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Dr Hokyong Shon

Biography

Dr Ho Kyong Shon specialises in understanding physico-chemical water treatment processes in water, wastewater and seawater.

His research career focuses on studying advanced water characterisation and its purification. He has also concentrated on the application of membrane based desalination in detailing membrane fouling mechanisms and developing novel desalination technology.

He has published over 120 refereed journal publications including five patents and numerous international awards over the last 12 years.

He is currently supervising six PhD students and two Masters students related to membrane and nanotechnology for water purification. Two students completed their PhD in 2012 and Msc in 2011.

More information can be found at his personal website.

Professional

  • International Water Association
  • Australia Water Association
  • ASCE
Image of Hokyong Shon
Senior Lecturer, School of Civil and Environmental Engineering
Core Member, Centre for Technology in Water and Wastewater
Bachelor of Engineering - Chemical Engineering, Master of Science - Environmental Biological Engineering, MSc, Doctor of Philosophy in Engineering
 
Phone
+61 2 9514 2629
Room
CB11.11.214

Research Interests

Dr Shons main research interests are membrane technologies (forward osmosis, reverse osmosis, pretreatment, life cycle assessment); organic matter characterization; innovative wastewater treatment (new coagulant) and reuse technologies; desalination; advanced oxidation processes (TiO2 photocatalysis); and nanoparticles (nano-zero valent iron and photocatalysts) for water purification.

Can supervise: Yes

Research Student Completions (in past last 5 years): 1. Ganesh Sharma, MSc, 2011, Solar-driven electrocoagulation for water treatment 2. Yousef H. Okour, PhD, 2012, Preparation and characterisation of TiO2 from Ti-salt flocculation Current Research Students: 1. Ibrahim El Saliby, PhD, Photoreactive titanate nanomaterials for water purification systems 2. Sherub Phuntsho, PhD, A novel low-energy fertiliser-driven forward osmosis desalination 3. Mohammad Shahid, PhD, Titanium dioxide based photodesorption processes and photoreactive nanosorbent materials for water purification 4. Tahir Majeed, PhD, Membrane fouling on forward osmosis desalination processes 5. Soley Sahebi, PhD, Fabrication of thin film nanocomposite membrane for desalination 6. Laura Chekli, PhD, Environmental risk assessment of nanomaterials for soil and groundwater remediation 7. Fezeh Lotfi, MSc, A novel forward osmosis electrosorption hybrid system for energy-efficient operation 8. Jungeun Kim, MSc, A pilot-scale membrane process optimisation and modelling for desalination and wastewater reuse

  • Flud Mechanics
  • Water and Environmental Design
  • Water and Wastewater Engineering
  • Pollution Control and Waste Management

Book Chapters

El Saliby, I., Shon, H. & McDonagh, A.M. 2013, 'Visible-light active doped titania for water purification: nitrogen and silver doping' in P. N. L. Lens, J. Virkutyte, V. Jegatheesan, Seung-Hyun Kim and S. Al-Abed (eds), Nanotechnology for Water and Wastewater Treatment, IWA Publishing, London, UK, pp. 189-208.
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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 focused on energy conversion and solar cell applications (Yuan et aI., 2006). However, interest is increasing in their potential for treating water pollutants (ChatteIjee & Dasgupta, 2005; Malato et al., 2009; Rehman et al., 2009). In particular, the large surface areas of nanoparticulate Ti02 materials make them particularly interesting in this regard. In addition, the ability to introduce dopants into the Ti02 stmcture allows the optical properties of the nanomaterials to be manipulated. In this chapter, doped second generation Ti02 photocatalysts are reviewed in the context of water pollutant treatment.
Shon, H., Phuntsho, S., Vigneswaran, S., Kandasamy, J.K., Aryal, R. & Jegatheesan, V. 2012, 'Physical, Chemical, and Biological Characterization of Membrane Fouling' in Tian C. Zhang, Rao Y. Surampalli, Saravanamuthu Vigneswaran, R. D. Tyagi, See Leong Ong, C.M.Kao (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.
Orem, Y., Messalem, R., Ben-David, E., Herzberg, M., Kushmaro, A., Ji, X., Di Profio, G., Curcio, E., Drioli, E., Laroche, J.F., Remize, P., Leparc, J., Vigneswaran, S., Chinu, K.J., Johir, M.H., Lee, J., Shon, H., Kandasamy, J.K., Ye, Y., Sim, L.N., Herulah, B., Chen, V., Fane, A.C., Tansakul, C., Laborie, S. & Cabassud, C. 2011, 'Evaluation and comparison of seawater and brackish water pre-treatment' in Enrico Drioli, Alessandra Criscuofi and Francesca Macedonio (eds), Membrane-Based Desalination: An Integrated Approach (MEDINA), IWA Publishing, UK, pp. 33-70.
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The main objective of WP2 was to conduct a comprehensive evaluation on available pretreatment approaches for seawater, brackish water, and estuarinelbay water for membrane protection and recovery maximization. During the project promising results were obtained by UNlCAL and BGU on MBR as a means for reducing organic content from seawater as a step towards reducing fouling potentiaL It seems that the pretreatment in a MER system is effective at improving the water's quality (removal of TOC and EPS) for further process, but further economical and implemental examinations are necessary in order to adopt this treatment as an alternative pretreatment. The removal of particulate malter and organics from seawater by the use of biofiltration was investigated by UTS. Granular activated carbon (GAC) and anthracite were tested as a filter medium at two different velocities. The filtrate quality was evaluated by measuring the silt density index (SDI), modified fouling index (MFI) and turbidity removal. Both biofilters demonstrated similar behavior in terms of SDI and MFL In addition, fiber filter as pre-treatment of SWRO in terms ofMFI, SDI 10, pressure drop, turbidity and molecular weight distribution (MWD) was investigated with and without precoagulation. Submerged microfiltTation couplcd with physcio-chemical processes such as adsorption on powder activated carbon was investigated as well.

Conference Papers

Kim, D., Shon, H., Vigneswaran, S. & Cho, J. 2003, 'Evaluating Interactions Between NOM Molecules and Various Membranes with Flow Field -Flow Fractionation', Fifth International Membrane Science and Technology Conference, Sydney, Australia, November 2003 in IMSTEC 2003, ed Wiley, D; Chen, V, AWA-UNESCO Membrane Centre, Sydney, Australia, pp. 1-6.
Shon, H., Vigneswaran, S., Ngo, H.H. & Ben Aim, R.M. 2003, 'Low Pressure Nanofiltration with Adsorption As Pretreatment In Tertiary Wastewater Treatment for Reuse', International Membrane Science and Technology Conference, Sydney, Australia, November 2003 in IMSTEC 2003, ed R. Ben Aim, AWA-UNESCO Membrane Centre, Sydney, Australia, pp. 1-7.
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Shon, H., Vigneswaran, S., Ngo, H.H. & Kim, I.S. 2003, 'Effect of high rate Pre-Treatment on Nanofiltration Systems in Wastewater Reuse', IWA Asia-Pacific Regional Conference, Bangkok, Thailand, October 2003 in ASIAN WaterQual 2003, ed V. Sutthamandaw and S. Thevuthasan, IWA-Regional Publication, Bangkok, Thailand, pp. 1-9.
Guo, W., Vigneswaran, S., Ngo, H.H., Shon, H. & Shimohoki, S. 2003, 'Improving the Performance of a Crossflow Microfiltration in Tertiary Wastewater Treatment and Reuse By Specific Pre-Treatment Processes', IWA Asia-Pacific Regional Conference, Bangkok, Thailand, October 2003 in ASIAN WaterQual 2003, ed S. Shimohoki, IWA-Regional Publication, Bangkok, Thailand, pp. 1-8.
Shon, H., Vigneswaran, S., Ngo, H.H., Kim, D., Park, N.E., Jang, N.J. & Kim, I.S. 2003, 'Characterisation of Effluent Organic Matter (EFOM)Of Fouled Nanofilter (NF) Membranes', Fifth International Membrane Science and Technology Conference, Sydney, Australia, November 2003 in IMSTEC2003, ed D. H.Kim, J. Cho, N.E. Park, N. J. Jang, I.S. Kim, AWA-UNESCO Membrane Centre, Sydney, Australia, pp. 1-6.

Journal Articles

El Saliby, I., Erdei, L., McDonagh, A.M., Kim, J., Kim, J. & Shon, H. 2014, 'Co-doped mesoporous titania photocatalysts prepared from a peroxo-titanium complex solution', Materials Research Bulletin, vol. 49, no. 1, pp. 7-13.
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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 8C 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 8C. 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.
Tijing, L.D., Choi, J., Lee, S., Kim, S. & Shon, H. 2014, 'Recent progress of membrane distillation using electrospun nanofibrous membrane', Journal Of Membrane Science, vol. 453, pp. 435-462.
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Ary Subagia, I., Tijing, L.D., Kim, Y., Kim, C., Vista IV, F. & Shon, H. 2014, 'Mechanical performance of multiscale basalt fiber-epoxy laminates containing tourmaline micro/nano particles', Composites Part B: Engineering, vol. 58, pp. 611-617.
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Ary Subagia, I., Kim, Y., Tijing, L.D., Kim, C. & Shon, H. 2014, 'Effect of stacking sequence on the flexural properties of hybrid composites reinforced with carbon and basalt fibers', Composites Part B: Engineering, vol. 58, pp. 251-258.
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Park, C., Kim, E., Tijing, L.D., Amarjargal, A., Pant, H., Kim, C. & Shon, H. 2014, 'Preparation and characterization of LA/PCL composite fibers containing beta tricalcium phosphate (-TCP) particles', Ceramics International, vol. 40, no. 3, pp. 5049-5054.
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tijing, L.d. & Shon, H. 2014, 'Facile in situ growth of highly monodispersed Ag nanoparticles onelectrospun PU nanofiber membranes: Flexible and high efficiencysubstrates for surface enhanced Raman Scattering', Applied Surface Science, vol. 308.
Tijing, L.D. & Shon, H. 2014, 'Preparation andcharacterizationofLA/PCLcomposite fibers containing', CERAMICS international, vol. 40.
Tijing, L.D. & Shon, H. 2014, 'Mechanical performance of multiscale basalt fiber+epoxy laminates', Composites: Part B, vol. 58.
Phuntsho, S. & Shon, H. 2014, 'Boron transport through polyamide-based thin film composite forward', Desalination, vol. 340.
Phuntsho, S. & Shon, H. 2014, 'Coagulation by titanium tetrachloride for fulvic acid removal:', Desalination, vol. 335.
Shon, H. & Tijing, L.D. 2014, 'Effect of stacking sequence on the flexural properties of hybrid', Composites: Part B, vol. 58.
Shon, H. 2014, 'Influence of different ion types and membrane orientations on the', desalination, vol. 344.
Shahid, M., El Saliby, I., McDonagh, A.M. & Shon, H. 2014, 'Photodesorption of specific organic compounds from titanium', Desalination and Water Treatment, vol. 52.
Nateghi Ghasemian Nejad, F., Shon, H. & Khabbaz, H. 2014, 'Development of a new poly silicate ferric coagulant', Desalination and Water Treatment, vol. 52.
Shon, H. & Phuntsho, S. 2014, 'Removal of natural organic matter by titanium tetrachloride:', Journal of Environmental Management, vol. 134.
Shon, H. 2014, 'Role of wetland organic matters as photosensitizer for degradation ofmicropollutants and', Journal of Hazardous Materials, vol. 276.
Shon, H. 2014, 'Combined organicandcolloidalfoulinginforwardosmosis:', Journal of Membrane Science, vol. 460.
Tijing, L.D. & Shon, H. 2014, 'Recentprogressofmembranedistillationusingelectrospun', Journal of Membrane Science, vol. 453.
Phuntsho, S. & Shon, H. 2014, 'Osmoticequilibriumintheforwardosmosisprocess:Modelling,', Journal of Membrane Science, vol. 453.
Shon, H. 2014, 'Titania produced from Ti-salt flocculated sludge: Photocatalytic activity under solar light', Journal of Nanoscience and Nanotechnology, vol. 14.
El Saliby, I., McDonagh, A.M. & Shon, H. 2014, 'Co-doped mesoporous titania photocatalysts prepared from a', Materials Research Bulletin, vol. 49.
Shon, H. & Phuntsho, S. 2014, 'Coagulation and sludge recovery using titanium tetrachloride', Separation and Purification Technology, vol. 130.
Phuntsho, S., Lotfi, F. & Shon, H. 2014, 'Membrane scaling and flux decline during', Water research, vol. 57.
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.
Shon, H. & Chekli, C. 2014, 'NOx removal on mortar mixed with titania produced from Ti-salt flocculated sludge', Journal of Industrial and Engineering Chemistry, vol. 20, pp. 3851-3856.
Shon, H. 2014, 'Influence of different ion types and membrane orientations on the forward osmosis performance', Desalination, vol. 344.
Shon, H. & Tijing, L.D. 2014, 'Silicone coating of nitinol stent wires by electrospinning Catheter deployment test', Digest Journal of Nanomaterials & Biostructures, vol. 9, no. 1, pp. 1-6.
Shon, H., Phuntsho, S. & Lotfi, F. 2014, 'Membrane scaling and flux decline during fertiliser-drawn forward osmosis desalination of brackish groundwater', Water Research, vol. 57.
Shon, H., Majeed, T., Lotfi, F., Sahebi, S., Kim, J. & Phuntsho, S. 2014, 'Fertilizer-drawn forward osmosis for irrigation of tomatoes', Desalination and Water Treatment, vol. 201.
Shon, H., Vigneswaran, S. & Phuntsho, 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.
Shon, H., Majeed, T., Lotfi, F. & Phuntsho, S. 2014, 'Performances of PA hollow fiber membrane with the CTA flat sheet membrane for forward osmosis process', Desalination and Water Treatment, vol. 203.
Shon, H., El Saliby, I. & Vigneswaran, S. 2014, 'Sources, distribution, environmental fate and ecological effects of nanomaterials in wastewater streams', Critical Reviews in Environmental Science and Technology, vol. 255.
Shon, H., Kim, J., Phuntsho, S. & Lotfi, F. 2014, 'Comparative performance of 8040 spiral wound forward osmosis membrane modules with corrugated and medium spacer for desalination of brackish groundwater fertilizer draw solution', Desalination and Water Treatment, vol. 265.
Shon, H., Majeed, T., Sahebi, S., Kim, J. & Phuntsho, S. 2014, 'Influence of the process parameters on hollow fiber forward osmosis membrane performances', Desalination and Water Treatment, vol. 266.
Shon, H., Shahid, M. & McDonagh, A.M. 2014, 'Magnetised titanium dioxide (TiO2) for water purification: preparation, characterisation, and application', Desalination and Water Treatment, vol. 266.
Shon, H. & Tijing, L.D. 2014, 'Hybrid Multi-scale Basalt Fiber-epoxy Composite Laminate Reinforced with Electrospun Polyurethane Nanofibers Containing Carbon Nanotubes', Fibers and Polymers, vol. 15.
Shon, H., Tijing, L.D., Woo, Y. & Johir, M.A. 2014, 'A novel dual-layer bicomponent electrospun nanofibrous membrane for desalination by direct contact membrane distillation', Chemical Engineering Journal, vol. 256.
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.
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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).
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.
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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.
Jeong, S., Kim, S., Kim, C.M., Vigneswaran, S., Nguyen, T.V., Shon, H., Kandasamy, J.K. & Kim, I.S. 2013, 'A detailed organic matter characterization of pretreated seawater using low-pressure microfiltration hybrid systems', Journal Of Membrane Science, vol. 428, pp. 290-300.
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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 chromatography++mass 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.
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.
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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 using the same method, which indicates that these aggregates have a more compact structure.
Kim, J.B., Lee, K.W., park, s.m., Shon, H., Shahid, M., El Saliby, I., Lee, W.E., kim, g.j. & kim, j.h. 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.
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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.
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.
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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.
Shon, H., Phuntsho, S., Chaudhary, D.S., 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.
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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.
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.
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A pilot-scale municipal wastewater reclamation system using combined coagulation and disk filtration (CC+DF), 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 CC+DF 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 CC+DF 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.
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.
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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 coagulation+ultra filtration (C+UF) 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.
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.
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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 m). 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.
Zhao, Y., Gao, B., Qi, Q., Wang, Y., Phuntsho, S., Kim, J.H., 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.
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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
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.
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-
Kus, B.G., Kandasamy, J.K., 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.
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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.
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.
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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 chromatography+organic carbon detector (LC+OCD). 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.
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.
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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.
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.
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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.
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.
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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.
Zhao, Y., Phuntsho, S., Gao, B., Huang, X., Qi, Q., Wang, Y., Kim, J. & Shon, H. 2013, 'Preparation and characterization of novel polytitanium tetrachloride coagulant for water purification', Environmental Science & Technology, vol. 47, no. 22, pp. 12966-12975.
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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.
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.
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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.
Fam, W.A., Phuntsho, S., Shon, H. & Lee, J.H. 2013, 'Performance comparison of thin-film composite forward osmosis membranes', Desalination and Water Treatment, vol. 51, no. 31-33, pp. 6274-6280.
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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.
Kus, B.G., Kandasamy, J.K., 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.
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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 0.3+0.4 NTU, below the ADWG limit of 1 NTU.
Zhao, Y., Gao, B., Shon, H., Wang, Y., Kim, J.H., Yue, Q. & Bo, X.Y. 2012, 'Anionic polymer compound bioflocculant as a coagulant aid with aluminum sulfate and titanium tetrachloride', Bioresource Technology, vol. 108, pp. 45-54.
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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, X.Y. & 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.
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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.
El Saliby, I., Okour, Y., Shon, H., Kandasamy, J.K., Lee, W.E. & 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.
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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.
Phuntsho, S., Shon, H., Majeed, T., El Saliby, I., Vigneswaran, S., Kandasamy, J.K., Hong, S. & Lee, S. 2012, 'Blended Fertilizers as Draw Solutions for Fertilizer-Drawn Forward Osmosis Desalination', Environmental Science & Technology, vol. 46, pp. 4567-4575.
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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., Shon, H., Hong, S., Lee, S., Vigneswaran, S. & Kandasamy, J.K. 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.
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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
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.
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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, T.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.
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Deep bed filtration has traditionally been used as a pretreatment in seawater desalination. The performance of contact flocculation++filtration (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 (0.5++3.0mg Fe3+/L) and rapid mixing times (1.7++14.4 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).
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.
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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.
Kus, B.G., Johir, M.H., Kandasamy, J.K., 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.
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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 0.79++0.99 NTU which were well below the 5 NTU ADWG (2004) limit [1]. 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) [1] 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, B.G., Kandasamy, J.K., 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.
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
Chekli, L., Phuntsho, S., Shon, H., Vigneswaran, S., Kandasamy, J.K. & Chanan, A.P. 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.
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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
El Saliby, I., Shahid, M., McDonagh, A.M., 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.
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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.
Phuntsho, S., Vigneswaran, S., Kandasamy, J.K., 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.
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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 25-C to 35-C while this rise is 2.3% from 25-C to 45-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 25-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.
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.
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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.
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.
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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.
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.
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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 on+ line 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.
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, no. NA, pp. 181-188.
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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.
Zhao, Y., Gao, B., Cao, B.C., Yang, Z., Yue, Q., Shon, H. & Kim, J.H. 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.
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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 +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., Shon, H., Cao, B.C. & Kim, J.H. 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.
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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 (801 m) 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.
El Saliby, I., Shon, H., Kandasamy, J.K. & Kim, J. 2011, 'Synthesis, characterisation and separation of photoreactive Hydrogen-titanate nanofibrous channel', Separation and Purification Technology, vol. 77, no. 2, pp. 202-207.
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Australia is the world's largest wool producing country, accounting for about 25++30% 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 +C was utilised to prepare the nanofibrous channel. Anatase undoped nanofibrous (average nanofibre diameter = 44 nm) channel of around 50 min length and an average diameter of 9.5 mwere 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.
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.
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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.
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.
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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.
Kim, J., Okour, Y., Yang, H., Kim, J.B. & 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.
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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 -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 -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.
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.
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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).
Liu, H., Shon, H., Sun, X., Vigneswaran, S. & Nan, H. 2011, 'Preparation and characterization of visible light responsive Fe2O3+TiO2 composites', Applied Surface Science, vol. 257, no. 13, pp. 5813-5819.
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In this studywepresent the effects of iron oxide (Fe2O3) on titanium dioxide (TiO2) in synthesising visiblelight reactive photocatalysts. A Fe2O3++TiO2 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 Fe2O3++TiO2 composites were investigated. The results showed that -Fe2O3 and anatase TiO2 were present in the composites. The Fe2O3++TiO2 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.
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.
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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.
Kim, J., Cho, D.L., 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.
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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.
El Saliby, I., Erdei, L., Shon, H., Kim, J.B. & Kim, J. 2011, 'Preparation and characterisation of mesoporous photoactive Na-titanate microspheres', Catalysis Today, vol. 164, no. 1, pp. 370-376.
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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 25+C and 80 +C. The as-prepared powders were characterised by X-ray diffraction, N2 adsorption++desorption measurements and scanning electron microscope/energy dispersive X-ray spectroscopy. The as-prepared microspheres were calcined at 550 +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 +C, whereas spherical aggregation of nanofibres was detected in powders produced at 80 +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.
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.
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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.
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.
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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.
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.
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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 8.7++19.8%. 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.
Okour, Y., Shon, H., Liu, H., Kim, J.B. & Kim, J.H. 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.
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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 -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.
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.
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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.
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.
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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-N++Ag 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.
Na, S., Shon, H., Kim, J.B., Park, H.J. & 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.
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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 10++15 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.
Kus, B.G., Kandasamy, J.K., 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.
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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.
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.
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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, UV++vis spectra and high performance liquid chromatography of 2,4-D before and after photodegradation.
Lee, S., Kim, K., Shon, H., Kim, S.H. & Cho, J. 2011, 'Biotoxicity Of Nanoparticles: Effect Of Natural Organic Matter', Journal of nanoparticle Research, vol. 13, no. 7, pp. 3051-3061.
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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.
Ho, D., Vigneswaran, S., Ngo, H.H., Shon, H., Kandasamy, J.K., Chang, Y. & Chang, J.S. 2011, 'Photocatalysis of Trimethoprim (TRI) in Water', Sustainable Environment Research (SER), vol. 21, no. 3, pp. 149-154.
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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.
Shon, H., Okour, Y., El Saliby, I., Kim, J.B. & 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.
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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.
Singh, G., Kandasamy, J.K., 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.
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.
Kus, B.G., Kandasamy, J.K., Vigneswaran, S., Shon, H. & Areerachakul, N. 2011, 'Water quality of membrane filtered rainwater', Desalination and Water Treatment, vol. 32, pp. 208-213.
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.
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.
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 AM++2:00 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.
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.
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.
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.
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 ++m 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.
Zhao, Y., Gao, B., Shon, H., Wang, Y., Kim, J.H. & 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.
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Characteristics of flocs formed by charge neutralization and sweep coagulation using titanium tetrachloride (TiCl4) were investigated with humic acid++kaolin 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.
Zhao, Y., Gao, B., Shon, H., Kim, H.J., 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.
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The floc strength and regrowth properties of TiCl4, FeCl3, and Al2 SO4)3 were comparatively evaluated using humic acid++kaolin 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., Rong, H., Shon, H., Kim, H.J., 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.
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Coagulation of humic acid++kaolin 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.
Shon, H., Vigneswaran, S., Kandasamy, J.K., 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.
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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
Chinu, K.J., Johir, M.H., Vigneswaran, S., Shon, H. & Kandasamy, J.K. 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.
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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 (1510++1180 Da), while the small molecular weights (less than 530 Da) were not removed.
Lee, J., Johir, M.H., Chinu, K.J., Shon, H., Vigneswaran, S., Kandasamy, J.K., Kim, C.W. & Shaw, K. 2010, 'Novel pre-treatment method for seawater reverse osmosis: Fibre media filtration', Desalination, vol. 250, no. 2, pp. 557-561.
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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 (++P), 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
Kus, B.G., Kandasamy, J.K., 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.
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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, B.G., Kandasamy, J.K., 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.
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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.
Na, S.H., Shon, H., Kim, J.B., Park, H.J., Cho, D.L., El Saliby, I. & Kim, J.H. 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.
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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 -C) and pH 11 (60 8 -C), respectively. Flocculation was carried out using a Ti-salt flocculant and the collected sludge was dewatered and incinerated at 600 -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 l++1. 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, J.B. & Kim, J.H. 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.
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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.
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.
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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.
Ren, X., Shon, H., Jang, N., Lee, Y.G., Bae, M., lee, J., Cho, K. & Kim, I.S. 2010, 'Novel membrane bioreactor (MBR) coupled with a nonwoven fabric filter for household wastewater treatment', Water Research, vol. 44, no. 3, pp. 751-760.
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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 0.3++1.9 ++ 1012 m/kg. Due to the low F/M ratio (0.04++0.10 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.
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.
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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.
Chinu, K.J., Vigneswaran, S., Erdei, L., Shon, H., Kandasamy, J.K. & Ngo, H.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.
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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 (1510++1180 Da), while the small molecular weights (less than 530 Da) were not removed.
Park, K.H., Shim, W.G., Shon, H., Lee, S.G., Ngo, H.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.
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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 -+ ) 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 ACs++ adsorption kinetic of acetaldehyde.
Shon, H., Vigneswaran, S., El Saliby, I., Okour, Y., Kim, I.S., Cho, J., Park, H.J., Kim, J.B. & 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.
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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 ++sacrificial reagent+ 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, H., Phuntsho, S., Vigneswaran, S., Kandasamy, J.K., Nghiem, L.D., Kim, G., Kim, J.B. & 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.
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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 600-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.
El Saliby, I., Shon, H., Okour, Y., Vigneswaran, S., Senthilnanthanan, M. & Kandasamy, J.K. 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.
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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.
Shon, H., Phuntsho, S., Vigneswaran, S., Kandasamy, J.K., Kim, J.B., Park, H.J. & Kim, I.S. 2010, 'PVDF-TiO2 Coated microfiltration membranes: preparation and characterization', Membrane Water Treatment, vol. 1, no. 3, pp. 193-206.
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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%).
Chanan, A.P., Vigneswaran, S., Kandasamy, J.K. & Shon, H. 2010, 'Chemical-assisted physico-biological water mining system', Institution of Civil Engineers. Proceedings. Water Management, vol. 163, no. 9, pp. 469-474.
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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.
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.
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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
Kim, S.H., Shon, H. & Ngo, H.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.
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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
Senthilnanthan, M., Ho, D., Vigneswaran, S., Ngo, H.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.
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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 +C, the degradation efficiencies moderately changed from 65 to 90%. However, the effect of calcination duration was marginal on the photodegradation of MSM.
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.
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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.
Kim, J.B., Park, H.J., Shon, H., Cho, D.L., 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.
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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, J.K., Seol, D., Shon, H., Kim, G. & Kim, J.K. 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.
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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
Nguyen, T.V., Vigneswaran, S., Ngo, H.H., Shon, H. & Kandasamy, J.K. 2009, 'Arsenic removal by a membrane hybrid filtration system', Desalination, vol. 236, no. 1-3, pp. 363-369.
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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.
Shon, H., Vigneswaran, S., Zareie, H.M., Ben Aim, R., Lee, E., lee, J., Cho, J. & Kim, I.S. 2009, 'Physico-chemical pretreatment to Seawater Reverse Osmosis (SWRO): Organic Characterization and Membrane Autopsy', Desalination, vol. 236, no. 1 - 3, pp. 282-290.
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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.
Shon, H., Okour, Y., El Saliby, I., Park, J., Cho, D.L., Kim, J.B., Park, H.J. & Kim, J.H. 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.
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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.
Mohammed Abdul, J., Chinu, K.J., 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.
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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 (CFS+MFI). In CFS+MFI, 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 CFS+MFI 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 CFS+MFI 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 CFS+MFI indices. It yielded useful insights in understanding the effect of MW on MFI and CFS+MFI and fouling propensity of the feed.
Mohammed Abdul, J., Vigneswaran, S., Shon, H., Areerachakul, N. & Kandasamy, J.K. 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.
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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.
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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 60+67% 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.
Lee, J., Johir, M.A., Chinu, K.J., Shon, H., Vigneswaran, S., Kandasamy, J.K., Kim, C.W. & Shaw, K. 2009, 'Hybrid filtration method for pre-treatment of seawater reverse osmosis (SWRO)', Desalination, vol. 247, no. 1-3, pp. 15-24.
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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%.
Chinu, K.J., Johir, M.H., Vigneswaran, S., Shon, H. & Kandasamy, J.K. 2009, 'Biofilter as pretreatment to membrane based desalination: Evaluation in terms of fouling index', Desalination, vol. 247, no. 1-3, pp. 77-84.
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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 10++15 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 0.2++0.3 NTU and 0.28++0.31 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., Kandasamy, J.K. & Kim, I.S. 2009, 'Desalination plants in Australia, review and facts', Desalination, vol. 247, no. 1-3, pp. 1-14.
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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 project++the 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, J.K., Zareie, H.M., Kim, J.B., Cho, D.L. & Kim, J.H. 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.
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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 600-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 (+-Fe2O3). The majority of gaseous acetaldehyde with TiO2-WO and Ca/TiO2 for photocatalytic activity was completely removed within 40 minutes under UV irradiation.
Aryal, R., Lebegue, J., Shon, H., Vigneswaran, S., Kandasamy, J.K. & Grasmick, A. 2009, 'Temporal variation of foulant characteristics in membrane bioreactor', Desalination and Water Treatment, vol. 6, no. 1-3, pp. 69-73.
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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 h 1 m 2 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 h 1m 2 and 2 m3 h 1 m 2 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.
El Saliby, I., Okour, Y., Shon, H., Vigneswaran, S., Kandasamy, J.K. & Kim, J.H. 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.
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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.
Lee, B., Kim, S.H., Shon, H., Vigneswaran, S., Kim, S.H., Cho, J., Kim, I., Choi, K., Kim, J.K., Park, H.J. & Kim, J.K. 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.
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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.
Shon, H., Cho, D.L., Na, S.H., Kim, J.K., Park, H.J. & Kim, J.K. 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.
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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.
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.
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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.
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.
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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.
Johir, M.H., Chinu, K.J., 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.
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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.
Okour, Y., El Saliby, I., Shon, H., Vigneswaran, S., Kim, J.H., Cho, J. & Kim, I.S. 2009, 'Recovery of sludge produced from Ti-salt flocculation as pretreatment to seawater reverse osmosis', Desalination, vol. 247, no. 1-3, pp. 53-63.
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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., Puntsho, S., Chon, K., Aryal, R., Vigneswaran, S., Kim, I.S. & 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.
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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.
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.
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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.
Shon, H., Vigneswaran, S., Kandasamy, J.K., Kim, J.B., Park, H.J., Choi, S. & Kim, J.H. 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.
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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.
Shon, H., Kim, S.H., Vigneswaran, S., Ben Aim, R.M., Lee, S. & Cho, J. 2009, 'Physicochemical Pretreatment Of Seawater: Fouling Reduction And Membrane Characterisation', Desalination, vol. 238, no. 1-3, pp. 10-21.
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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 MFI+UF 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 MFI+UF experiments was made in terms of contact angle, zeta potential, functional group and microscopy.
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.
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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 (30 40%) and polysaccharides (30 40%), with 2 3 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.
Shon, H., Vigneswaran, S., Kandasamy, J.K. & Shim, W.G. 2008, 'Ultraflitration Of Wastewater With Pretreatment: Evaluation of Flux Decline Models', Desalination, vol. 231, no. 1-3, pp. 332-339.
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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, 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.
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An integrated photocatalysis+membrane 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.
Kim, S., Ngo, H.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.
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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 Langmuir+Hinshelwood (L+H) 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.
Sabina, L., Kus, B.G., Shon, H. & Kandasamy, J.K. 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.
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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
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.
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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., Phuntsho, S., Okour, Y., Cho, D.L., S, K.K., Li, J.H., Na, S.H., Kim, J.B. & Kim, J.H. 2008, 'Visible light responsive titanium dioxide (TiO2)', Journal of the Korean Industrial and Engineering Chemistry, vol. 19, no. 1, pp. 1-16.
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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.
Lim, G.T., Kim, K.H., Kim, K.S., Li, H., Song, S.j., Shon, H. & Cho, D.L. 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.
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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., Vigneswaran, S., Kim, I.S., Cho, J., Kim, G., Kim, J.K. & 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.
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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, J.K. & Ngo, H.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.
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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.H., Kim, J.K. & Kandasamy, J.K. 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.
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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
Kim, S.H. & 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.
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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, P.J., Vigneswaran, S. & Ngo, H.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.
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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
Vigneswaran, S., Shon, H., Kandasamy, J.K. & Shim, W.G. 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.
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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., Vigneswaran, S., Kim, J.H. & Ngo, H.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.
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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. & Ngo, H.H. 2006, 'Effect of partial flocculation and adsorption as pretreatment to ultrafiltration', Aiche Journal, vol. 52, no. 1, pp. 207-216.
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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.
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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.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.
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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
Smith, P.J., Shon, H., Vigneswaran, S., Ngo, H.H. & Nguyen, H.T. 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.
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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
Shon, H., Kim, S.H., 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.
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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
Areerachakul, N., Shon, H., Vigneswaran, S. & Ngo, H.H. 2006, 'Photocatalytic hybrid system in degradation of herbicide (metsulfuron-methyl)', Water Science & Technology: Water Supply, vol. 6, no. 2, pp. 109-114.
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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, N.J., Shon, H., Ren, X., Vigneswaran, S. & Kim, I.S. 2006, 'Characteristics of Bio-Foulants in the Membrane Bioreactor', Desalination, vol. 200, no. 1-3, pp. 201-202.
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Shon, H., Vigneswaran, S., Ngo, H.H., Johnston, A.J., Kim, I.S. & 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.
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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.
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.
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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)
Shon, H., Vigneswaran, S., Ngo, H.H., Kim, I.S. & Ben Aim, R.M. 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, H., Vigneswaran, S., Ngo, H.H. & Kim, J.K. 2005, 'Chemical coupling of photocatalysis with flocculation and adsorption in the removal of organic matter', Water Research, vol. 39, no. 12, pp. 2549-2558.
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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.H., Kim, I. & Ben Aim, R.M. 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.
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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.H. & Aim, R.B. 2005, 'Is semi-flocculation effective as pretreatment to ultrafiltration in wastewater treatment?', Water Research, vol. 39, no. 1, pp. 147-153.
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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., Ben Aim, R.M., Ngo, H.H., Kim, I.S. & 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.
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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.J., Ngo, H.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.
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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., Kim, I.S., Cho, J. & Ngo, H.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.
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Shon, H., Vigneswaran, S., Kim, I.S., Cho, J. & Ngo, H.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.
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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., Guo, W., Vigneswaran, S., Ngo, H.H. & Kim, I.S. 2004, 'Effect of flocculation in membrane-flocculation hybrid system in water reuse', Separation Science And Technology, vol. 39, no. 8, pp. 1871-1883.
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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.
Vigneswaran, S., Shon, H., Boothanon, H., Ngo, H.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.
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Hoang, T., Shon, H., Chaudhary, D.S., Vigneswaran, S. & Ngo, H.H. 2004, 'Granular Activated Carbon (GAC) Biofilter For Low Strength Wastewater Treatment', Fluid/Particle Separation Journal, vol. 16, no. 2, pp. 185-191.
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