, J 2015, 'Draw Solutes in Forward Osmosis Processes' in Shon, HK, Phuntsho & Zhang, T (eds), Forward Osmosis: Fundamentals and Applications, American Society of Civil Engineers, USA, pp. 85-113.View/Download from: Publisher's site
This chapter provides insight into the selection of suitable draw solutions (DS) and reviews different DS characteristics affecting the performance of forward osmosis (FO) processes. Although some commercial applications of FO technology exist, the development of an effective large-scale process is currently limited due to the lack of both suitable DS and membrane. The success of most FO applications also relies on how the DS can be recovered from the produced water. Therefore, in commercial FO processes, such as FO followed by reverse osmosis seawater desalination, emergency drinks and osmotic dilution are used without a DS recovery system—a simple and energy-saving solution. Research is still needed to develop more suitable DS to achieve full-scale commercialization of the FO process.
Hong, S & Shon, HK 2015, 'Membrane fouling in forward osmosis processes' in Forward Osmosis: Fundamentals and Applications, American Society of Civil Engineers, pp. 217-240.View/Download from: Publisher's site
© 2015 by the American Society of Civil Engineers. All Rights Reserved. Several filtration systems have been applied to advanced water treatment and even conventional water treatment processes. Although the membrane filtration systems are the most feasible alternative for water treatment, several problems still remain for efficient operation of membrane filtration. Among these problems, fouling is one of the major challenges to overcome in membrane technology. Reverse osmosis (RO) membrane is a polyamide thin-film composite membrane and forward osmosis (FO) membrane is a cellulose-based membrane, thus fouling could differ between RO and FO due to different membrane surface characteristics, which are discussed in this chapter. The chapter also discusses various strategies that mitigate fouling formation in the FO process in terms of spacers, cross-flow velocity, air scouring, cross-flow type, and osmotic backwashing. The osmotic backwashing is applied to an osmotic membrane bioreactor system that utilizes a submerged FO membrane in the bioreactor.
Li, XM, Chen, G, Shon, HK & He, T 2015, 'Treatment of high salinity waste water from shale gas exploitation by forward osmosis processes' in Forward Osmosis: Fundamentals and Applications, American Society of Civil Engineers, pp. 339-362.View/Download from: Publisher's site
© 2015 by the American Society of Civil Engineers. All Rights Reserved. This chapter reviews state-of-the-art treatment of shale-gas-produced water with a focus on the treatment of shale-gas flow-back water (SGW) by forward osmosis (FO). It briefly introduces the origin and chemical/physical characteristics of SGW. Management of shale-gas wastewater depends on multidimensional criteria, e.g., local regulations, site conditions, water quality, and economic feasibility. Approaches used to treat high-salinity wastewater include deep well injection, transport and centralized treatment, treatment and disposal, and reuse. The chapter analyzes the advantages and limitations of potential treatments methods and summarizes the process parameters and selection of membrane and draw solutions. Studies were performed to examine the effectiveness of FO in treating high-salinity wastewater produced from shale-gas exploitation. The chapter discusses the potential for using the FO process to treat SGW on a large scale.
Phuntsho, S, Shon, HK, Zhang, TC & Surampalli, R 2015, 'Introduction: Role of membrane science and technology and forward osmosis processes' in Forward Osmosis: Fundamentals and Applications, American Society of Civil Engineers, pp. 1-14.View/Download from: Publisher's site
© 2015 by the American Society of Civil Engineers. All Rights Reserved. This introduction presents an overview of the book’s key concepts. The book’s main objective is to introduce the principles and concept of the forward osmosis (FO) process and the potential for various applications, such as desalination, fertigation, wastewater reuse, and mine water treatment. The book also covers other important aspects of the FO process such as membrane fabrication and modeling. The introduction briefly outlines each chapter, including various water treatment technologies available on the market. One of the most advanced and reliable water treatment technologies is the membrane process. Depending on the membrane pore size and its removal capacity, the membrane process is classified into four different types: microfiltration, ultrafiltration, nanofiltration. and reverse osmosis.
El Saliby, I, Shon, H & McDonagh, AM 2013, 'Visible-light active doped titania for water purification: nitrogen and silver doping' in Lens, PNL, Virkutyte, J, Jegatheesan, V, Kim, SH & Al-Abed, S (eds), Nanotechnology for Water and Wastewater Treatment, IWA Publishing, London, UK, pp. 189-208.
Photocatalysis over semiconductors, mainly Ti02, has been employed and extensively studied over the past few decades (Malato et aI., 2009). The so-called "first generation photocatalYSIS" are characterised by their photoexcitation limited to the UV region of the solar spectrum. Nevertheless, many photocatalysts showed outstanding performance in decomposing a large number of pollutants of water and air. A number of water pollutants belong to the family of biorecalcitrant pollutants (non-biodegradable) and these include pharmaceutical and personal care products, industrial wastes, and a large number of pesticides/herbicides. Many of the emerging pollutants are resistant to conventional water treatment processes, noxious to the environment and some are classified as endoctine disrupting agents. The removal of non-biodegradable pollutants from wastewater poses a serious challenge for the water industry. Generally, advanced oxidation processes (AOP) are employed to achieve this goal. Heterogeneous photocatalysis, as part of AOP, is sometimes adopted as a tool to eliminate these contaminants. However, the high cost associated with the use of photocatalysis to treat such compounds has always been a disadvantage for its large-scale adoption in treatment processes. The high cost is mainly associated with: (1) the energy consumed for the UV light irradiation of the photocatalyst, (2) the energy required for the separation of the photocatalyst particles from water. A total of 40% of the solar light reaching the lithosphere is visible light, whereas UV light accounts only for 5% of the total solar radiation. The development of new photocatalysts that can effectively harvest visible light is crucial for making this technology viable in the waler treatment industry. The use of "second-generation riOz photocatalysts" to harvest visible light from solar energy is gaining popularity (Anpo, 1997). Most of the research involving the use of second generation TiOz photocatalysts has...
Cho, J, Ramínez, JAL, Shon, HK, Park, K & Park, M 2012, 'Sustainable Water Treatment sustainability/sustainable water treatment Using Nanofiltration and Tight Ultrafiltration Membranes' in Encyclopedia of Sustainability Science and Technology, Springer New York, pp. 10530-10542.View/Download from: Publisher's site
Everett, JW 2012, 'Waste Waste Collection solid waste collection and Transport solid waste transport(ing) Solid wastes Transport' in Encyclopedia of Sustainability Science and Technology, Springer New York, pp. 11655-11673.View/Download from: Publisher's site
Kim, IS, Oh, BS, Yoon, S, Shon, H, Lee, S & Hong, S 2012, 'Wastewater Wastewater Reclamation wastewater reclamation' in Encyclopedia of Sustainability Science and Technology, Springer New York, pp. 11873-11891.View/Download from: Publisher's site
Meujo, DAF & Hamann, MT 2012, 'Science, Policy, and Risk Management: Case of Seafood Safety seafood regulatory authorities safety' in Encyclopedia of Sustainability Science and Technology, Springer New York, pp. 9079-9109.View/Download from: Publisher's site
Shon, H 2012, 'Removal of lower-molecular-weight substances from water and wastewater : challenges and solutions' in Wastewater Treatment Advanced Processes and Technologies, CRC Press.
These features combine to make the book an authoritative resource and practical tool for resolving wastewater treatment issues.
Shon, H, Phuntsho, S, Vigneswaran, S, Kandasamy, JK, Aryal, R & Jegatheesan, V 2012, 'Physical, Chemical, and Biological Characterization of Membrane Fouling' in Zhang, TC, Surampalli, RY, Vigneswaran, S, Tyagi, RD, Ong, SL & Kao, CM (eds), Membrane Technology and Environmental Applications, American Society of Civil Engineers, USA, pp. 457-497.
In this chapter, advanced characterization of membrane fouling as a diagnostic tool has been summarized to prevent membrane fouling. Physical, chemical and biological analyses as membrane autopsies are mainly utilized to better understand membrane foulant. The physical characteri zation gives structure, roughness, charge effect, strength and hydrophobicity of membrane fouling. The chemical methods provide qualitative and quantitative measurements of different inorganic and organic matter. The biological properties present the spatial biofilm distribution, structure of dominant microorgnisms and isolation and identification of microorganisms. In addition, detailed membrane foulant types are reviewed in terms of structure, roughness, hydrophobicity, charge effect, strength, calcium, magnesium, alluminum, iron, silicate, particle, functional group, biopolymer, humic acid, polysaccharide, structural composition, biofilm structure, microorganism and foulant interaction.
Vigneswaran, S, Sathananthan, S, Shon, HK, Kandasamy, J & Visvanathan, C 2012, 'Delineation of membrane processes' in Membrane Technology and Environmental Applications, American Society of Civil Engineers, pp. 41-74.View/Download from: Publisher's site
Johir, MA, Orem, Y, Messalem, R, Ben-David, E, Herzberg, M, Kushmaro, A, Ji, X, Di Profio, G, Curcio, E, Drioli, E, Laroche, JF, Remize, P, Leparc, J, Vigneswaran, S, Chinu, KJ, Lee, J, Shon, H, Kandasamy, JK, Ye, Y, Sim, LN, Herulah, B, Chen, V, Fane, AC, Tansakul, C, Laborie, S & Cabassud, C 2011, 'Evaluation and comparison of seawater and brackish water pre-treatment' in Drioli, E, Criscuoli, A & Macedonio, F (eds), Membrane-Based Desalination: An Integrated Approach (MEDINA), IWA Publishing, UK, pp. 33-70.
Membrane technology has been increasingly applied in water and wastewater treatment. Membrane
filtration involves separation of dissolved, colloidal, and particulate constituents from a pressurized
fluid using microporous materials. Membranes are categorized into four main groups based on
the size of their pores, namely, reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), and
Microfiltration with the largest pore size of 0.1–10 μm is commonly used to separate suspended
particulates, large colloids, and bacteria; hence, it is suitable for the treatment of water that has high
turbidity and low color or organics content (Schafer, 2001). Similarly, ultrafiltration (0.001–0.1 μm)
can exclude macromolecules and fine colloidal suspensions such as proteins, dyes, and bacteria, but
the removal of dissolved organics is limited. MF and UF can also be used as pretreatment for NF
and RO processes (Schafer, 2001).
Nanofiltration with smaller pore sizes of between 15 and 30 Å is employed for water softening
and the removal of disinfection by-products (DBPs). NF can reduce 60%–80% of the hardness and
more than 90% of color-causing substances (Cheryan, 1998).
Shon, H 2009, 'Characteristics of Effluent Organic Matter in Wastewater' in Water and Wastewater Treatment Technologies, UNESCO & Encyclopedia of Life Support Systems (EOLSS), Paris, France.
Shon, H 2009, 'Membrane Technology for Organic Removal in Wastewater' in Water and Wastewater Treatment Technologies, UNESCO & Encyclopedia of Life Support Systems (EOLSS), Paris, France.
Phuntsho, S, Shon, HK, Vigneswaran, S & Kandasamy, J 2008, 'Wastewater Stablisation Ponds (WSP) For Wastewater Treatment' in Vigneswaran, S (ed), Water and Wastewater Treatment Technologies, UNESCO & Encyclopedia of Life Support Systems (EOLSS).
Many industrialised countries have achieve d high levels of wastewater treatment technologies most of which are too mechanized and automated and beyond the affordability of the poor and developing nations. Technologies that are appropriate to the developing nations are required since two third of world’s population live in developing countries.
This review focuses mainly on those technologies appropriate to the developing countries. Appropriate technology should be affordable (capital cost), have low O&M cost (sustainability), effective in meeting the discharge standards, at least nuisance (public acceptability) and is environment-friendly.
Many low cost technologies are being developed but the choice of the most appropriate technology depends on a proper evaluation of all the factors such as economic, political, social, availability, etc. Wastewater Stabilization Ponds (WSP) have been extensively used worldwide because of the simplicity in design and construction, the low capital and operating cost, are very reliable and are a sustainable technology.
Constructed wetlands not only treat wastewater but have other functions such as habitats for animals and birds, recreational areas for the visitors, etc. Other low cost technologies appropriate to developing countries such as land treatments, filtration techniques, attach growth, aeration, baffled reactor and chemically enhance primary treatment are also discussed.
Shon, HK, Phuntsho, S, Vigneswaran, S & Kandasamy, J 2008, 'Physico-Chemical Processes for Organic Removal from Wastewater Effluent' in Vigneswaran, S (ed), Water and Wastewater Treatment Technologies, UNESCO & Encyclopedia of Life Support Systems (EOLSS).
This chapter covers physio-chemical processes including advanced oxidation processes for wastewater treatment. The approach used in this chapter is to first provide a brief introduction to each of the processes followed by a brief description of the process fundamentals in removing organic matter. The removal of effluent organic matter (EfOM) in terms of dissolved organic car bon (DOC), molecular weight distribution (MWD) for each process is then explained followed by removal of endocrine disrupting chemicals (EDCs) and pharmaceutical and personal care products (PPCPs) by each process.
Shon, H, Vigneswaran, S, Kim, IS, Cho, J & Ngo, H 2004, 'Characterization of Different Treatments With Biologically Treated Sewage Effluent and Synthetic Wastewater', Enviro 04 Convention & Exhibition, Enviro 04, Enviroaust Convention Limited, Darling Harbour, Australia, pp. 1-10.
Shon, H, Vigneswaran, S, Kim, J, Ngo, H & Park, N 2004, 'Comparison of Nanofiltration with Flocculation-Microfiltration-Photocatalysis Hybrid System in Dissolved Organic Matter Removal', 9th World Filtration Congress, World Filtration Congress, The American Filtration and Separation Society, New Orleans, Louisiana, USA, pp. 1-19.
Guo, W, Vigneswaran, S, Ngo, H, Shon, H & Shimohoki, S 2003, 'Improving the Performance of a Crossflow Microfiltration in Tertiary Wastewater Treatment and Reuse By Specific Pre-Treatment Processes', ASIAN WaterQual 2003, IWA Asia-Pacific Regional Conference, IWA-Regional Publication, Bangkok, Thailand, pp. 1-8.
Kim, D, Shon, H, Vigneswaran, S & Cho, J 2003, 'Evaluating Interactions Between NOM Molecules and Various Membranes with Flow Field -Flow Fractionation', IMSTEC 2003, Fifth International Membrane Science and Technology Conference, AWA-UNESCO Membrane Centre, Sydney, Australia, pp. 1-6.
Shon, H, Vigneswaran, S, Ngo, H & Ben Aim, RM 2003, 'Low Pressure Nanofiltration with Adsorption As Pretreatment In Tertiary Wastewater Treatment for Reuse', IMSTEC 2003, International Membrane Science and Technology Conference, AWA-UNESCO Membrane Centre, Sydney, Australia, pp. 1-7.
Shon, H, Vigneswaran, S, Ngo, H & Kim, IS 2003, 'Effect of high rate Pre-Treatment on Nanofiltration Systems in Wastewater Reuse', ASIAN WaterQual 2003, IWA Asia-Pacific Regional Conference, IWA-Regional Publication, Bangkok, Thailand, pp. 1-9.