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Dr Wenshan Guo

Image of Wenshan Guo
Senior Lecturer, School of Civil and Environmental Engineering
Core Member, CTWW - Centre for Technology in Water and Wastewater Treatment
PhD (UTS)
Member, Australian Water Association
Member, International Water Association
 
Phone
+61 2 9514 2739

Research Interests

Dr. Guo's research focuses on the innovative water and wastewater treatment and reuse technologies. Her expertise and practical experience cover the areas of water and wastewater engineering such as membrane technologies (e.g. membrane bioreactor, microfiltration, membrane hybrid system, and PAC-submerged membrane bioreactor etc.), advanced biological wastewater treatment technologies (e.g. suspended growth reactors and attached growth reactors), and physico-chemical separation technologies (e.g. adsorption, column, and flocculation). She also has strong ability to work in solid waste management, life cycle assessment, and desalination.

Can supervise: Yes

Chapters

Nghiem, L.D., Hai, F.I., Price, W.E., Wickham, R., Ngo, H.H. & Guo, W. 2017, 'By-products of Anaerobic Treatment: Methane and Digestate From Manures and Cosubstrates' in Current Developments in Biotechnology and Bioengineering: Biological Treatment of Industrial Effluents, Elsevier, THe Netherlands, pp. 469-484.
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© 2017 Elsevier B.V. All rights reserved.Anaerobic digestion is a widely used and probably the most sustainable technique for biogas production and nutrient recovery from manure. This chapter describes the process of anaerobic digestion of manure and other cosubstrates with a specific focus on biogas and digestate utilization. Biogas purification is one of the most significant bottlenecks to fully realizing the range of biogas utilization for not just energy production but also other forms of beneficial usages. Thus, biogas purification techniques are discussed in detail in this chapter. Digestate from manure is an excellent biofertilizer and can be applied using the same equipment designed for liquid fertilizer. Previous studies corroborated in this chapter highlight the importance of quality control and digestate application practice particularly when manure is codigested with other cosubstrates or the digestate is used on a different farm.
Guo, W., Ngo, H.H., Tram Vo, T.P., Nghiem, I.D. & Hai, F.I. 2016, 'Aerobic Treatment of Effluents from the Aquaculture Industry' in Ngo, H.H. (ed), Current Developments in Biotechnology and Bioengineering Biological Treatment of Industrial Effluents, Elsevier, UK, pp. 35-77.
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Chapters in this volume review the most recent developments and perspectives at different environmental cleanup operation scales.
Ngo, H., Guo, W. & Chen, Z. 2014, 'New submerged membrane bioreactors (SMBRs) for sustainable water' in Singh, R.S., Pandey, A. & Larroche, C. (eds), Advances in Industrial Biotechnology, IK International Publishing House Pvt. Ltd., India, pp. 393-411.
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To ensure a stable and reliable operation of MBR in wastewater treatment, it is vital important to exploit and develop novel advanced system configurations as well as low cost and environmental friendly materials in controlling membrane fouling and reducing contaminant loading. The enhanced system performance, extended service life of membrane, and reduced operational cost can significantly contribute to long-term sustainable development in water resources. Compared with conventional SMBR approach, the modified SMBR systems, including ASMBR, SSMBR, integrated SMBR and GACS-FBBR, achieved more desirable outcomes in organic and nutrient removal and exhibited lower TMP development. While PAC in ASMBR can increase the organic removal, mitigate membrane fouling and enhance permeate flux by simultaneous functions of adsorption and biodegradation on its surface, the porous media (e.g., sponge and NB) addition to SMBR can be an excellent solution for additional nutrient removal improvement. It is worth noting that GBF can also play important roles for enhancing microbial activity and minimizing membrane fouling. Furthermore, both the laboratory and pilot scale studies on GACS-FBBR confi rmed that this hybrid system can be a promising pre-treatment for MBR, owing to its success in treating organics and nutrients along with the membrane fouling control.
Guo, W. & Ngo, H. 2012, 'Membrane Processes for Wastewater Treatment' in Zhang, T.C., Surampalli, R.Y., Vigneswaran, S., Tyagi, R.D., Ong, S.L. & Kao, C.M. (eds), Membrane Technology and Environmental Applications, American Society of Civil Engineers, USA, pp. 169-216.
Nowadays, continued population growth and economic development have contributed to increasing demand on water supplies, while multipurpose water use has let to deteriorating water quality by introducing chemical or biological contaminants to receiving waters. Although governments and water authorities have proclaimed more stringent discharge regulations together with increased wastewater disposal costs to protect human and environmental health, wastewater treatment has become ever more crucial and indispensable in order to preserve the diminishing water resources and minimize adverse impacts on our ecosystem. Over the last century various methods and technologies have been developed and applied to remove solids, organic pollutants and nutrients from wastewater. Wastewater treatment involves the combination of various physical, chemical and biological processes and operations (Table 6.1). In general, conventional wastewater treatment processes can successfully remove the majority of degradable organics and suspended solids found in wastewaters. However, to further provide a sufficient level of treatment to wastewater streams and to remove specific contaminants, membrane seperation technology has been emerged as an alternative and innovative treatment technology and plays an important role in global water market. This chapter gives an extensive and up-to-date review of membrane separation technologies (e.g.,microfiltration (MF), ultrafiltration (UP), nanofiltration (NP) and reverse osmosis (RO) in wastewater treatment with specific attention to various membranes, treatment processes and configurations, and their practical applications.
Ngo, H., Guo, W. & Vigneswaran, S. 2012, 'Membrane Processes for Water Reclamation and Reuse' in Zhang, T.C., Surampalli, R.Y., Vigneswaran, S., Tyagi, R.D., Ong, S.L. & Kao, C.M. (eds), Membrane Technology and Environmental Applications, American Society of Civil Engineers, USA, pp. 239-275.
Water reclamation and reuse is being increasingly emphasized as a strategy for rational use of limited freshwater and as a means of safeguarding the deteriorating aquatic environment due to wastewater disposal. Membrane technology is playing a vital role in augment our water supplies and is essential for sustainable production of clean water. This chapter gives a comprehensive review of technological development train of wastewater treatment, as well as the detailed perfonnance of advanced membrance processes in municipal wastewater reclamation and reuse. The technological and economic feasibility of different membrane-based technologies compared to conventional treatment processes is also elucidated in this chapter.
Guo, W., Ngo, H. & Vigneswaran, S. 2012, 'Fouling Control of Membranes with Pretreatment' in Zhang, T.C., Surampalli, R.Y., Vigneswaran, S., Tyagi, R.D., Ong, S.L. & Kao, C.M. (eds), Membrane Technology and Environmental Applications, American Society of Civil Engineers, USA, pp. 533-580.
The impediment of the membrane technology is a fouling problem and consequently higher operating and membrane relacement cost. Pretreatment is very important for developing the best treatment process train to secure better membrane treatability and producing acceptable effluent qualities. This chapter addresses the state of the art pretreatment techniques and their application to low pressure (MF/UF) and high pressure (NF/RO) memrances in water and wastewater treatment as well as desalination. The impact of different pretreatment processes on membrane performance and membrane fouling control have been extensively reviewed.
Guo, W., Ngo, H. & Vigneswaran, S. 2012, 'Enhancement of Membrane Processes with Attached Growth Media' in Zhang, T.C., Surampalli, R.Y., Vigneswaran, S., Tyagi, R.D., Ong, S.L. & Kao, C.M. (eds), Membrane Technology and Environmental Applications, American Society of Civil Engineers, USA, pp. 603-634.
The consumption of limited waste resources together with the need to comply with ever more stringent water quality standards, and the need to reuse water are the main impetus for the intensification of existing conventional water treatment processes. Moreover, current and impending legislation on wastewater treatment effluent has also led to the need for improved treatment processes capable of removing higher percentages of nutrients, suspended solids, bacteria, etc. (Kramne et al., 2005). During the last decades, the interest in the use of membrane technology has emerged in wastewater treatment as well as drinking water and process water production. This growth can be explained by a combination of (a) growing demand for water with high quality, (b) growing pressure to reuse wastewater, (b) better realibility and integrity of the membranes, (d) lower prices of membranes due to enhanced use, and (e) more stringent standards, e.g., in the drinking water industry (van de Bruggen et al., 2008). Therefore, membrane techniques (e.g., microfiltration (MF), ultrafiltration (DF), nanofiltration (NF) and reverse osmosis (RO)) in general and mebrance bioreactors (MBRs) in particular have been widely applied to wastewater reclamation and reuse for simultaneous organic and nutrient removal. Normally, there are two ways to begin water reuse: either retrofitting the current wastewater treatment plant (WWTP) facilities or constructing extra advanced processes after secondary treatment. Biological nutrients removal (BNR) processes modifying the current conventional WWTP is a typical example of retrofitting, while membrane filtration, carbon adsorption and ozonation are typically used for extra-installation the advanced treatment of secondary effluent (Baek and Chang, 2009). Especially, as eutrophication of the aquatic environment caused by nitrogen and phosphorus present in discharged effluent has become an unavoidable concern, the development of cost-effective and efficient BN...
Guo, W. 2009, 'Assessment methodologies for water reuse scheme and technology' in Vigneswaran, S. (ed), Water and Wastewater Treatment Technologies, EOLSS (Encyclopaedia of Life Support Systems) Publications, Oxford, UK, pp. 279-320.
This chapter illustrates the most basis assessment methodologies as decision support system and assessment framework for water reuse scheme and technology evaluation. It includes the analyses of life cycle, material flow, ecological footprint, health risk, energy consumption and economic and social impact in order to form rational concepts and approaches towards a comprehensive assessment method for water reuse.
Guo, W. 2009, 'Applied technologies in municipal solid waste landfill leachate treatment' in Vigneswaran, S. (ed), Water and Wastewater Treatment Technologies, EOLSS (Encyclopaedia of Life Support Systems) Publications, Oxford, UK, pp. 199-257.
This chapter illustrates the municipal solid waste landfillâs characteristics and discharge standard, its pollution problems and environmental impacts, and its typical applied solution technologies. The applied treatment technologies are discussed based on two main catalogues of conventional and advanced technologies. The conventional technologies include: (i) physico-chemical (coagulation-flocculation, chemical precipitation, activated carbon adsorption, ion exchange, membrane filtration, chemical oxidation etc.); (ii) biological (aerobic or anaerobic conditions, suspended-growth or attached-growth conditions, and fixed-bed or moving-bed conditions). The advanced technologies are introduced to three integration groups of (i) physicochemical, (ii) multi-biological, and (iii) physicochemical-biological processes.
Guo, W. 2009, 'Specific options in biological wastewater treatment for reclamation and reuse' in Vigneswaran, S. (ed), Water and Wastewater Treatment Technologies, EOLSS (Encyclopaedia of Life Support Systems) Publications, Oxford, UK, pp. 308-378.
This chapter focuses on a number of specific biological treatment technologies as options to wastewater reclamation with specific reference to concepts, treatment processes and configurations and its performance. These biological technologies will be classified and discussed in two main categories of non-membrane biological and membrane biological treatment systems.

Conferences

Guo, W. 2011, 'Risk control and environment based assessment of recycled water schemes in australia', CESE 2011, The Fourth Annual Conference on the Challenges in Environmental Science adn Engineering, CESE Conference Committee, Tainan, Taiwan, pp. 4-85.
Guo, W. 2011, 'Optimisation of an integrate sponge - granular activated carbon fluidized bed bioreactor in secondary sewage treatment', CESE 2011, The Fourth Annual Conference on the Challenges in Environmental Science and Engineering, CESE Conference Committee, Tainan City, Taiwan, pp. 75-76.
Guo, W. 2011, 'Impact assessment of extra discharges of organics and nutrients into aquatic systems by entropy calculation', CESE 2011, The Fourth Annual Conference on the Challenges in Environmental Science and Engineering, CESE Conference Committee, Tainan City, Taiwan, pp. 13-94.
Xing, W., Guo, W., Ngo, H., Listowski, A. & Cullum, P. 2008, 'Specific anaerobic fluidized bed bioreactors as pre treatment to microfilttration in domestic waste water treatment for re use', PROC. 6th Regional Symposium on Membrane Science & Technology, Regional Symposium on Membrane Science & Technology, Universiti Teknologi Malaysia, Thailand, pp. 1-8.
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Guo, W., Ngo, H., Palmer, C.G., Xing, W., Yen-Jung, H. & Listowski, A. 2008, 'Enhanced biological nutrient removal by a single stage sponge-submerged membrane bioreactor in waste water treatment for reuse', Proc.IWA Regional Conference, IWA Regional Conference, IWA, Moscow, pp. 168-173.
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Guo, W., Xing, W., Ngo, H., Hu, Y.A., Palmer, C.G. & Zhang, R. 2008, 'Enhancement of organics removal by an integrated non woven media biofilter-submerged membrane adsorption hybrid system', Proc. 6th Regional Symposium on Membrane Science & Technology, Regional Symposium on Membrane Science & Technology, Prince of Songkla University, Thailand, pp. 1-8.
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Listowski, A., Ngo, H., Guo, W., Vigneswaran, S. & Palmer, C.G. 2008, 'Assessment Framework of Urban Water Reuse Based on a Novel Integrated Water Cycle Concept', Proceedings of the IWA World Water Congress and Exhibition 2008, IWA World Water Congress, International Water Association (IWA), Vienna, Austria, pp. 1-8.
To achieve sustainability of the water reclamation and urban reuse technologies, it would be necessary to develop and apply comprehensive assessment methodology and processes that would consider critical elements of urban water cycle, sustainability criteria and appropriate performance assessment standards as an integrated framework. When trying to study the rationale behind the urban water reuse approaches from social, economic, technical and ecological point of view, the outcomes are often lacking cohesion and appropriate balance. The assessment methods are further complicated by the lack of consistency, specific and accurate information and methodologies, which ultimately impair the process. Taking into consideration complexity and uniqueness of the integrated water cycle concept, this paper introduces to a novel assessment framework. This enables to identify suitable assessment process consisting of logical steps and including relevant objectives, principles from which a broad selection of criteria s and performance indicators would be derived. The final step in the process would be focused on validation of the quantitative analysis and model preparation. A considerable effort would also be necessary to establish baseline indicators of sustainability and operational tools to evaluate performance of the urban water systems.
Ngo, H., Guo, W., Vigneswaran, S. & Xing, W. 2007, 'Potential of submerged membrane bioreactors for wastewater treatment and reuse', Proceedings of International Conference on Cleaner Technologies and Environmental Management, International Conference on Cleaner Technologies and Environmental Management, Allied Publishers Pvt. Ltd., India, pp. 800-805.
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The use of membrane bioreaetor (MBR) has been an increasing issue in replacing the conventional water and wastewater treatment processes to produce high quality treated water. In MBR systems design,the submergedmembranebioreactor (SMBR)can assist in significantlyreducingpower consumptionas the entire treatment activity (such as adsorption/biodegradation,liquid-solid separation, andsludgeaccumulationandwithdrawal)canbe carriedout in a singleunit. In this study, the performance of conventional 5MBR and non-eonventional submerged membrane adsorption bioreactor (SMABR) was evaluated in terms of organic and bacterial removal efficiencies,biomassgrowthvia specificoxygen uptake rate (SOUR) and mixed liquor suspendedsolids (MLSS), and membrane fouling through the development of transmembrane pressure (TMP) and sustainableflux.Theresults indicatethat both ofSMBRand5MBARproducedvery high effiuentquality. However,SMABRappeared to have a better performance as it achieved nearly 100%ofTOC andCOD removalswhile having lowerTMPdevelopment and higher SOUR,The MLSSkept constant (around 10 gIL) after 10 days operation in 5MBAR compared to about 4 gILofMLSS in 5MBR case. In order 10 enhancethe sustainableflux, an idea ofadding a predeterminedamountof spongeinto 5MBRreactor was proposedand tested, The results show that 10% of volume fraction of sponge addition could increase 2 folds of sustainablefluxofSMBRsystemat an air flow rate of9 L/min.
Dempsey, T., Ngo, H., Palmer, C.G. & Guo, W. 2007, 'Application of Life Cycle Analysis (LCA) to a Typical Nursery Industry in Australia', Proceedings of International Conference on Cleaner Technologies and Environmental Management, International Conference on Cleaner Technologies and Environmental Management, Allied Publishers Pvt. Ltd., India, pp. 15-20.
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Guo, W. 2006, 'Application of biological activated carbon for organic removal in wastewater reuse', . The Symposium of Centre of Excellence on Global Renaissance by Green Energy Revolution, Nagaoka University of Technology, Nagaoka, Japan.
In this study, both biological activated carbon (Powdered activated carbon (PAC) and granular activated carbon (GAC)) used in a submerged membrane â adsorption hybrid system (SMAHS) and a biological filtration system was evaluated for organic removal in wastewater reuse. The results indicated that the application of biological activated carbon in low strength wastewater treatment produced effluent of high quality that can be used for various reuse purposes. The adsorption and biological activity lead to a consistent effluent organic concentration over a long period of time. The submerged membrane adsorption hybrid system (SMAHS) was very effective in removing dissolved organic substances from the synthetic wastewater even with a low dosage of biological powdered activated carbon (BPAC). The adsorbed organics on the BPAC is biodegraded with time, and hence it creates sites for further adsorption of organics on the BPAC. The BPAC replacement in BPAC-MF reactor could stimulate both biological activity and adsorption, as well as optimize the operation of the hybrid system. Biological granular activated carbon (BGAC) consistently maintained an organic removal efficiency of 60% even with a shallow filter depth of 300 mm and after 42 days of operation. The growth of biomass onto BGAC experiments indicated that the attachment of biomass was quite consistent with about 85 mg/g GAC after 15 days in contact with synthetic wastewater. It was found that the amount of fixed biomass on filter media was proportionally related to biological dissolved oxygen consumption rate.
Guo, W. 2005, 'The membrane adsorption hybrid system in wastewater treatment and reuse', The 58th National Congress of Indian Institute of Chemical Engineers (CHEMCON-2005), Indian Institute of Technology (IIT), Delhi, India.
Guo, W. 2005, 'Enhancement of critical flux by pretreatment to a crossflow microfiltration in tertiary wastewater treatment', 1st IWA-ASPIRE Conference & Exhibition, IWA, Singapore.
In this study, the need of pretreatment of flocculation and adsorption on flux improvement was evaluated in terms of critical flux. Critical flux is defined as the maximum filtration rate, under which the membrane fouling does not occur during operation. The critical flux was experimentally evaluated for crossflow microfiltration (CFMF) with and without the pretreatment using biologically treated sewage effluent from a Sewage Treatment Plant in South Korea. The results indicate that the preflocculation could not enhance significantly the critical flux. However, the preadsorption led to a critical flux of more than 3 times higher than that of wastewater (200 L/m2.h). When both flocculation and adsorption were used as pretreatment, the critical flux was raised up to 1000 L/m2.h. Molecular weight distribution (MWD) analyses on the wastewater before and after pretreatment indicated that flocculation-adsorption as pretreatment was efficient to remove most of organic matter in this wastewater, which contains small and middle range MW molecules (250â780 Daltons). The Scanning Electron microscope (SEM) showed that membrane fouling during the critical flux experiments was mainly due to pore blocking and small particles deposit on the membrane surface.
Guo, W., Vigneswaran, S. & Ngo, H. 2004, 'A Rational Approach In Controlling Membrane Fouling Problems: Pretreatments to a submerged Hollow Fibre Membrane System', Water Environment - Membrane Technology Proceedings, IWA Specialty Conference, Water Environment-Membrane Technology, IWA, Seoul, Korea, pp. 517-524.
Guo, W., Vigneswaran, S., Ngo, H. & Ben Aim, R.M. 2004, 'Performance of a Submerged Membrane Adsorption Hybrid System (SMAHS) in Wastewater Treatment for Reuse', 4th World Water congress: innovations in Drinking Water Treatment, IWA World Water Congress, IWA, Marrakech, Morocco, pp. 1-8.
Chaudhary, D.S., Guo, W., Vigneswaran, S., Ngo, H. & Vigneswaran, B. 2003, 'Submerged Microfiltration: An Energy Efficient Process for Water Reuse', AWA Oz Water Convention and Conference, Australian Water Association Convention - Ozwater, AWA, Perth, Australia, pp. 1-9.
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Guo, W., Vigneswaran, S., Ngo, H. & Ben Aim, R.M. 2003, 'Evaluating the Efficiency of Pretreatment to Microfiltration: Using Critical Flux As a Performance Indicator', IMSTEC 2003, International Membrance Science and Technology Conference, AWA-UNESCO Membrane Centre, Sydney, Australia, pp. 1-6.
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Guo, W., Vigneswaran, S., Ngo, H., Shon, H. & Shimohoki, S. 2003, 'Improving the Performance of a Crossflow Microfiltration in Tertiary Wastewater Treatment and Reuse By Specific Pre-Treatment Processes', ASIAN WaterQual 2003, IWA Asia-Pacific Regional Conference, IWA-Regional Publication, Bangkok, Thailand, pp. 1-8.

Journal articles

Ahmed, M.B., Zhou, J.L., Ngo, H.H., Guo, W., Thomaidis, N.S. & Xu, J. 2017, 'Progress in the biological and chemical treatment technologies for emerging contaminant removal from wastewater: A critical review.', Journal of hazardous materials, vol. 323, pp. 274-298.
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This review focuses on the removal of emerging contaminants (ECs) by biological, chemical and hybrid technologies in effluents from wastewater treatment plants (WWTPs). Results showed that endocrine disruption chemicals (EDCs) were better removed by membrane bioreactor (MBR), activated sludge and aeration processes among different biological processes. Surfactants, EDCs and personal care products (PCPs) can be well removed by activated sludge process. Pesticides and pharmaceuticals showed good removal efficiencies by biological activated carbon. Microalgae treatment processes can remove almost all types of ECs to some extent. Other biological processes were found less effective in ECs removal from wastewater. Chemical oxidation processes such as ozonation/H2O2, UV photolysis/H2O2 and photo-Fenton processes can successfully remove up to 100% of pesticides, beta blockers and pharmaceuticals, while EDCs can be better removed by ozonation and UV photocatalysis. Fenton process was found less effective in the removal of any types of ECs. A hybrid system based on ozonation followed by biological activated carbon was found highly efficient in the removal of pesticides, beta blockers and pharmaceuticals. A hybrid ozonation-ultrasound system can remove up to 100% of many pharmaceuticals. Future research directions to enhance the removal of ECs have been elaborated.
Liu, Y., Zhang, Y., Zhao, Z., Ngo, H.H., Guo, W., Zhou, J., Peng, L. & Ni, B.-.J. 2017, 'A modeling approach to direct interspecies electron transfer process in anaerobic transformation of ethanol to methane.', Environmental Science and Pollution Research, vol. 24, no. 1, pp. 855-863.
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Recent studies have shown that direct interspecies electron transfer (DIET) plays an important part in contributing to methane production from anaerobic digestion. However, so far anaerobic digestion models that have been proposed only consider two pathways for methane production, namely, acetoclastic methanogenesis and hydrogenotrophic methanogenesis, via indirect interspecies hydrogen transfer, which lacks an effective way for incorporating DIET into this paradigm. In this work, a new mathematical model is specifically developed to describe DIET process in anaerobic digestion through introducing extracellular electron transfer as a new pathway for methane production, taking anaerobic transformation of ethanol to methane as an example. The developed model was able to successfully predict experimental data on methane dynamics under different experimental conditions, supporting the validity of the developed model. Modeling predictions clearly demonstrated that DIET plays an important role in contributing to overall methane production (up to 33 %) and conductive material (i.e., carbon cloth) addition would significantly promote DIET through increasing ethanol conversion rate and methane production rate. The model developed in this work will potentially enhance our current understanding on syntrophic metabolism via DIET.
Ye, Y., Ngo, H.H., Guo, W., Liu, Y., Li, J., Liu, Y., Zhang, X. & Jia, H. 2017, 'Insight into chemical phosphate recovery from municipal wastewater.', Sci Total Environ, vol. 576, pp. 159-171.
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Phosphate plays an irreplaceable role in the production of fertilizers. However, its finite availability may not be enough to satisfy increasing demands for the fertilizer production worldwide. In this scenario, phosphate recovery can effectively alleviate this problem. Municipal wastewater has received high priority to recover phosphate because its quantity is considerable. Therefore, phosphate recovery from municipal wastewater can bring many benefits such as relieving the burden of increasing production of fertilizers and reduction in occurrence of eutrophication caused by the excessive concentration of phosphate in the released effluent. The chemical processes are the most widely applied in phosphate recovery in municipal wastewater treatment because they are highly stable and efficient, and simple to operate. This paper compares chemical technologies for phosphate recovery from municipal wastewater. As phosphate in the influent is transferred to the liquid and sludge phases, a technical overview of chemical phosphate recovery in both phases is presented with reference to mechanism, efficiency and the main governing parameters. Moreover, an analysis on their applications at plant-scale is also presented. The properties of recovered phosphate and its impact on crops and plants are also assessed with a discussion on the economic feasibility of the technologies.
Narottam Saha, M. Safiur Rahman, Ahmed, M., ZHou, Ngo & Guo 2017, 'Industrial metal pollution in water and probabilistic assessment of human health risk', Journal of Environmental Management, vol. 185, pp. 70-78.
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Concentration of eight heavy metals in surface and groundwater around Dhaka Export Processing Zone (DEPZ) industrial area were investigated, and the health risk posed to local children and adult residents via ingestion and dermal contact was evaluated using deterministic and probabilistic approaches. Metal concentrations (except Cu, Mn, Ni, and Zn) in Bangshi River water were above the drinking water quality guidelines, while in groundwater were less than the recommended limits. Concentration of metals in surface water decreased as a function of distance. Estimations of non-carcinogenic health risk for surface water revealed that mean hazard index (HI) values of As, Cr, Cu, and Pb for combined pathways (i.e., ingestion and dermal contact) were >1.0 for both age groups. The estimated risk mainly came from the ingestion pathway. However, the HI values for all the examined metals in groundwater were <1.0, indicating no possible human health hazard. Deterministically estimated total cancer risk (TCR) via Bangshi River water exceeded the acceptable limit of 1 104 for adult and children. Although, probabilistically estimated 95th percentile values of TCR exceeded the benchmark, mean TCR values were less than 1 104 . Simulated results showed that 20.13% and 5.43% values of TCR for surface water were >1 104 for adult and children, respectively. Deterministic and probabilistic estimations of cancer risk through exposure to groundwater were well below the safety limit. Overall, the population exposed to Bangshi River water remained at carcinogenic and non-carcinogenic health threat and the risk was higher for adults. Sensitivity analysis identified exposure duration (ED) and ingestion rate (IR) of water as the most relevant variables affecting the probabilistic risk estimation model outcome. &copy;
Zhang, J., Sun, H., Wang, W., Hu, Z., Yin, X., Ngo, H.H., Guo, W. & Fan, J. 2017, 'Enhancement of surface flow constructed wetlands performance at low temperature through seasonal plant collocation.', Bioresour Technol, vol. 224, pp. 222-228.
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In the present study, a novel seasonal plant collocation system (SPCS), specifically the Potamogeton crispus and Phragmites australis series system, was investigated to enhance the performance of surface flow constructed wetlands (SFCWs) at low temperature. Results of a year-round experiment showed that SPCS conquered the adverse effect of low temperature and achieved sustainable nutrients removal. In addition, during winter, removal efficiencies of NH4-N, TP, COD, and TN in SPCS were 18.1%, 17.6%, 10.1% and 5.2% higher than that in the control, respectively. P. crispus and P. australis complemented each other in terms of plant growth and plant uptake during the experiment period. Furthermore, it emerged that P. crispus could increase the quantity of ammonia oxidizing bacteria by 10.2%, due to its high oxygen enrichment ability. It is suggested that seasonal plant collocation has a promising future in SFCWs of areas being affected by climate change, e.g. northern China.
Ahmed, M.B., Zhou, J.L., Ngo, H.H., Guo, W., Johir, M.A.H. & Sornalingam, K. 2017, 'Single and competitive sorption properties and mechanism of functionalized biochar for removing sulfonamide antibiotics from water', Chemical Engineering Journal, vol. 311, pp. 348-358.
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&copy; 2016 Elsevier B.V.Single and competitive sorption of ionisable sulphonamides sulfamethazine, sulfamethoxazole and sulfathiazole on functionalized biochar was highly pH dependent. The equilibrium data were well represented by both Langmuir and Freundlich models for single solutes, and by the Langmuir model for competitive solutes. Sorption capacity and distribution coefficient values decreased as sulfathiazole&nbsp;>&nbsp;sulfamethoxazole&nbsp;>&nbsp;sulfamethazine. The sorption capacity of each antibiotic in competitive mode is about three times lower than in single solute sorption. The kinetics data were best described by the pseudo second-order (PSO) model for single solutes, and by PSO and intra-particle diffusion models for competitive solutes. Adsorption mechanism was governed by pore filling through diffusion process. The findings from pH shift, FTIR spectra and Raman band shift showed that sorption of neutral sulfonamide species occurred mainly due to strong H-bonds followed by +- electron-donor-acceptor (EDA), and by Lewis acid-base interaction. Moreover, EDA was the main mechanism for the sorption of positive sulfonamides species. The sorption of negative species was mainly regulated by proton exchange with water forming negative charge assisted H-bond (CAHB), followed by the neutralization of &#8211;OH groups by H+ released from functionalized biochar surface; in addition - electron-acceptor-acceptor (EAA) interaction played an important role.
Kang, Y., Zhang, J., Xie, H., Guo, Z., Ngo, H.H., Guo, W. & Liang, S. 2017, 'Enhanced nutrient removal and mechanisms study in benthic fauna added surface-flow constructed wetlands: The role of Tubifex tubifex.', Bioresour Technol, vol. 224, pp. 157-165.
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This study designed a combined benthic fauna-T. orientalis-substrate-microbes surface-flow constructed wetlands (SFCWs) through the addition of T. tubifex. Results showed that, the removal efficiencies of nitrogen and phosphorus in the tested SFCWs achieved 81.14&plusmn;4.16% and 70.49&plusmn;7.60%, which were 22.27% and 27.35% higher than that without T. tubifex. Lower nitrate (2.11&plusmn;0.79mg/L) and ammonium (0.75&plusmn;0.64mg/L) were also observed in the tested SFCWs, which were 3.46mg/L and 0.52mg/L lower than that without T. tubifex. Microbial study confirmed the increased denitrifiers with T. tubifex. The lower nitrogen in effluent was also attributed to higher contents of nitrogen storage in sediment and T. orientalis due to the bioturbation of T. tubifex. Furthermore, with T. tubifex, higher proportions of particulate (22.66&plusmn;3.96%) and colloidal phosphorus (20.57&plusmn;3.39%) observed promoted phosphorus settlement and further absorption by T. orientalis. The outcomes of this study provides an ecological and economical strategy for improving the performance of SFCWs.
Nguyen, D.D., Yoon, Y.S., Nguyen, N.D., Bach, Q.V., Bui, X.T., Chang, S.W., Le, H.S., Guo, W. & Ngo, H.H. 2017, 'Enhanced efficiency for better wastewater sludge hydrolysis conversion through ultrasonic hydrolytic pretreatment', Journal of the Taiwan Institute of Chemical Engineers, vol. 71, pp. 244-252.
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&copy; 2016 Taiwan Institute of Chemical Engineers.The major requirements for accelerating the process of anaerobic digestion and energy production are breaking the structure of waste activated sludge (WAS), and transforming it into a soluble form suitable for biodegradation. This work investigated and analysed a novel bench-scale ultrasonic system for WAS disruption and hydrolysis using ultrasonic homogenization. Different commercial sonoreactors were used at low frequencies under a variety of operating conditions (intensity, density, power, sonication time, and total suspended solids) to evaluate the effects of the equipment on sludge hydrolysis and to generate new insights into the empirical models and mechanisms applicable to the real-world processing of wastewater sludge. A relationship was established between the operating parameters and the experimental data. Results indicated an increase in sonication time or ultrasonic intensity correlated with improved sludge hydrolysis rates, sludge temperature, and reduction rate of volatile solids (33.51%). It also emerged that ultrasonication could effectively accelerate WAS hydrolysis to achieve disintegration within 5-10 min, depending on the ultrasonic intensity. This study also determined multiple alternative parameters to increase the efficiency of sludge treatment and organic matter reduction, and establish the practicality of applying ultrasonics to wastewater sludge pretreatment.
Abdolali, A., Ngo, H.H., Guo, W., Zhou, J.L., Zhang, J., Liang, S., Chang, S.W., Nguyen, D.D. & Liu, Y. 2017, 'Application of a breakthrough biosorbent for removing heavy metals from synthetic and real wastewaters in a lab-scale continuous fixed-bed column.', Bioresour Technol, vol. 229, pp. 78-87.
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A continuous fixed-bed study was carried out utilising a breakthrough biosorbent, specifically multi-metal binding biosorbent (MMBB) for removing cadmium, copper, lead and zinc. The effect of operating conditions, i.e. influent flow rate, metal concentration and bed depth was investigated at pH 5.5&plusmn;0.1 for a synthetic wastewater sample. Results confirmed that the total amount of metal adsorption declined with increasing influent flow rate and also rose when each metal concentration also increased. The maximum biosorption capacities of 38.25, 63.37, 108.12 and 35.23mg/g for Cd, Cu, Pb and Zn, respectively, were achieved at 31cm bed height, 10mL/min flow rate and 20mg/L initial concentration. The Thomas model better described the whole dynamic behaviour of the column rather than the Dose Response and Yoon-Nelson models. Finally, desorption studies indicated that metal-loaded biosorbent could be used after three consecutive sorption, desorption and regeneration cycles by applying a semi-simulated real wastewater.
Nguyen, N.C., Chen, S.S., Nguyen, H.T., Chen, Y.H., Ngo, H.H., Guo, W., Ray, S.S., Chang, H.M. & Le, Q.H. 2017, 'Applicability of an integrated moving sponge biocarrier-osmotic membrane bioreactor MD system for saline wastewater treatment using highly salt-tolerant microorganisms', Separation and Purification Technology.
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&copy; 2017 Elsevier B.V.Osmotic membrane bioreactors (OsMBRs) are a recent breakthrough technology designed to treat wastewater. Nevertheless, their application in high-salinity wastewater treatment is not widespread because of the effects of saline conditions on microbial community activity. In response, this study developed an integrated sponge biocarrier-OsMBR system using highly salt-tolerant microorganisms for treating saline wastewater. Results showed that the sponge biocarrier-OsMBR obtained an average water flux of 2L/m2 h during a 92-day operation when 1M MgCl2 was used as the draw solution. The efficiency in removing dissolved organic compounds from the proposed system was more than 99%, and nutrient rejection was close to 100%, indicating excellent performance in simultaneous nitrification and denitrification processes in the biofilm layer on the carriers. Moreover, salt-tolerant microorganisms in the sponge biocarrier-OsMBR system worked efficiently in salt concentrations of 2.4%. A polytetrafluoroethylene MD membrane (pores=0.45m) served to regenerate the diluted draw solution in the closed-loop system and produce high-quality water. The moving sponge biocarrier-OsMBR/MD hybrid system demonstrated its potential to treat salinity wastewater treatment, with 100% nutrient removal and 99.9% conductivity rejection.
Wu, H., Zhang, J., Ngo, H.H., Guo, W. & Liang, S. 2017, 'Evaluating the sustainability of free water surface flow constructed wetlands: Methane and nitrous oxide emissions', Journal of Cleaner Production, vol. 147, pp. 152-156.
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Li, X., Mo, Y., Li, J., Guo, W. & Ngo, H.H. 2017, 'In-situ monitoring techniques for membrane fouling and local filtration characteristics in hollow fiber membrane processes: A critical review', Journal of Membrane Science, vol. 528, pp. 187-200.
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Wei, D., Zhang, K., Ngo, H.H., Guo, W., Wang, S., Li, J., Han, F., Du, B. & Wei, Q. 2017, 'Nitrogen removal via nitrite in a partial nitrification sequencing batch biofilm reactor treating high strength ammonia wastewater and its greenhouse gas emission.', Bioresour Technol, vol. 230, pp. 49-55.
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In present study, the feasibility of partial nitrification (PN) process achievement and its greenhouse gas emission were evaluated in a sequencing batch biofilm reactor (SBBR). After 90days' operation, the average effluent NH4(+)-N removal efficiency and nitrite accumulation rate of PN-SBBR were high of 98.2% and 87.6%, respectively. Both polysaccharide and protein contents were reduced in loosely bound extracellular polymeric substances (LB-EPS) and tightly bound EPS (TB-EPS) during the achievement of PN-biofilm. Excitation-emission matrix spectra implied that aromatic protein-like, tryptophan protein-like and humic acid-like substances were the main compositions of both kinds of EPS in seed sludge and PN-biofilm. According to typical cycle, the emission rate of CO2 had a much higher value than that of N2O, and their total amounts per cycle were 67.7 and 16.5mg, respectively. Free ammonia (FA) played a significant role on the inhibition activity of nitrite-oxidizing bacteria and the occurrence of nitrite accumulation.
Wu, Y., Yang, Q., Zeng, Q., Ngo, H.H., Guo, W. & Zhang, H. 2017, 'Enhanced low C/N nitrogen removal in an innovative microbial fuel cell (MFC) with electroconductivity aerated membrane (EAM) as biocathode', Chemical Engineering Journal, vol. 316, pp. 315-322.
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Li, M., Wu, H., Zhang, J., Ngo, H.H., Guo, W. & Kong, Q. 2017, 'Nitrogen removal and nitrous oxide emission in surface flow constructed wetlands for treating sewage treatment plant effluent: Effect of C/N ratios.', Bioresour Technol, vol. 240, pp. 157-164.
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In order to design treatment wetlands with maximal nitrogen removal and minimal nitrous oxide (N2O) emission, the effect of influent C/N ratios on nitrogen removal and N2O emission in surface flow constructed wetlands (SF CWs) for sewage treatment plant effluent treatment was investigated in this study. The results showed that nitrogen removal and N2O emission in CWs were significantly affected by C/N ratio of influent. Much higher removal efficiency of NH4(+)-N (98%) and TN (90%) was obtained simultaneously in SF CWs at C/N ratios of 12:1, and low N2O emission (8.2mg/m(2)/d) and the percentage of N2O-N emission in TN removal (1.44%) were also observed. These results obtained in this study would be utilized to determine how N2O fluxes respond to variations in C/N ratios and to improve the sustainability of CWs for wastewater treatment.
Liu, Y., Ngo, H.H., Guo, W., Sun, J., Wang, D., Peng, L. & Ni, B.-.J. 2017, 'Modeling aerobic biotransformation of vinyl chloride by vinyl chloride-assimilating bacteria, methanotrophs and ethenotrophs.', J Hazard Mater, vol. 332, pp. 97-103.
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Recent studies have investigated the potential of enhanced groundwater Vinyl Chloride (VC) remediation in the presence of methane and ethene through the interactions of VC-assimilating bacteria, methanotrophs and ethenotrophs. In this study, a mathematical model was developed to describe aerobic biotransformation of VC in the presence of methane and ethene for the first time. It examines the metabolism of VC by VC-assimilating bacteria as well as cometabolism of VC by both methanotrophs and ethenotrophs, using methane and ethene respectively, under aerobic conditions. The developed model was successfully calibrated and validated using experimental data from microcosms with different experimental conditions. The model satisfactorily describes VC, methane and ethene dynamics in all microcosms tested. Modeling results describe that methanotrophic cometabolism of ethene promotes ethenotrophic VC cometabolism, which significantly enhances aerobic VC degradation in the presence of methane and ethene. This model is expected to be a useful tool to support effective and efficient processes for groundwater VC remediation.
Nguyen, T.T., Bui, X.T., Luu, V.P., Nguyen, P.D., Guo, W. & Ngo, H.H. 2017, 'Removal of antibiotics in sponge membrane bioreactors treating hospital wastewater: Comparison between hollow fiber and flat sheet membrane systems', Bioresource Technology.
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&copy; 2017 Elsevier Ltd.Hollow fiber (HF) and flat sheet (FS) Sponge MBRs were operated at 10-20 LMH flux treating hospital wastewater. Simultaneous nitrification denitrification (SND) occurred considerably with TN removal rate of 0.011-0.020mg TN mgVSS-1 d-1. Furthermore, there was a remarkable removal of antibiotics in both Sponge MBRs, namely Norfloxacin (93-99% (FS); 62-86% (HF)), Ofloxacin (73-93% (FS); 68-93% (HF)), Ciprofloxacin (76-93% (FS); 54-70% (HF)), Tetracycline (approximately 100% for both FS and HF) and Trimethoprim (60-97% (FS); 47-93% (HF). Whereas there was a quite high removal efficiency of Erythromycin in Sponge MBRs, with 67-78% (FS) and 22-48% (HF). Moreover, a slightly higher removal of antibiotics in FS than in HF achieved, with the removal rate being of 0.67-32.40 and 0.44-30.42gmgVSS-1 d-1, respectively. In addition, a significant reduction of membrane fouling of 2-50 times was achieved in HF-Sponge MBR for the flux range.
Phan, T.N., Van Truong, T.T., Ha, N.B., Nguyen, P.D., Bui, X.T., Dang, B.T., Doan, V.T., Park, J., Guo, W. & Ngo, H.H. 2017, 'High rate nitrogen removal by ANAMMOX internal circulation reactor (IC) for old landfill leachate treatment', Bioresource Technology, vol. 234, pp. 281-288.
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Yang, S., Phan, H.V., Bustamante, H., Guo, W., Ngo, H.H. & Nghiem, L.D. 2017, 'Effects of shearing on biogas production and microbial community structure during anaerobic digestion with recuperative thickening.', Bioresour Technol, vol. 234, pp. 439-447.
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Recuperative thickening can intensify anaerobic digestion to produce more biogas and potentially reduce biosolids odour. This study elucidates the effects of sludge shearing during the thickening process on the microbial community structure and its effect on biogas production. Medium shearing resulted in approximately 15% increase in biogas production. By contrast, excessive or high shearing led to a marked decrease in biogas production, possibly due to sludge disintegration and cell lysis. Microbial analysis using 16S rRNA gene amplicon sequencing showed that medium shearing increased the evenness and diversity of the microbial community in the anaerobic digester, which is consistent with the observed improved biogas production. By contrast, microbial diversity decreased under either excessive shearing or high shearing condition. In good agreement with the observed decrease in biogas production, the abundance of Bacteroidales and Syntrophobaterales (which are responsible for hydrolysis and acetogenesis) decreased due to high shearing during recuperative thickening.
Zuthi, M.F.R., Guo, W., Ngo, H.H., Nghiem, D.L., Hai, F.I., Xia, S., Li, J., Li, J. & Liu, Y. 2017, 'New and practical mathematical model of membrane fouling in an aerobic submerged membrane bioreactor.', Bioresour Technol, vol. 238, pp. 86-94.
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This study aimed to develop a practical semi-empirical mathematical model of membrane fouling that accounts for cake formation on the membrane and its pore blocking as the major processes of membrane fouling. In the developed model, the concentration of mixed liquor suspended solid is used as a lumped parameter to describe the formation of cake layer including the biofilm. The new model considers the combined effect of aeration and backwash on the foulants' detachment from the membrane. New exponential coefficients are also included in the model to describe the exponential increase of transmembrane pressure that typically occurs after the initial stage of an MBR operation. The model was validated using experimental data obtained from a lab-scale aerobic sponge-submerged membrane bioreactor (MBR), and the simulation of the model agreed well with the experimental findings.
Nguyen, D.D., Yeop, J.S., Choi, J., Kim, S., Chang, S.W., Jeon, B.-.H., Guo, W. & Ngo, H.H. 2017, 'A new approach for concurrently improving performance of South Korean food waste valorization and renewable energy recovery via dry anaerobic digestion under mesophilic and thermophilic conditions.', Waste Management, vol. 66, pp. 161-168.
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Dry semicontinuous anaerobic digestion (AD) of South Korean food waste (FW) under four solid loading rates (SLRs) (2.30-9.21kg total solids (TS)/m(3)day) and at a fixed TS content was compared between two digesters, one each under mesophilic and thermophilic conditions. Biogas production and organic matter reduction in both digesters followed similar trends, increasing with rising SLR. Inhibitor (intermediate products of the anaerobic fermentation process) effects on the digesters' performance were not observed under the studied conditions. In all cases tested, the digesters' best performance was achieved at the SLR of 9.21kg TS/m(3)day, with 74.02% and 80.98% reduction of volatile solids (VS), 0.87 and 0.90m(3) biogas/kg VSremoved, and 0.65 (65% CH4) and 0.73 (60.02% CH4) m(3) biogas/kg VSfed, under mesophilic and thermophilic conditions, respectively. Thermophilic dry AD is recommended for FW treatment in South Korea because it is more efficient and has higher energy recovery potential when compared to mesophilic dry AD.
Ahmed, M., Guo, W., Zhou, J., Johir, M. & Ngo, H. 2017, 'Competitive sorption affinity of sulfonamides and chloramphenicol antibiotics toward functionalized biochar for water and wastewater treatment', Bioresource Technology.
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Competitive sorption of sulfamethazine (SMT), sulfamethoxazole (SMX), sulfathiazole (STZ) and chloramphenicol (CP) toward functionalized biochar (fBC) was highly pH dependent with maximum sorption at pH 4.0-4.25. Equilibrium data were well represented by the Langmuir and Freundlich models in the order STZ > SMX > CP > SMT. Kinetics data were slightly better fitted by the pseudo second-order model than pseudo first-order and intra-particle-diffusion models. Maximum sorptive interactions occurred at pH 4.0-4.25 through H-bonds formations for neutral sulfonamides species and through negative charge assisted H-bond (CAHB) formation for CP, in addition to - electron-donor-acceptor (EDA) interactions. EDA was the main mechanism for the sorption of positive sulfonamides species and CP at pH < 2.0. Sorption of negative sulfonamides species and CP at pH > 7.0 was regulated by H-bond formation and proton exchange with water by forming CAHB, respectively. The results suggested fBC to be highly efficient in removing antibiotics mixture.
Ahmed, M., zhou, J., Ngo, H., Guo, W., Johir, M. & Kiressan, S. 2017, 'Nano-Fe0 Immobilized onto Functionalized Biochar Gaining Excellent Stability during Sorption and Reduction of Chloramphenicol via Transforming to Reusable Magnetic Composite', Chemical Engineering Journal, vol. 322, pp. 571-581.
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The widely used nanosized zero-valent iron (nZVI or nFe0) particles and their composite material lose reductive nature during application, and the stability of transformed composite material for repeatable application is not addressed to date. To shed light on this, nZVI was synthesized from scrap material and immobilized on functionalized biochar (fBC) to prepare nZVI-fBC composite. Comparative study between nZVI and nZVI-fBC composite on the removal of chlorinated antibiotic chloramphenicol from different water types was conducted. The results suggested that nZVI was solely responsible for reduction of chloramphenicol. Whereas nZVI-fBC could be applied once, within a few hours, for the reduction of chloramphenico (29&#8211;32.5%) and subsequently sorption (67.5&#8211;70.5%) by transforming to a fully magnetic composite (nFe3O4-fBC) gaining stability with synergistic sorption performance. In both cases, two reduction by-products were identified namely 2-chloro-N-[1,3-dihydroxy-1-(4-aminophenyl)propan-2-yl]acetamide (m/z 257) and dechlorinated N-[1,3-dihydroxy-1-(4-aminophenyl)propan-2-yl]acetamide (m/z 223). The complete removal of 3.1 &micro;M L1 of chloramphenicol in different water was faster by nZVI-fBC (12&#8211;15 h) than by stable nFe3O4-fBC composite (18 h). Both nZVI-fBC and nFe3O4-fBC composites removed chloramphenicol in the order: deionized water > lake water > synthetic wastewater. nFe3O4-fBC showed excellent reusability after regeneration, with the regenerated nFe3O4-fBC composite (after 6 cycles of application) showing significant performance for methylene blue removal (287 mg g1). Therefore, the transformed nFe3O4-fBC composite is a promising and reusable sorbent for the efficient removal of organic contaminants.
Chen, C., Guo, W., Ngo, H.H., Chang, S.W., Duc Nguyen, D., Dan Nguyen, P., Bui, X.T. & Wu, Y. 2017, 'Impact of reactor configurations on the performance of a granular anaerobic membrane bioreactor for municipal wastewater treatment', International Biodeterioration and Biodegradation, vol. 121, pp. 131-138.
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Chen, C., Guo, W.S., Ngo, H.H., Liu, Y., Du, B., Wei, Q., Wei, D., Nguyen, D.D. & Chang, S.W. 2017, 'Evaluation of a sponge assisted-granular anaerobic membrane bioreactor (SG-AnMBR) for municipal wastewater treatment', Renewable Energy, vol. 111, pp. 620-627.
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Tran, V.S., Ngo, H.H., Guo, W., Ton-That, C., Li, J., Li, J. & Liu, Y. 2017, 'Removal of antibiotics (sulfamethazine, tetracycline and chloramphenicol) from aqueous solution by raw and nitrogen plasma modified steel shavings.', Sci Total Environ, vol. 601-602, pp. 845-856.
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The removal of sulfamethazine (SMT), tetracycline (TC) and chloramphenicol (CP) from synthetic wastewater by raw (M3) and nitrogen plasma modified steel shavings (M3-plN2) was investigated using batch experiments. The adsorption kinetics could be expressed by both pseudo-first-order kinetic (PFO) and pseudo-second-order kinetic (PSO) models, where correlation coefficient r(2) values were high. The values of PFO rate constant k1p and PSO rate constant k2p decreased as SMT-M3>SMT-M3-plN2>TC-M3-plN2>TC-M3>CP-M3>CP-M3-plN2 and SMT-M3>SMT-M3-plN2>TC-M3>TC-M3-plN2>CP-M3>CP-M3-plN2, respectively. Solution pH, adsorbent dose and temperature exerted great influences on the adsorption process. The plasma modification with nitrogen gas cleaned and enhanced 1.7-fold the surface area and 1.4-fold the pore volume of steel shavings. Consequently, the removal capacity of SMT, TC, CP on the adsorbent rose from 2519.98 to 2702.55, 1720.20 to 2158.36, and 2772.81 to 2920.11g/g, respectively. Typical chemical states of iron (XPS in Fe2p3 region) in the adsorbents which are mainly responsible for removing antibiotics through hydrogen bonding, electrostatic and non- electrostatic interactions and redox reaction were as follows: Fe3O4/Fe(2+), Fe3O4/Fe(3+), FeO/Fe(2+) and Fe2O3/Fe(3+).
Li, J., Jiang, B., Liu, Y., Qiu, C., Hu, J., Qian, G., Guo, W. & Ngo, H.H. 2017, 'Preparation and adsorption properties of magnetic chitosan composite adsorbent for Cu2+ removal', Journal of Cleaner Production, vol. 158, pp. 51-58.
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Ahmed, M.B., Johir, M.A.H., Zhou, J.L., Ngo, H.H., Guo, W. & Sornalingam, K. 2017, 'Photolytic and Photocatalytic Degradation of Organic UV Filters in Contaminated Water', Current Opinion in Green and Sustainable Chemistry.
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Wang, Q., Xie, H., Ngo, H.H., Guo, W., Zhang, J., Liu, C., Liang, S., Hu, Z., Yang, Z. & Zhao, C. 2016, 'Microbial abundance and community in subsurface flow constructed wetland microcosms: role of plant presence.', Environmental science and pollution research international, vol. 23, no. 5, pp. 4036-4045.
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In this research, the role of plants in improving microorganism growth conditions in subsurface flow constructed wetland (CW) microcosms was determined. In particular, microbial abundance and community were investigated during summer and winter in Phragmites australis-planted CW microcosms (PA) and unplanted CW microcosms (control, CT). Results revealed that the removal efficiencies of pollutants and microbial community structure varied in winter with variable microbial abundance. During summer, PA comprised more dominant phyla (e.g., Proteobacteria, Actinobacteria, and Bacteroidetes), whereas CT contained more Cyanobacteria and photosynthetic bacteria. During winter, the abundance of Proteobacteria was >40&nbsp;% in PA but dramatically decreased in CT. Moreover, Cyanobacteria and photosynthetic bacterial dominance in CT decreased. In both seasons, bacteria were more abundant in root surfaces than in sand. Plant presence positively affected microbial abundance and community. The potential removal ability of CT, in which Cyanobacteria and photosynthetic bacteria were abundant during summer, was more significantly affected by temperature reduction than that of PA with plant presence.
Abdolali, A., Ngo, H.H., Guo, W., Lu, S., Chen, S.-.S., Nguyen, N.C., Zhang, X., Wang, J. & Wu, Y. 2016, 'A breakthrough biosorbent in removing heavy metals: Equilibrium, kinetic, thermodynamic and mechanism analyses in a lab-scale study', SCIENCE OF THE TOTAL ENVIRONMENT, vol. 542, pp. 603-611.
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Luo, W., Phan, H.V., Hai, F.I., Price, W.E., Guo, W., Ngo, H.H., Yamamoto, K. & Nghiem, L.D. 2016, 'Effects of salinity build-up on the performance and bacterial community structure of a membrane bioreactor.', Bioresour Technol, vol. 200, pp. 305-310.
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This study investigated the effects of salinity increase on bacterial community structure in a membrane bioreactor (MBR) for wastewater treatment. The influent salt loading was increased gradually to simulate salinity build-up in the bioreactor during the operation of a high retention-membrane bioreactor (HR-MBR). Bacterial community diversity and structure were analyzed using 454 pyrosequencing of 16S rRNA genes of MBR mixed liquor samples. Results show that salinity increase reduced biological performance but did not affect microbial diversity in the bioreactor. Unweighted UniFrac and taxonomic analyses were conducted to relate the reduced biological performance to the change of bacterial community structure. In response to the elevated salinity condition, the succession of halophobic bacteria by halotolerant/halophilic microbes occurred and thereby the biological performance of MBR was recovered. These results suggest that salinity build-up during HR-MBR operation could be managed by allowing for the proliferation of halotolerant/halophilic bacteria.
Luo, W., Hai, F.I., Price, W.E., Guo, W., Ngo, H.H., Yamamoto, K. & Nghiem, L.D. 2016, 'Phosphorus and water recovery by a novel osmotic membrane bioreactor-reverse osmosis system.', Bioresour Technol, vol. 200, pp. 297-304.
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An osmotic membrane bioreactor-reverse osmosis (OMBR-RO) hybrid system integrated with periodic microfiltration (MF) extraction was evaluated for simultaneous phosphorus and clean water recovery from raw sewage. In this hybrid system, the forward osmosis membrane effectively retained inorganic salts and phosphate in the bioreactor, while the MF membrane periodically bled them out for phosphorus recovery with pH adjustment. The RO process was used for draw solute recovery and clean water production. Results show that phosphorus recuperation from the MF permeate was most effective when the solution pH was adjusted to 10, whereby the recovered precipitate contained 15-20% (wt/wt) of phosphorus. Periodic MF extraction also limited salinity build-up in the bioreactor, resulting in a stable biological performance and an increase in water flux during OMBR operation. Despite the build-up of organic matter and ammonia in the draw solution, OMBR-RO allowed for the recovery of high quality reused water.
Zhang, J., Jia, W., Wang, R., Ngo, H.H., Guo, W., Xie, H. & Liang, S. 2016, 'Microbial community characteristics during simultaneous nitrification-denitrification process: effect of COD/TP ratio.', Environmental science and pollution research international, vol. 23, no. 3, pp. 2557-2565.
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To evaluate the impact of chemical oxygen demand (COD)/total phosphorus (TP) ratio on microbial community characteristics during low-oxygen simultaneous nitrification and denitrification process, three anaerobic-aeration (low-oxygen) sequencing batch reactors, namely R1, R2, and R3, were performed under three different COD/TP ratios of 91.6, 40.8, and 27.6. The community structures of each reactor were analyzed via molecular biological technique. The results showed that the composition of ammonia-oxidizing bacteria (AOB) was affected, indicated by Shannon indexes of the samples from R1, R2, and R3. Nitrosomonas was identified to be the dominant AOB in all SBRs. Moreover, the copy numbers of nitrifiers were more than those of denitrifiers, and the phosphorus-accumulating organisms to glycogen-accumulating organisms ratio increased with the decrease of COD/TP ratio.
Ahmed, M.B., Zhou JL, Ngo HH & Guo W 2016, 'insights into biochar properties and its cost analysis', Biomass and Bioenergy, vol. 84, pp. 76-86.
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Biochars (BCs) are widely produced and used for the remediation of environmental contaminants as bio-sorbents. In this review, statistical analysis of different BC physico&#8211;chemical properties was conducted. It was observed that woody materials are the most suitable for preparing BCs, among many other potential raw materials such as food wastes and agricultural materials. Currently BCs are produced through a variety of thermal treatment processes between 300 and 900 &deg;C, among which slow pyrolysis is widely used due to its moderate operating conditions and optimization of BC yields. Hydrothermal carbonisation (HTC) is also an effective approach for BC production under certain conditions. As pyrolysis temperature is increased, the carbon content, ash content, surface area, and pore volume tend to be increased while the yield, hydrogen, oxygen, nitrogen content, and H/C and O/C molar ratios tend to decrease. The economic feasibility of BCs depends on a range of factors from raw material price to efficient production technologies. Thus, the overall cost equation of a pilot BC production plant together with the cost equation for BC regeneration has been proposed. The future research directions of BCs are also elaborated
Wang, J., Bi, F., Ngo, H.H., Guo, W., Jia, H., Zhang, H. & Zhang, X. 2016, 'Evaluation of energy-distribution of a hybrid microbial fuel cell-membrane bioreactor (MFC-MBR) for cost-effective wastewater treatment.', Bioresource technology, vol. 200, pp. 420-425.
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A low-cost hybrid system integrating a membrane-less microbial fuel cell (MFC) with an anoxic/oxic membrane bioreactor (MBR) was studied for fouling mitigation. The appended electric field in the MBR was supplied by the MFC with continuous flow. Supernatant from an anaerobic reactor with low dissolved oxygen was used as feed to the MFC in order to enhance its performance compared with that fed with synthetic wastewater. The voltage output of MFC maintained at 0.52&plusmn;0.02V with 1000 resister. The electric field intensity could reach to 0.114Vcm(-1). Compared with the conventional MBR (CMBR), the contents rather than the components of foulants on the cake layer of fouled MFC-MBR system was significantly reduced. Although only 0.5% of the feed COD was translated into electricity and applied to MBR, the hybrid system showed great feasibility without additional consumption but extracting energy from waste water and significantly enhancing the membrane filterability.
Johir, M.A.H., Nguyen, T.T., Mahatheva, K., Pradhan, M., Ngo, H.H., Guo, W. & Vigneswaran, S. 2016, 'Removal of phosphorus by a high rate membrane adsorption hybrid system', Bioresource Technology, vol. 201, pp. 365-369.
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&copy; 2015 Elsevier Ltd. Membrane adsorption hybrid system (MAHS) was evaluated for the removal of phosphate from a high rate membrane bioreactor (HR-MBR) effluent. The HR-MBR was operated at permeate flux of 30L/m2 h. The results indicated that the HR-MBR could eliminate 93.1&plusmn;1.5% of DOC while removing less than 53% phosphate (PO4-P). Due to low phosphate removal by HR-MBR, a post-treatment of strong base anion exchange resin (Dowex*21K-XLT), and zirconium (IV) hydroxide were used as adsorbent in MAHS for further removal of phosphate from HR-MBR effluent. It was found that the MAHS enabled to eliminate more than 85% of PO4-P from HR-MBR effluent. Hence, HR-MBR followed by MAHS lead to simultaneous removal of organics and phosphate in a reliable manner. The experiments were conducted only for a short period to investigate the efficiency of these resins/adsorbents on the removal of phosphorus and high rate MBR for organic removal.
Zhao, C., Xie, H., Xu, J., Zhang, J., Liang, S., Hao, J., Ngo, H.H., Guo, W., Xu, X., Wang, Q. & Wang, J. 2016, 'Removal mechanisms and plant species selection by bioaccumulative factors in surface flow constructed wetlands (CWs): In the case of triclosan.', The Science of the total environment, vol. 547, pp. 9-16.
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Plants can bioaccumulate triclosan and bond with microbes and sediments in constructed wetlands (CWs) as well. However, little is known regarding the species-specific removal mechanism of CWs components and the selection of suitable wetland plant species for triclosan disposal. In this work, the use of bioaccumulation factors (BAFs) and biota to sediment accumulation factors (BSAFs) for choosing the best triclosan removal plant species was studied in laboratory-scale CWs. By the end of the experiment, over 80% of triclosan was removed and a specie-effect distribution was revealed in CWs with emergent, submerged and floating plants. By mass balance calculation, negative correlation between triclosan concentration in plants and degradation process was observed. The significant correlations between Log BSAFs values and triclosan concentration in plants or degradation contribution made it possible and reasonable in wetland plants selection. Introductions on plant species were provided considering the target removal process or regulation method. This work provided new information on plant species selection in CWs for triclosan removal or its emergency remediation by using bioaccumulative factors.
Nguyen, N.C., Chen, S.S., Nguyen, H.T., Ray, S.S., Ngo, H.H., Guo, W. & Lin, P.H. 2016, 'Innovative sponge-based moving bed–osmotic membrane bioreactor hybrid system using a new class of draw solution for municipal wastewater treatment.', Water research, vol. 91, pp. 305-313.
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For the first time, an innovative concept of combining sponge-based moving bed (SMB) and an osmotic membrane bioreactor (OsMBR), known as the SMB-OsMBR hybrid system, were investigated using Triton X-114 surfactant coupled with MgCl2 salt as the draw solution. Compared to traditional activated sludge OsMBR, the SMB-OsMBR system was able to remove more nutrients due to the thick-biofilm layer on sponge carriers. Subsequently less membrane fouling was observed during the wastewater treatment process. A water flux of 11.38&nbsp;L/(m(2)&nbsp;h) and a negligible reverse salt flux were documented when deionized water served as the feed solution and a mixture of 1.5&nbsp;M MgCl2 and 1.5&nbsp;mM Triton X-114 was used as the draw solution. The SMB-OsMBR hybrid system indicated that a stable water flux of 10.5&nbsp;L/(m(2)&nbsp;h) and low salt accumulation were achieved in a 90-day operation. Moreover, the nutrient removal efficiency of the proposed system was close to 100%, confirming the effectiveness of simultaneous nitrification and denitrification in the biofilm layer on sponge carriers. The overall performance of the SMB-OsMBR hybrid system using MgCl2 coupled with Triton X-114 as the draw solution demonstrates its potential application in wastewater treatment.
Wu, H., Fan, J., Zhang, J., Ngo, H.H., Guo, W., Liang, S., Lv, J., Lu, S., Wu, W. & Wu, S. 2016, 'Intensified organics and nitrogen removal in the intermittent-aerated constructed wetland using a novel sludge-ceramsite as substrate.', Bioresource technology, vol. 210, pp. 101-107.
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In this study, a novel sludge-ceramsite was applied as main substrate in intermittent-aerated subsurface flow constructed wetlands (SSF CWs) for treating decentralized domestic wastewater, and intensified organics and nitrogen removal in different SSF CWs (with and without intermittent aeration, with and without sludge-ceramsite substrate) were evaluated. High removal of 97.2% COD, 98.9% NH4(+)-N and 85.8% TN were obtained simultaneously in the intermittent-aerated CW system using sludge-ceramsite substrate compared with non-aerated CWs. Moreover, results from fluorescence in situ hybridization (FISH) analysis revealed that the growth of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in the intermittent-aerated CW system with sludge-ceramsite substrate was enhanced, thus indicating that the application of intermittent aeration and sludge-ceramsite plays an important role in nitrogen transformations. These results suggest that a combination of intermittent aeration and sludge-ceramsite substrate is reliable to enhance the treatment performance in SSF CWs.
Zheng, Y., Wang, X., Dzakpasu, M., Zhao, Y., Ngo, H.H., Guo, W., Ge, Y. & Xiong, J. 2016, 'Effects of interspecific competition on the growth of macrophytes and nutrient removal in constructed wetlands: A comparative assessment of free water surface and horizontal subsurface flow systems.', Bioresource technology, vol. 207, pp. 134-141.
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The outcome of competition between adjoining interspecific colonies of Phragmites and Typha in two large field pilot-scale free water surface (FWS) and subsurface flow (SSF) CWs is evaluated. According to findings, the effect of interspecific competition was notable for Phragmites australis, whereby it showed the highest growth performance in both FWS and SSF wetland. In a mixed-culture, P. australis demonstrates superiority in terms of competitive interactions for space between plants. Furthermore, the interspecific competition among planted species seemed to cause different ecological responses of plant species in the two CWs. For example, while relatively high density and shoot height determined the high aboveground dry weight of P. australis in the FWS wetland, this association was not evident in the SSF. Additionally, while plants nutrients uptake accounts for a higher proportion of the nitrogen removal in FWS, that in the SSF accounts for a higher proportion of the phosphorous removal.
Deng, L., Guo, W., Ngo, H.H., Du, B., Wei, Q., Tran, N.H., Nguyen, N.C., Chen, S.S. & Li, J. 2016, 'Effects of hydraulic retention time and bioflocculant addition on membrane fouling in a sponge-submerged membrane bioreactor.', Bioresource technology, vol. 210, pp. 11-17.
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The characteristics of activated sludge and membrane fouling were evaluated in a sponge-submerged membrane bioreactor (SSMBR) at different hydraulic retention times (HRTs) (6.67, 5.33 and 4.00h). At shorter HRT, more obvious membrane fouling was caused by exacerbated cake layer formation and aggravated pore blocking. Activated sludge possessed more extracellular polymeric substances (EPS) due to excessive growth of biomass and lower protein to polysaccharide ratio in soluble microbial products (SMP). The cake layer resistance was aggravated by increased sludge viscosity together with the accumulated EPS and biopolymer clusters (BPC) on membrane surface. However, SMP showed marginal effect on membrane fouling when SSMBRs were operated at all HRTs. The SSMBR with Gemfloc&reg; addition at the optimum HRT of 6.67h demonstrated superior sludge characteristics such as larger floc size, less SMP in mixed liquor with higher protein/polysaccharide ratio, less SMP and BPC in cake layer, thereby further preventing membrane fouling.
Nguyen, T.T., Bui, X.T., Pham, M.D., Guo, W. & Ngo, H.H. 2016, 'Effect of Tris-(hydroxymethyl)-amino methane on microalgae biomass growth in a photobioreactor.', Bioresour Technol, vol. 208, pp. 1-6.
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One of the buffers namely Tris (Tris-(hydroxymethyl)-amino methane) was used to increase the growth of microalgae by stabilizing the pH value in microalgae cultures. The objective of this research is to determine the growth rate and biomass productivity of Chlorella sp. with and without Tris addition. Both conditions function at various N:P ratios cultured in photobioreactors (carbon dioxide of 5%(v/v), light intensity of 3.3 Klux). Daily variations in nutrient removal (nitrogen and phosphorus), cell concentration, DO, temperature and pH were measured for data analysis. The results show that the largest yield of biomass was achieved at the N:P ratio of 15:1 with and without Tris. After cultivation lasting 92 h, the algae concentration at this ratio was 1250 mg L(-1) and 3568 mg L(-1) with and without Tris, respectively. This indicates that adding Tris to the photobioreactor greatly reduces algae biomass due to bacterial competition.
Nguyen, N.C., Nguyen, H.T., Chen, S.-.S., Ngo, H.H., Guo, W., Chan, W.H., Ray, S.S., Li, C.-.W. & Hsu, H.-.T. 2016, 'A novel osmosis membrane bioreactor-membrane distillation hybrid system for wastewater treatment and reuse.', Bioresource technology, vol. 209, pp. 8-15.
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A novel approach was designed to simultaneously enhance nutrient removal and reduce membrane fouling for wastewater treatment using an attached growth biofilm (AGB) integrated with an osmosis membrane bioreactor (OsMBR) system for the first time. In this study, a highly charged organic compound (HEDTA(3-)) was employed as a novel draw solution in the AGB-OsMBR system to obtain a low reverse salt flux, maintain a healthy environment for the microorganisms. The AGB-OsMBR system achieved a stable water flux of 3.62L/m(2)h, high nutrient removal of 99% and less fouling during a 60-day operation. Furthermore, the high salinity of diluted draw solution could be effectively recovered by membrane distillation (MD) process with salt rejection of 99.7%. The diluted draw solution was re-concentrated to its initial status (56.1mS/cm) at recovery of 9.8% after 6h. The work demonstrated that novel multi-barrier systems could produce high quality potable water from impaired streams.
Zhang, X., Guo, W., Ngo, H.H., Wen, H., Li, N. & Wu, W. 2016, 'Performance evaluation of powdered activated carbon for removing 28 types of antibiotics from water.', Journal of environmental management, vol. 172, pp. 193-200.
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Currently, the occurrence and fate of antibiotics in the aquatic environment has become a very serious problem in that they can potentially and irreversibly damage the ecosystem and human health. For this reason, interest has increased in developing strategies to remove antibiotics from water. This study evaluated the performance of powdered activated carbon (PAC) in removing from water 6 representative groups of 28 antibiotics, namely Tetracyclines (TCs), Macrolides (MCs), Chloramphenicols (CPs), Penicillins (PNs), Sulfonamides (SAs) and Quinolones (QNs). Results indicate that PAC demonstrated superior adsorption capacity for all selected antibiotics. The removal efficiency was up to 99.9% in deionized water and 99.6% in surface water at the optimum conditions with PAC dosage of 20&nbsp;mg/L and contact time of 120&nbsp;min. According to the Freundlich model's adsorption isotherm, the values of n varied among these antibiotics and most were less than 1, suggesting that the adsorption of antibiotics onto PAC was nonlinear. Adsorption of antibiotics followed well the pseudo-second-order kinetic model (R(2)&nbsp;=&nbsp;0.99). Analysis using the Weber-Morris model revealed that the intra-particle diffusion was not the only rate-controlling step. Overall, the findings in this study confirm that PAC is a feasible and viable option for removing antibiotics from water in terms of water quality improvement and urgent antibiotics pollution control. Further research is essential on the following subjects: (i) removing more types of antibiotics by PAC; (ii) the adsorption process; and (iii) the mechanism of the competitive adsorption existing between natural organic matters (NOMs) and antibiotics.
Deng, L., Guo, W., Ngo, H.H., Zhang, X., Wang, X.C., Zhang, Q. & Chen, R. 2016, 'New functional biocarriers for enhancing the performance of a hybrid moving bed biofilm reactor-membrane bioreactor system.', Bioresource technology, vol. 208, pp. 87-93.
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In this study, new sponge modified plastic carriers for moving bed biofilm reactor (MBBR) was developed. The performance and membrane fouling behavior of a hybrid MBBR-membrane bioreactor (MBBR-MBR) system were also evaluated. Comparing to the MBBR with plastic carriers (MBBR), the MBBR with sponge modified biocarriers (S-MBBR) showed better effluent quality and enhanced nutrient removal at HRTs of 12h and 6h. Regarding fouling issue of the hybrid systems, soluble microbial products (SMP) of the MBR unit greatly influenced membrane fouling. The sponge modified biocarriers could lower the levels of SMP in mixed liquor and extracellular polymeric substances in activated sludge, thereby mitigating cake layer and pore blocking resistances of the membrane. The reduced SMP and biopolymer clusters in membrane cake layer were also observed. The results demonstrated that the sponge modified biocarriers were capable of improving overall MBBR performance and substantially alleviated membrane fouling of the subsequent MBR unit.
Nguyen, N.C., Nguyen, H.T., Ho, S.-.T., Chen, S.-.S., Ngo, H.H., Guo, W., Ray, S.S. & Hsu, H.-.T. 2016, 'Exploring high charge of phosphate as new draw solute in a forward osmosis-membrane distillation hybrid system for concentrating high-nutrient sludge.', The Science of the total environment, vol. 557-558, pp. 44-50.
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For the first time, a high charge of phosphate was used as the draw solute in a forward osmosis-membrane distillation (FO-MD) hybrid system for concentrating high-nutrient sludge. A high water flux (12.5L/m(2)h) and a low reverse salt flux (0.84g/m(2)) were simultaneously achieved at pH9 by using 0.1M Na3PO4 as the draw solute and deionized water as the feed solution in the FO process. The specific reverse salt flux of 0.1M Na3PO4 (Js/Jw=0.07g/L) was considerably less than that of 0.1M NaCl (Js/Jw=0.37g/L) because the complexion between Na(+) and HPO4(2-) at pH9 led to the reduction of free Na(+) ions, which subsequently reduced the reverse salt diffusion substantially. Moreover, for a feed solution with an initial sludge concentration of 3500mg/L, the sludge concentration could be concentrated to 19,800 and 22,000mg/L in the pressure-retarded osmosis (PRO) and FO membrane orientations, respectively, after 15h of operation. Four types of MD membranes were selected for draw solution recovery; of these, a polytetrafluoroethylene membrane with a pore size of 0.45m was the most effective in achieving a high water flux (10.28L/m(2)h) and high salt rejection (approximately 100%) in a diluted Na3PO4 draw solution.
Nguyen, T.T., Bui, X.T., Vo, T.D.H., Nguyen, D.D., Nguyen, P.D., Do, H.L.C., Ngo, H.H. & Guo, W. 2016, 'Performance and membrane fouling of two types of laboratory-scale submerged membrane bioreactors for hospital wastewater treatment at low flux condition', Separation and Purification Technology, vol. 165, pp. 123-129.
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Chen, C., Guo, W., Ngo, H.H., Lee, D.J., Tung, K.L., Jin, P., Wang, J. & Wu, Y. 2016, 'Challenges in biogas production from anaerobic membrane bioreactors', Renewable Energy, vol. 98, pp. 120-134.
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&copy; 2016. Spectacular applications of anaerobic membrane bioreactors (AnMBRs) are emerging due to the membrane enhanced biogas production in the form of renewable bioresources. They produce similar energy derived from the world's depleting natural fossil energy sources while minimizing greenhouse gas (GHG) emissions. During the last decade, many types of AnMBRs have been developed and applied so as to make biogas technology practical and economically viable. Referring to both conventional and advanced configurations, this review presents a comprehensive summary of AnMBRs for biogas production in recent years. The potential of biogas production from AnMBRs cannot be fully exploited, since certain constraints still remain and these cause low methane yield. This paper addresses a detailed assessment on the potential challenges that AnMBRs are encountering, with a major focus on many inhibitory substances and operational dilemmas. The aim is to provide a solid platform for advances in novel AnMBRs applications for optimized biogas production.
Yin, X., Zhang, J., Hu, Z., Xie, H., Guo, W., Wang, Q., Ngo, H.H., Liang, S., Lu, S. & Wu, W. 2016, 'Effect of photosynthetically elevated pH on performance of surface flow-constructed wetland planted with Phragmites australis.', Environmental science and pollution research international, vol. 23, no. 15, pp. 15524-15531.
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Combination of emergent and submerged plants has been proved to be able to enhance pollutant removal efficiency of surface flow-constructed wetland (SFCW) during winter. However, intensive photosynthesis of submerged plants during summer would cause pH increase, which may have adverse effects on emergent plants. In this study, nitrogen transformation of lab-scale SFCW under pH gradient of 7.5, 8.5, 9.5 and 10.5 was systematically investigated. The results showed that total nitrogen (TN) removal efficiency decreased from 76.3&plusmn;0.04 to 51.8&plusmn;0.04&nbsp;% when pH increased from 7.5 to 10.5, which was mainly attributed to plant assimilation decay and inhibition of microbe activities (i.e., nitrite-oxidizing bacteria and denitrifiers). Besides, the highest sediment adsorption in SFCW was observed at pH of 8.5. In general, the combination of submerged and emergent plants is feasible for most of the year, but precaution should be taken to mitigate the negative effect of high alkaline conditions when pH rises to above 8.5 in midsummer.
Wu, H., Fan, J., Zhang, J., Ngo, H.H., Guo, W., Hu, Z. & Lv, J. 2016, 'Optimization of organics and nitrogen removal in intermittently aerated vertical flow constructed wetlands: Effects of aeration time and aeration rate', International Biodeterioration and Biodegradation, vol. 113, pp. 139-145.
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In this study, to optimize aeration for the enhancement of organics and nitrogen removal in intermittently aerated vertical flow constructed wetlands (VF CWs) for treating domestic wastewater, the experimental VF CWs were operated at different aeration time (1 h d-1, 2 h d-1, 4 h d-1, 6 h d-1, 8 h d-1 and 10 h d-1) and aeration rate (0.1 L min-1, 0.2 L min-1, 0.5 L min-1, 1.0 L min-1 and 2.0 L min-1) to investigate the effect of artificial aeration on the removal efficiency of organics and nitrogen. The results showed that the optimal aeration time and aeration rate were 4 h d-1 and 1.0 L min-1, which could create the appropriate aerobic and anoxic regions in CWs with the greater removal of COD (97.2%), NH4 +-N (98.4%) and TN (90.6%) achieved simultaneously during the experiment. The results demonstrate that the optimized intermittent aeration is reliable option to enhance the treatment performance of organics and nitrogen at a lower operating cost.
Wei, D., Dong, H., Wu, N., Ngo, H.H., Guo, W., Du, B. & Wei, Q. 2016, 'A Fluorescence Approach to Assess the Production of Soluble Microbial Products from Aerobic Granular Sludge Under the Stress of 2,4-Dichlorophenol.', Sci Rep, vol. 6, p. 24444.
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In this study, a fluorescence approach was used to evaluate the production of soluble microbial products (SMP) in aerobic granular sludge system under the stress of 2,4-dichlorophenol (2,4-DCP). A combined use of three-dimension excitation emission matrix fluorescence spectroscopy (3D-EEM), Parallel factor analysis (PARAFAC), synchronous fluorescence and two-dimensional correlation spectroscopy (2D-COS) were explored to respect the SMP formation in the exposure of different doses of 2,4-DCP. Data implied that the presence of 2,4-DCP had an obvious inhibition on biological nitrogen removal. According to EEM-PARAFAC, two fluorescent components were derived and represented to the presence of fulvic-like substances and humic-like substances in Component 1 and protein-like substances in Component 2. It was found from synchronous fluorescence that protein-like peak presented slightly higher intensity than that of fulvic-like peak. 2D-COS further revealed that fluorescence change took place sequentially in the following order: protein-like fraction > fulvic-like fraction. The obtained results could provide a potential application of fluorescence spectra in the released SMP assessment in the exposure of toxic compound during wastewater treatment.
Wei, D., Ngo, H.H., Guo, W., Xu, W., Zhang, Y., Du, B. & Wei, Q. 2016, 'Biosorption of effluent organic matter onto magnetic biochar composite: Behavior of fluorescent components and their binding properties.', Bioresour Technol, vol. 214, pp. 259-265.
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Effluent organic matter (EfOM) is of great concern as one of main sources of organic pollutants from biologically treated wastewater, which is harmful to the quality of receiving waters. In present study, magnetic biochar composite (MBC) was successfully prepared, characterizated and applied to EfOM treatment. The interaction between EfOM and MBC was explored by a combination of excitation-emission matrix (EEM), parallel factor analysis (PARAFAC), synchronous fluorescence, two-dimensional correlation spectroscopy (2D-COS), and molecular weight distribution. Result implied that two fluorescence components were derived from EEM-PARAFAC, and their relative fluorescence intensity scores expressed decreased trend. Moreover, fluorescence quenching of EfOM with increased MBC took place sequentially in the following order: protein-like fraction<fulvic-like and humic-like fractions. Molecular weight distribution suggested that MBC had different uptake ability to various size ranges of EfOM. The obtained results could provide a potential application of fluorescence spectroscopy for EfOM treatment assessment.
Bui, X.T., Vo, T.P.T., Ngo, H.H., Guo, W.S. & Nguyen, T.T. 2016, 'Multicriteria assessment of advanced treatment technologies for micropollutants removal at large-scale applications', Science of the Total Environment, vol. 563-564, pp. 1050-1067.
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&copy; 2016 Elsevier B.V. With the introduction and discharge of thousands of new micropollutants (MPs) every year, traditional water and wastewater treatment plants may be incapable of tackling them all. With their low concentrations and diversity in nature, MP removal encounters numerous challenges. Although some MPs are effectively eliminated via conventional treatment methods, most of them can easily escape and are retained in the discharged effluent. Therefore, advanced methods such as (i) adsorption, (ii) oxidation and advanced oxidation processes (O3 and O3-based advanced oxidation processes, UV/H2O2), (iii) membrane processes, and (iv) membrane bioreactors, become an inevitable approach. Despite the unsurprisingly vast number of papers on MP treatment available at present, most of these studies were carried out at a laboratory scale while only a few pilot- and full-scale studies have experimented. Nevertheless, an in-depth assessment of real-world MP treatment methods is extremely crucial for practitioners. To date, no paper has been dedicated to look at this issue. Therefore, this paper aims to review these large-scale treatment methods. First, the paper goes through the regulations and standards which deal with MPs in water courses. It will then assess these methods in various case-studies with reference to different criteria towards serving as a reference for further practical applications.
Fan, J., Zhang, J., Guo, W., Liang, S. & Wu, H. 2016, 'Enhanced long-term organics and nitrogen removal and associated microbial community in intermittently aerated subsurface flow constructed wetlands.', Bioresource technology, vol. 214, pp. 871-875.
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The long-term enhanced removal efficiency of organics and nitrogen in subsurface flow constructed wetlands (SSF CWs) with and without intermittent aeration for decentralized domestic wastewater was evaluated, and the function of intermittent aeration on microbial community was also investigated in this study. The high and long-term 95.6% COD, 96.1% NH4(+)-N and 85.8% TN removal efficiencies were achieved in experimental intermittently aerated SSF CW compared with non-aerated SSF CW. Aerated SSF CWs also exhibited the excellent removal performance when comparatively comparing with other strategies and techniques applied in CWs. In addition, fluorescence in situ hybridization (FISH) analysis revealed that associated microbial abundance significantly increased owing to intermittent aeration. These results indicated intermittent aeration CWs might be an effective and sustainable strategy for wastewater treatment in rural areas, but require further full-scale investigation in future.
Ahmed, M.B., Zhou, J.L., Ngo, H.H., Guo, W. & Chen, M. 2016, 'Progress in the preparation and application of modified biochar for improved contaminant removal from water and wastewater', BIORESOURCE TECHNOLOGY, vol. 214, pp. 836-851.
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Khan, M.A., Ngo, H.H., Guo, W.S., Liu, Y.W., Zhou, J.L., Zhang, J., Liang, S., Ni, B.J., Zhang, X.B. & Wang, J. 2016, 'Comparing the value of bioproducts from different stages of anaerobic membrane bioreactors', Bioresource Technology, vol. 214, pp. 816-825.
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Abstract The anaerobic digestion process in anaerobic membrane bioreactors is an effective way for waste management, energy sustainability and pollution control in the environment. This digestion process basically involves the production of volatile fatty acids and biohydrogen as intermediate products and methane as a final product. This paper compares the value of bioproducts from different stages of anaerobic membrane bioreactors through a thorough assessment. The value was assessed in terms of technical feasibility, economic assessment, environmental impact and impact on society. Even though the current research objective is more inclined to optimize the production of methane, the intermediate products could also be considered as economically attractive and environment friendly options. Hence, this is the first review study to correlate the idea into an anaerobic membrane bioreactor which is expected to guide future research pathways regarding anaerobic process and its bioproducts.
Liu, H., Hu, Z., Zhang, J., Ngo, H.H., Guo, W., Liang, S., Fan, J., Lu, S. & Wu, H. 2016, 'Optimizations on supply and distribution of dissolved oxygen in constructed wetlands: A review.', Bioresource technology, vol. 214, pp. 797-805.
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Dissolved oxygen (DO) is one of the most important factors that can influence pollutants removal in constructed wetlands (CWs). However, problems of insufficient oxygen supply and inappropriate oxygen distribution commonly exist in traditional CWs. Detailed analyses of DO supply and distribution characteristics in different types of CWs were introduced. It can be concluded that atmospheric reaeration (AR) served as the promising point on oxygen intensification. The paper summarized possible optimizations of DO in CWs to improve its decontamination performance. Process (tidal flow, drop aeration, artificial aeration, hybrid systems) and parameter (plant, substrate and operating) optimizations are particularly discussed in detail. Since economic and technical defects are still being cited in current studies, future prospects of oxygen research in CWs terminate this review.
Lu, S., Chen, F., Ngo, H.H., Guo, W., Feng, C., Wu, J. & Zheng, B. 2016, 'Effect of straw and polyacrylamide on the stability of land/water ecotone soil and the field implementation', Ecological Engineering, vol. 94, pp. 12-21.
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Song, X., McDonald, J., Price, W.E., Khan, S.J., Hai, F.I., Ngo, H.H., Guo, W. & Nghiem, L.D. 2016, 'Effects of salinity build-up on the performance of an anaerobic membrane bioreactor regarding basic water quality parameters and removal of trace organic contaminants.', Bioresour Technol, vol. 216, pp. 399-405.
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The effects of elevated inorganic salt concentration on anaerobic membrane bioreactor (AnMBR) treatment regarding basic biological performance and trace organic contaminant (TrOC) removal were investigated. A set of 33 TrOCs were selected to represent pharmaceuticals, steroids, and pesticides in municipal wastewater. Results show potential adverse effects of increase in the bioreactor salinity to 15g/L (as NaCl) on the performance of AnMBR with respect to chemical oxygen demand removal, biogas production, and the removal of most hydrophilic TrOCs. Furthermore, a decrease in biomass production was observed as salinity in the bioreactor increased. The removal of most hydrophobic TrOCs was high and was not significantly affected by salinity build-up in the bioreactor. The accumulation of a few persistent TrOCs in the sludge phase was observed, but such accumulation did not vary significantly as salinity in the bioreactor increased.
Zhang, Q.H., Jin, P.K., Ngo, H.H., Shi, X., Guo, W.S., Yang, S.J., Wang, X.C., Wang, X., Dzakpasu, M., Yang, W.N. & Yang, L. 2016, 'Transformation and utilization of slowly biodegradable organic matters in biological sewage treatment of anaerobic anoxic oxic systems.', Bioresource technology, vol. 218, pp. 53-61.
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This study examined the distribution of carbon sources in two anaerobic anoxic oxic (AAO) sewage treatment plants in Xi'an and investigated the transformation characteristics and utilization potential of slowly biodegradable organic matters (SBOM). Results indicated under anaerobic and aerobic conditions, SBOM could be transformed at a rate of 65% in 8h into more readily biologically utilizable substrates such as volatile fatty acids (VFAs), polysaccharides and proteins. Additionally, non-biodegradable humus-type substances which are difficult to biodegrade and readily accumulate, were also generated. These products could be further hydrolyzed to aldehyde and ketone compounds and then transformed into substances with significant oxygen-containing functional groups and utilized subsequently. The molecular weights of proteinoid substances had a wide distribution and tended to decrease over time. Long hours of microbial reaction increased the proportion of micromolecular substances. This particular increase generated significant bioavailability, which can greatly improve the efficiency of nitrogen removal.
Jia, H., Yang, G., Wang, J., Ngo, H.H., Guo, W., Zhang, H. & Zhang, X. 2016, 'Performance of a microbial fuel cell-based biosensor for online monitoring in an integrated system combining microbial fuel cell and upflow anaerobic sludge bed reactor.', Bioresource technology, vol. 218, pp. 286-293.
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A hybrid system integrating a microbial fuel cell (MFC)-based biosensor with upflow anaerobic sludge blanket (UASB) was investigated for real-time online monitoring of the internal operation of the UASB reactor. The features concerned were its rapidity and steadiness with a constant operation condition. In addition, the signal feedback mechanism was examined by the relationship between voltage and time point of changed COD concentration. The sensitivity of different concentrations was explored by comparing the signal feedback time point between the voltage and pH. Results showed that the electrical signal feedback was more sensitive than pH and the thresholds of sensitivity were S=310(-5)V/(mg/L) and S=810(-5)V/(mg/L) in different concentration ranges, respectively. Although only 0.94% of the influent COD was translated into electricity and applied for biosensing, this integrated system indicated great potential without additional COD consumption for real-time monitoring.
Liu, Y., Ngo, H.H., Guo, W., Peng, L., Pan, Y., Guo, J., Chen, X. & Ni, B.J. 2016, 'Autotrophic nitrogen removal in membrane-aerated biofilms: Archaeal ammonia oxidation versus bacterial ammonia oxidation', Chemical Engineering Journal, vol. 302, pp. 535-544.
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Ye, Y., Ngo, H.H., Guo, W., Liu, Y., Zhang, X., Guo, J., Ni, B.-.J., Chang, S.W. & Nguyen, D.D. 2016, 'Insight into biological phosphate recovery from sewage.', Bioresource technology, vol. 218, pp. 874-881.
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The world's increasing population means that more food production is required. A more sustainable supply of fertilizers mainly consisting of phosphate is needed. Due to the rising consumption of scarce resources and limited natural supply of phosphate, the recovery of phosphate and their re-use has potentially high market value. Sewage has high potential to recover a large amount of phosphate in a circular economy approach. This paper focuses on utilization of biological process integrated with various subsequent processes to concentrate and recycle phosphate which are derived from liquid and sludge phases. The phosphate accumulation and recovery are discussed in terms of mechanism and governing parameters, recovery efficiency, application at plant-scale and economy.
Fan, J., Zhang, J., Ngo, H.H., Guo, W. & Yin, X. 2016, 'Improving low-temperature performance of surface flow constructed wetlands using Potamogeton crispus L. plant.', Bioresource technology, vol. 218, pp. 1257-1260.
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In this study, enhanced organics and nitrogen removal efficiency in SFCWs by different submerged plants for polluted river water treatment under cold temperature was evaluated. High average removal efficiencies of COD (92.45%), NH4(+)-N (93.70%) and TN (55.62%) were achieved in experimental SFCWs with Potamogeton crispus compared with SFCWs with other plants. SFCWs with underground Phragmites australis root also presented better performance than the unplanted systems, indicating its positive role of contamination removal in winter. The results of this study indicated SFCWs with hardy submerged plant P. crispus could be a more effective and sustainable strategy for removing organics and nitrogen in shallow nutrient enriched river water ecosystems under cold climate.
Ansari, A.J., Hai, F.I., Guo, W., Ngo, H.H., Price, W.E. & Nghiem, L.D. 2016, 'Factors governing the pre-concentration of wastewater using forward osmosis for subsequent resource recovery.', Sci Total Environ, vol. 566-567, pp. 559-566.
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This study demonstrated a technique using forward osmosis (FO) to pre-concentrate the organic matter in raw wastewater, thereby transforming low strength wastewater into an anaerobically digestible solution. The chemical oxygen demand (COD) of raw wastewater was concentrated up to approximately eightfold at a water recovery of 90%. Thus, even low strength wastewater could be pre-concentrated by FO to the range suitable for biogas production via anaerobic treatment. Excessive salinity accumulation in pre-concentrated wastewater was successfully mitigated by adopting ionic organic draw solutes, namely, sodium acetate, and EDTA-2Na. These two draw solutes are also expected to benefit the digestibility of the pre-concentrated wastewater compared to the commonly used draw solute sodium chloride. Significant membrane fouling was observed when operating at 90% water recovery using raw wastewater. Nevertheless, membrane fouling was reversible and was effectively controlled by optimising the hydrodynamic conditions of the cross-flow FO system.
Chen, C., Guo, W. & Ngo, H. 2016, 'Advances in granular growth anaerobic membrane bioreactor (G-AnMBR) for low strength wastewater treatment', Journal of Energy and Environmental Sustainability, vol. 1, pp. 77-83.
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Wu, H., Lin, L., Zhang, J., Guo, W., Liang, S. & Liu, H. 2016, 'Purification ability and carbon dioxide flux from surface flow constructed wetlands treating sewage treatment plant effluent.', Bioresource technology.
In this study, a two-year experiment was carried out to investigate variation of carbon dioxide (CO2) flux from free water surface constructed wetlands (FWS CW) systems treating sewage treatment plant effluent, and treatment performance was also evaluated. The better 74.6-76.6% COD, 92.7-94.4% NH4(+)-N, 60.1-84.7% TN and 49.3-70.7% TP removal efficiencies were achieved in planted CW systems compared with unplanted systems. The planted CW was a net CO2 sink, while the unplanted CW was a net CO2 source in the entire study period. An obvious annual and seasonal variability of CO2 fluxes from different wetland systems was also presented with the average CO2 flux ranging from -592.83mgm(-2)h(-1) to 553.91mgm(-2)h(-1) during 2012-2013. In addition, the net exchange of CO2 between CW systems and the atmosphere was significantly affected by air temperature, and the presence of plants also had the significant effect on total CO2 emissions.
Zhang, X., Chen, X., Zhang, C., Wen, H., Guo, W. & Ngo, H.H. 2016, 'Effect of filling fraction on the performance of sponge-based moving bed biofilm reactor.', Bioresource technology.
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Cubic-shaped polyurethane sponges (151515mm) in the form of biofilm carriers were used in a moving bed biofilm reactor (MBBR) for treating synthetic domestic wastewater. Results indicated there was no significant difference in total organic carbon (TOC) and ammonia (NH4(+)-N) removal at different filling fractions. Three reactors exhibited high removal efficiencies of over 93% TOC and 95% NH4(+)-N on average at an HRT of 12h and aeration flow of 0.09m(3)/h. However, total nitrogen (TN) removal and simultaneous nitrification and denitrification (SND) increased with increasing the filling fraction. TN removal averaged at 77.2, 85.5% and 86.7% in 10%, 20% and 30% filling fraction reactor, respectively. Correspondingly, SND were 85.5&plusmn;8.7%, 91.3&plusmn;9.4% and 93.3&plusmn;10.2%. Moreover, it was observed that sponge carriers in the 20% filling fraction reactor achieved the maximum biomass amount per gram sponge, followed by the 10% and 30% filling fraction reactors.
Khan, M.A., Ngo, H.H., Guo, W.S., Liu, Y., Nghiem, L.D., Hai, F.I., Deng, L.J., Wang, J. & Wu, Y. 2016, 'Optimization of process parameters for production of volatile fatty acid, biohydrogen and methane from anaerobic digestion.', Bioresource technology, vol. 219, pp. 738-748.
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The anaerobic digestion process has been primarily utilized for methane containing biogas production over the past few years. However, the digestion process could also be optimized for producing volatile fatty acids (VFAs) and biohydrogen. This is the first review article that combines the optimization approaches for all three possible products from the anaerobic digestion. In this review study, the types and configurations of the bioreactor are discussed for each type of product. This is followed by a review on optimization of common process parameters (e.g. temperature, pH, retention time and organic loading rate) separately for the production of VFA, biohydrogen and methane. This review also includes additional parameters, treatment methods or special additives that wield a significant and positive effect on production rate and these products' yield.
Liu, Y., Peng, L., Ngo, H.H., Guo, W., Wang, D., Pan, Y., Sun, J. & Ni, B.J. 2016, 'Evaluation of Nitrous Oxide Emission from Sulfide- and Sulfur-Based Autotrophic Denitrification Processes.', Environmental science & technology, vol. 50, no. 17, pp. 9407-9415.
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Recent studies have shown that sulfide- and sulfur-based autotrophic denitrification (AD) processes play an important role in contributing to nitrous oxide (N2O) production and emissions. However, N2O production is not recognized in the current AD models, limiting their ability to predict N2O accumulation during AD. In this work, a mathematical model is developed to describe N2O dynamics during sulfide- and sulfur-based AD processes for the first time. The model is successfully calibrated and validated using N2O data from two independent experimental systems with sulfide or sulfur as electron donors for AD. The model satisfactorily describes nitrogen reductions, sulfide/sulfur oxidation, and N2O accumulation in both systems. Modeling results revealed substantial N2O accumulation due to the relatively low N2O reduction rate during both sulfide- and sulfur-based AD processes. Application of the model to simulate long-term operations of activated sludge systems performing sulfide- and sulfur-based AD processes indicates longer sludge retention time reduced N2O emission. For sulfide-based AD process, higher initial S/N ratio also decreased N2O emission but with a higher operational cost. This model can be a useful tool to support process operation optimization for N2O mitigation during AD with sulfide or sulfur as electron donor.
Zhang, Q.H., Yang, W.N., Ngo, H.H., Guo, W., Jin, P.K., Dzakpusa, M., Yang, S.J., Wang, Q., Wang, X.C. & Ao, D. 2016, 'Current status of urban wastewater treatment plants in China', Environment International, vol. 92-93, pp. 11-22.
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The study reported and analyzed the current state of wastewater treatment plants (WWTPs) in urban China from the perspective of treatment technologies, pollutant removals, operating load and efuent discharge standards. By the end of 2013, 3508 WWTPs have been built in 31 provinces and cities in China with a total treatment ca- pacity of 1.48 108 m3/d. The uneven population distribution between China's east and west regions has resulted in notably different economic development outcomes. The technologies mostly used in WWTPs are AAO and ox- idation ditch, which account for over 50% of the existing WWTPs. According to statistics, the efciencies of COD and NH3&#8211;N removal are good in 656 WWTPs in 70 cities. The overall average COD removal is over 88% with few regional differences. The average removal efciency of NH3&#8211;N is up to 80%. Large differences exist between the operating loads applied in different WWTPs. The average operating loading rate is approximately 83%, and 52% of WWTPs operate at loadings of b 80%, treating up to 40% of the wastewater generated. The implementation of discharge standards has been low. Approximately 28% of WWTPs that achieved the Grade I-A Discharge Stan- dard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918&#8211;2002) were constructed after 2010. The sludge treatment and recycling rates are only 25%, and approximately 15% of wastewater is inefciently treated. Approximately 60% of WWTPs have capacities of 1 104 m3/d&#8211;5 104 m3/d. Relatively high energy consumption is required for small-scale processing, and the utilization rate of recycled wastewater is low. The challenges of WWTPs are discussed with the aim of developing rational criteria and appropriate technologies for water recycling. Suggestions regarding potential technical and administrative measures are provided.
Wang, S., Guo, J., Lian, J., Ngo, H.H., Guo, W., Liu, Y. & Song, Y. 2016, 'Rapid start-up of the anammox process by denitrifying granular sludge and the mechanism of the anammox electron transport chain', Biochemical Engineering Journal, vol. 115, pp. 101-107.
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Guo, J., Wang, S., Lian, J., Ngo, H.H., Guo, W., Liu, Y. & Song, Y. 2016, 'Rapid start-up of the anammox process: Effects of five different sludge extracellular polymeric substances on the activity of anammox bacteria.', Bioresource technology, vol. 220, pp. 641-646.
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This study investigated the rapid start-up of the anaerobic ammonium oxidation (anammox) strategy by inoculating different biomass ratios of denitrifying granular sludge and anammox bacteria. The results demonstrated that two reactors (R1 and R2) were rapidly and successfully started-up on days 25 and 28, respectively, with nitrogen removal rates (NRRs) of 0.70kg/(m(3)d) and 0.72kg/(m(3)d) at biomass ratios of 10:1 (R1) and 50:1 (R2). The explanation for rapid start-up was found by examining the effect of five different sludge extracellular polymeric substances (EPS) on the activity of anammox bacteria in the batch experiments. Batch experiments results first demonstrated that the denitrification sludge EPS (DS-EPS) enhanced the anammox bacteria activity the most, and NO2(-)-N, NH4(+)-N removal rates were 1.88- and 1.53-fold higher than the control with optimal DS-EPS volume of 10mL. The rapid start-up strategy makes possible the application of anammox to practical engineering.
Duc Nguyen, D., Ngo, H.H., Guo, W., Nguyen, T.T., Chang, S.W., Jang, A. & Yoon, Y.S. 2016, 'Can electrocoagulation process be an appropriate technology for phosphorus removal from municipal wastewater?', Science of the Total Environment, vol. 563–564, pp. 549-556.
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This paper evaluated a novel pilot scale electrocoagulation (EC) system for improving total phosphorus (TP) removal from municipal wastewater. This EC system was operated in continuous and batch operating mode under differing conditions (e.g. flow rate, initial concentration, electrolysis time, conductivity, voltage) to evaluate correlative phosphorus and electrical energy consumption. The results demonstrated that the EC system could effectively remove phosphorus to meet current stringent discharge standards of less than 0.2 mg/L within 2 to 5 min. This target was achieved in all ranges of initial TP concentrations studied. It was also found that an increase in conductivity of solution, voltages, or electrolysis time, correlated with improved TP removal efficiency and reduced specific energy consumption. Based on these results, some key economic considerations, such as operating costs, cost-effectiveness, product manufacturing feasibility, facility design and retrofitting, and program implementation are also discussed. This EC process can conclusively be highly efficient in a relatively simple, easily managed, and cost-effective for wastewater treatment system.
Deng, L., Guo, W., Ngo, H.H., Zhang, H., Wang, J., Li, J., Xia, S. & Wu, Y. 2016, 'Biofouling and control approaches in membrane bioreactors.', Bioresour Technol, vol. 221, pp. 656-665.
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Membrane fouling (especially biofouling) as a critical issue during membrane reactor (MBR) operation has attracted much attention in recent years. Although previous review papers have presented different aspects of MBR's fouling when treating various wastewaters, the information related to biofouling in MBRs has only simply or partially reviewed. This work attempts to give a more comprehensive and elaborate explanation of biofilm formation, biofouling factors and control approaches by addressing current achievements. This also suggests to a better way in controlling biofouling by developing new integrated MBR systems, novel flocculants and biomass carriers.
Nguyen, D.D., Chang, S.W., Jeong, S.Y., Jeung, J., Kim, S., Guo, W. & Ngo, H.H. 2016, 'Dry thermophilic semi-continuous anaerobic digestion of food waste: Performance evaluation, modified Gompertz model analysis, and energy balance', ENERGY CONVERSION AND MANAGEMENT, vol. 128, pp. 203-210.
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Xie, S., Hai, F.I., Zhan, X., Guo, W., Ngo, H.H., Price, W.E. & Nghiem, L.D. 2016, 'Anaerobic co-digestion: A critical review of mathematical modelling for performance optimization.', Bioresour Technol, vol. 222, pp. 498-512.
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Anaerobic co-digestion (AcoD) is a pragmatic approach to simultaneously manage organic wastes and produce renewable energy. This review demonstrates the need for improving AcoD modelling capacities to simulate the complex physicochemical and biochemical processes. Compared to mono-digestion, AcoD is more susceptible to process instability, as it operates at a higher organic loading and significant variation in substrate composition. Data corroborated here reveal that it is essential to model the transient variation in pH and inhibitory intermediates (e.g. ammonia and organic acids) for AcoD optimization. Mechanistic models (based on the ADM1 framework) have become the norm for AcoD modelling. However, key features in current AcoD models, especially relationships between system performance and co-substrates' properties, organic loading, and inhibition mechanisms, remain underdeveloped. It is also necessary to predict biogas quantity and composition as well as biosolids quality by considering the conversion and distribution of sulfur, phosphorus, and nitrogen during AcoD.
Luo, L., Wang, X.C., Ngo, H.H. & Guo, W. 2016, 'Thermodynamic entropy of organic oxidation in the water environment: experimental evaluation compared to semi-empirical calculation.', Environ Sci Pollut Res Int, vol. 23, no. 21, pp. 21350-21359.
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Residual organic matters in the secondary effluent are usually less biodegradable in terms of the total organic carbon content, and when discharged into a receiving water body, their further decomposition most likely mainly occurs due to chemical oxidation. Using this scenario, a semi-empirical method was previously developed to calculate the thermodynamic entropy of organic oxidation to quantitatively evaluate the impact of organic discharge on the water environment. In this study, the relationship between the entropy increase (SC) and excess organic mass (TOC) was experimentally verified via combustion heat measurement using typical organic chemicals and mixtures. For individual organic chemicals, a linear relationship was detected between SC and TOC with the same proportionality coefficient, 54.0&nbsp;kJ/g, determined in the previous semi-empirical relationship. For the organic mixtures, a linear relationship was also identified; however, the proportionality coefficient was 69.2&nbsp;kJ/g, indicating an approximately 28&nbsp;% increase in the oxidation heat required to decompose the same organic mass. This increase in energy can likely be attributed to the synergistic effects of hydrogen bonding, hydrophobic interactions, - interactions, and van der Waals interactions between functional groups of different organic compounds. Intermolecular interactions may result in 17-32&nbsp;% more dissociation energy for organic mixtures compared to the organic components' chemical structures. Because organics discharged into a water body are always a mixture of organic compounds, the proportionality coefficient obtained using organic mixtures should be adopted to modify the previously proposed semi-empirical equation.
Wu, Y., Wang, J., Zhang, H., Ngo, H.H., Guo, W. & Zhang, N. 2016, 'The impact of gas slug flow on microfiltration performance in an airlift external loop tubular membrane reactor', RSC Advances, vol. 6, no. 110, pp. 109067-109075.
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Sivagurunathan, P., Kumar, G., Kim, S.-.H., Kobayashi, T., Xu, K.-.Q., Guo, W. & Ngo, H.H. 2016, 'Enhancement Strategies for Hydrogen Production from Wastewater: A Review', CURRENT ORGANIC CHEMISTRY, vol. 20, no. 26, pp. 2744-2752.
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Jegatheesan, J.V., Chiemchaisri, C., Shu, L. & Guo, W. 2016, 'Special issue on Challenges in Environmental Science and Engineering (CESE-2015)', Bioresource Technology, vol. 210, pp. 1-1.
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Pham, T.T.N., Mainali, B., Ngo, H.H., Guo, W., Listowski, A., O'Halloran, K., Miechel, C. & Corby, N. 2015, 'Effect of heavy metals in recycled water used for household laundry on quality of cloth and washing machine', DESALINATION AND WATER TREATMENT, vol. 54, no. 1, pp. 178-190.
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Wu, H., Fan, J., Zhang, J., Ngo, H.H., Guo, W., Hu, Z. & Liang, S. 2015, 'Decentralized domestic wastewater treatment using intermittently aerated vertical flow constructed wetlands: impact of influent strengths.', Bioresource technology, vol. 176, pp. 163-168.
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In this study, the removal performances of organic pollutants and nitrogen in vertical flow constructed wetlands (VFCWs) with and without intermittent aeration fed with different strengths of influent were evaluated as a possible treatment for decentralized domestic wastewater in northern China. The intermittent aeration strategy not only significantly increased removal efficiencies of organic pollutants and ammonium nitrogen (NH4(+)-N), but also successfully created alternate aerobic and anaerobic conditions resulting in high total nitrogen (TN) removal. Moreover, increasing influent strength did not affect the removal efficiencies of organic matters and nitrogen in aerated VFCWs. Compared with non-aerated VFCWs, much higher removal of organic pollutants (96%), NH4(+)-N (98%), and TN (85%) was obtained simultaneously in intermittent aeration VFCWs, especially at high influent strengths. The results suggest that the intermittent aeration could be an appropriate strategy for achieving the high removal performance in VFCWs, especially for in-situ treatment of high strength decentralized domestic wastewaters.
Wang, Z., Liu, G., Zheng, H., Li, F., Ngo, H.H., Guo, W., Liu, C., Chen, L. & Xing, B. 2015, 'Investigating the mechanisms of biochar's removal of lead from solution.', Bioresource technology, vol. 177, pp. 308-317.
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The objective of this study was to investigate the relationship between Pb(2+) adsorption and physicochemical properties of biochars produced at different pyrolytic temperatures. Ten biochars were prepared from peanut shell (PS) and Chinese medicine material residue (MR) at 300-600&deg;C. Adsorption kinetics and isotherms were determined, and the untreated and Pb(2+)-loaded biochars were analyzed by FTIR, SEM-EDX and XRD. Functional groups complexation, Pb(2+)- interaction and precipitation with minerals jointly contributed to Pb(2+) adsorption on these biochars. New mineral precipitates (e.g., Pb2(SO4)O and Pb4(CO3)2(SO4)(OH)2) formed during Pb(2+) sorption. For high-temperature biochars (500&deg;C), Pb(2+) sorption via complexation reduced, but the contribution of Pb(2+)- interaction was enhanced. Dramatic reduction of Pb(2+) sorption on demineralized biochars indicated the dominant role of minerals. These results are useful for screening effective biochars as engineered sorbents to remove or immobilize Pb(2+) in polluted water and soil.
Luo, W., Hai, F.I., Kang, J., Price, W.E., Guo, W., Ngo, H.H., Yamamoto, K. & Nghiem, L.D. 2015, 'Effects of salinity build-up on biomass characteristics and trace organic chemical removal: implications on the development of high retention membrane bioreactors.', Bioresource technology, vol. 177, pp. 274-281.
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This study investigated the impact of salinity build-up on the performance of membrane bioreactor (MBR), specifically in terms of the removal and fate of trace organic chemicals (TrOCs), nutrient removal, and biomass characteristics. Stepwise increase of the influent salinity, simulating salinity build-up in high retention MBRs, adversely affected the metabolic activity in the bioreactor, thereby reducing organic and nutrient removal. The removal of hydrophilic TrOCs by MBR decreased due to salinity build-up. By contrast, with the exception of 17-ethynylestradiol, the removal of all hydrophobic TrOCs was not affected at high salinity. Moreover, salinity build-up had negligible impact on the residual accumulation of TrOCs in the sludge phase except for a few hydrophilic compounds. Additionally, the response of the biomass to salinity stress also dramatically enhanced the release of both soluble microbial products (SMP) and extracellular polymeric substances (EPS), leading to severe membrane fouling.
Wang, Q., Xie, H., Zhang, J., Liang, S., Ngo, H.H., Guo, W., Liu, C., Zhao, C. & Li, H. 2015, 'Effect of plant harvesting on the performance of constructed wetlands during winter: radial oxygen loss and microbial characteristics', Environmental Science and Pollution Research, vol. 22, no. 10, pp. 7476-7484.
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&copy; 2014, Springer-Verlag Berlin Heidelberg. The aboveground tissue of plants is important for providing roots with constant photosynthetic resources. However, the aboveground biomass is usually harvested before winter to maintain the permanent removal of nutrients. In this work, the effects of harvest on plants' involvement in oxygen input as well as in microbial abundance and activity were investigated in detail. Three series of constructed wetlands with integrated plants ('unharvested), harvested plants ('harvested), and fully cleared plants ('cleared) were set up. Better performance was found in the unharvested units, with the radial oxygen loss (ROL) rates ranging from 0.05 to 0.59&nbsp;mol O<inf>2</inf>/h/plant, followed by the harvested units that had relatively lower ROL rates (0.01 to 0.52&nbsp;mol O<inf>2</inf>/h/plant). The cleared units had the lowest removal efficiency, which had no rhizome resources from the plants. The microbial population and activity were highest in the unharvested units, followed by the harvested and cleared units. Results showed that bacterial abundances and enhanced microbial activity were ten times higher on root surfaces compared with sands. These results indicate that late autumn harvesting of the aboveground biomass exhibited negative effects on plant ROL as well as on the microbial population and activity during the following winter.
Gao, T., Wang, X.C., Chen, R., Ngo, H.H. & Guo, W. 2015, 'Disability adjusted life year (DALY): a useful tool for quantitative assessment of environmental pollution.', The Science of the total environment, vol. 511, pp. 268-287.
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Disability adjusted life year (DALY) has been widely used since 1990s for evaluating global and/or regional burden of diseases. As many environmental pollutants are hazardous to human health, DALY is also recognized as an indicator to quantify the health impact of environmental pollution related to disease burden. Based on literature reviews, this article aims to give an overview of the applicable methodologies and research directions for using DALY as a tool for quantitative assessment of environmental pollution. With an introduction of the methodological framework of DALY, the requirements on data collection and manipulation for quantifying disease burdens are summarized. Regarding environmental pollutants hazardous to human beings, health effect/risk evaluation is indispensable for transforming pollution data into disease data through exposure and dose-response analyses which need careful selection of models and determination of parameters. Following the methodological discussions, real cases are analyzed with attention paid to chemical pollutants and pathogens usually encountered in environmental pollution. It can be seen from existing studies that DALY is advantageous over conventional environmental impact assessment for quantification and comparison of the risks resulted from environmental pollution. However, further studies are still required to standardize the methods of health effect evaluation regarding varied pollutants under varied circumstances before DALY calculation.
Vo, T., Ngo, H., Guo, W., Zhou, J., Listowski, A., Du, B., Wei, Q. & Bui, X. 2015, 'Stormwater quality management in rail transportation — Past, present and future', Science of The Total Environment, vol. 512-513, pp. 353-363.
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Railways currently play an important role in sustainable transportation systems, owing to their substantial carrying capacity, environmental friendliness and land-saving advantages. Although total pollutant emissions from railway systems are far less than that of automobile vehicles, the pollution from railway operations should not be underestimated. To date, both scientific and practical papers dealing with stormwater management for rail tracks have solely focused on its drainage function. Unlike roadway transport, the potential of stormwater pollution from railway operations is currently mishandled. There have been very few studies into the impact of its operations on water quality. Hence, upon the realisation on the significance of nonpoint source pollution, stormwater management priorities should have been re-evaluated. This paper provides an examination of past and current practices of stormwater management in the railway industry, potential sources of stormwater pollution, obstacles faced in stormwater management and concludes with strategies for future management directions.
Tran, V.S., Ngo, H.H., Guo, W., Zhang, J., Liang, S., Ton-That, C. & Zhang, X. 2015, 'Typical low cost biosorbents for adsorptive removal of specific organic pollutants from water', BIORESOURCE TECHNOLOGY, vol. 182, pp. 353-363.
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Li, X., Zhang, H., Hou, Y., Gao, Y., Li, J., Guo, W. & Ngo, H.H. 2015, 'In situ investigation of combined organic and colloidal fouling for nanofiltration membrane using ultrasonic time domain reflectometry', Desalination, vol. 362, pp. 43-51.
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Wu, H., Zhang, J., Ngo, H.H., Guo, W., Hu, Z., Liang, S., Fan, J. & Liu, H. 2015, 'A review on the sustainability of constructed wetlands for wastewater treatment: Design and operation.', Bioresour Technol, vol. 175, pp. 594-601.
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Constructed wetlands (CWs) have been used as a green technology to treat various wastewaters for several decades. CWs offer a land-intensive, low-energy, and less-operational-requirements alternative to conventional treatment systems, especially for small communities and remote locations. However, the sustainable operation and successful application of these systems remains a challenge. Hence, this paper aims to provide and inspire sustainable solutions for the performance and application of CWs by giving a comprehensive review of CWs' application and the recent development on their sustainable design and operation for wastewater treatment. Firstly, a brief summary on the definition, classification and application of current CWs was presented. The design parameters and operational conditions of CWs including plant species, substrate types, water depth, hydraulic load, hydraulic retention time and feeding mode related to the sustainable operation for wastewater treatments were then discussed. Lastly, future research on improving the stability and sustainability of CWs were highlighted.
Wei, D., Wang, B., Ngo, H.H., Guo, W., Han, F., Wang, X., Du, B. & Wei, Q. 2015, 'Role of extracellular polymeric substances in biosorption of dye wastewater using aerobic granular sludge.', Bioresource technology, vol. 185, pp. 14-20.
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In this study, the role of extracellular polymeric substances (EPS) in biosorption of dye wastewater was evaluated using aerobic granular sludge as biosorbent. Based on the experimental data, the removal efficiencies of methylene blue (MB) by EPS and Sludge were 9.38 and 80.72%, respectively, implying that EPS made a certain contribution for MB removal. The adsorption rates of EPS, Sludge, and total Sludge+EPS for MB were better fitted with pseudo-second order kinetic model, and the equilibrium adsorption isotherm data agreed well with Langmuir model. The interaction between EPS and MB was explored by a combined three-dimensional excitation-emission matrix (3D-EEM) and synchronous fluorescence spectra. 3D-EEM indicated that protein- and humic acid-like substances were the main peaks of EPS, and gradually quenched with increased MB concentrations. According to synchronous fluorescence spectra, the main fluorescence quenching was caused by tryptophan residues, and the type belonged to a combined dynamic and static quenching.
Nguyen, N.C., Chen, S.-.S., Nguyen, H.T., Ngo, H.H., Guo, W., Hao, C.W. & Lin, P.-.H. 2015, 'Applicability of a novel osmotic membrane bioreactor using a specific draw solution in wastewater treatment.', The Science of the total environment, vol. 518-519, pp. 586-594.
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This study aims to develop a new osmotic membrane bioreactor by combining a moving bed biofilm reactor (MBBR) with forward osmosis membrane bioreactor (FOMBR) to treat wastewater. Ethylenediaminetetraacetic acid disodium salt coupled with polyethylene glycol tert-octylphenyl ether was used as an innovative draw solution in this membrane hybrid system (MBBR-OsMBR) for minimizing the reverse salt flux and maintaining a healthy environment for the microorganism community. The results showed that the hybrid system achieved a stable water flux of 6.94 L/m(2) h and low salt accumulation in the bioreactor for 68 days of operation. At a filling rate of 40% (by volume of the bioreactor) of the polyethylene balls used as carriers, NH4(+)-N and PO4(3-)-P were almost removed (>99%) while producing relatively low NO3(-)-N and NO2(-)-N in the effluent (e.g. <0.56 and 0.96 mg/L, respectively). Furthermore, from analysis based on scanning electron microscopy, Fourier transform infrared spectroscopy, and fluorescence emission-excitation matrix spectrophotometry, there was a thin gel-like fouling layer on the FO membrane, which composed of bacteria as well as biopolymers and protein-like substances. Nonetheless, the formation of these fouling layers of the FO membrane in MBBR-OsMBR was reversible and removed by a physical cleaning technique.
Zuthi, M.F.R., Ngo, H.H., Guo, W.S., Nghiem, L.D., Hai, F.I., Xia, S.Q., Zhang, Z.Q. & Li, J.X. 2015, 'Biomass viability: An experimental study and the development of an empirical mathematical model for submerged membrane bioreactor.', Bioresource technology, vol. 190, pp. 352-358.
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This study investigates the influence of key biomass parameters on specific oxygen uptake rate (SOUR) in a sponge submerged membrane bioreactor (SSMBR) to develop mathematical models of biomass viability. Extra-cellular polymeric substances (EPS) were considered as a lumped parameter of bound EPS (bEPS) and soluble microbial products (SMP). Statistical analyses of experimental results indicate that the bEPS, SMP, mixed liquor suspended solids and volatile suspended solids (MLSS and MLVSS) have functional relationships with SOUR and their relative influence on SOUR was in the order of EPS>bEPS>SMP>MLVSS/MLSS. Based on correlations among biomass parameters and SOUR, two independent empirical models of biomass viability were developed. The models were validated using results of the SSMBR. However, further validation of the models for different operating conditions is suggested.
Ansari, A.J., Hai, F.I., Guo, W., Ngo, H.H., Price, W.E. & Nghiem, L.D. 2015, 'Selection of forward osmosis draw solutes for subsequent integration with anaerobic treatment to facilitate resource recovery from wastewater.', Bioresource technology, vol. 191, pp. 30-36.
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Forward osmosis (FO) can be used to extract clean water and pre-concentrate municipal wastewater to make it amenable to anaerobic treatment. A protocol was developed to assess the suitability of FO draw solutes for pre-concentrating wastewater for potential integration with anaerobic treatment to facilitate resource recovery from wastewater. Draw solutes were evaluated in terms of their ability to induce osmotic pressure, water flux, and reverse solute flux. The compatibility of each draw solute with subsequent anaerobic treatment was assessed by biomethane potential analysis. The effect of each draw solute (at concentrations corresponding to the reverse solute flux at ten-fold pre-concentration of wastewater) on methane production was also evaluated. The results show that ionic organic draw solutes (e.g., sodium acetate) were most suitable for FO application and subsequent anaerobic treatment. On the other hand, the reverse solute flux of inorganic draw solutions could inhibit methane production from FO pre-concentrated wastewater.
Luo, Y., Jiang, Q., Ngo, H.H., Nghiem, L.D., Hai, F.I., Price, W.E., Wang, J. & Guo, W. 2015, 'Evaluation of micropollutant removal and fouling reduction in a hybrid moving bed biofilm reactor-membrane bioreactor system.', Bioresource technology, vol. 191, pp. 355-359.
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A hybrid moving bed biofilm reactor-membrane bioreactor (MBBR-MBR) system and a conventional membrane bioreactor (CMBR) were compared in terms of micropollutant removal efficiency and membrane fouling propensity. The results show that the hybrid MBBR-MBR system could effectively remove most of the selected micropollutants. By contrast, the CMBR system showed lower removals of ketoprofen, carbamazepine, primidone, bisphenol A and estriol by 16.2%, 30.1%, 31.9%, 34.5%, and 39.9%, respectively. Mass balance calculations suggest that biological degradation was the primary removal mechanism in the MBBR-MBR system. During operation, the MBBR-MBR system exhibited significantly slower fouling development as compared to the CMBR system, which could be ascribed to the wide disparity in the soluble microbial products (SMP) levels between MBBR-MBR (4.02-6.32 mg/L) and CMBR (21.78 and 33.04 mg/L). It is evident that adding an MBBR process prior to MBR treatment can not only enhance micropollutant elimination but also mitigate membrane fouling.
Ahmed, M.B., Zhou, J.L., Ngo, H.H. & Guo, W. 2015, 'Adsorptive removal of antibiotics from water and wastewater: Progress and challenges', SCIENCE OF THE TOTAL ENVIRONMENT, vol. 532, pp. 112-126.
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Nguyen, A.H., Ngo, H.H., Guo, W.S., Pham, T.Q., Li, F.M., Nguyen, T.V. & Bui, X.T. 2015, 'Adsorption of phosphate from aqueous solutions and sewage using zirconium loaded okara (ZLO): Fixed-bed column study', SCIENCE OF THE TOTAL ENVIRONMENT, vol. 523, pp. 40-49.
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Hau, T.N., Chen, S.-.S., Nguyen, C.N., Huu, H.N., Guo, W. & Li, C.-.W. 2015, 'Exploring an innovative surfactant and phosphate-based draw solution for forward osmosis desalination', JOURNAL OF MEMBRANE SCIENCE, vol. 489, pp. 212-219.
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Liu, H., Zhang, J., Ngo, H.H., Guo, W., Wu, H., Cheng, C., Guo, Z. & Zhang, C. 2015, 'Carbohydrate-based activated carbon with high surface acidity and basicity for nickel removal from synthetic wastewater', RSC Advances, vol. 5, no. 64, pp. 52048-52056.
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Wang, Y.X., Ngo, H.H. & Guo, W.S. 2015, 'Preparation of a specific bamboo based activated carbon and its application for ciprofloxacin removal.', Sci Total Environ, vol. 533, pp. 32-39.
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The studied bamboo based activated carbon (BbAC) with high specific surface area (SSA) and high micro pore volume was prepared from bamboo scraps by the combined activation of H3PO4 and K2CO3. The BbAC was characterized based on the N2 adsorption isotherm at 77K. The results showed that the SSA and pore volume of BbAC increased with increasing impregnation ratio and reached maxima at the impregnation ratio of 3:1 at 750&deg;C. Under these optimal conditions, the BbAC obtained could have a maximum SSA of 2237 m(2)/g and a maximum total pore volume of 1.23 cm(3)/g with the micro pore ratio of more than 90%. The adsorption performance of ciprofloxacin (CIP) on the BbAC was determined at 298 K. The Langmuir and Freundlich models were employed to describe the adsorption equilibrium and the kinetic data were fitted by pseudo first-order and pseudo second-order kinetic models. The results showed that the Langmuir model and the pseudo second-order kinetic model presented better fittings for the adsorption equilibrium and kinetics data, respectively. The maximum adsorption amount of CIP (613 mg/g) on the BbAC was much higher than the report in the literature. Conclusively, the BbAC could be a promising adsorption material for CIP removal from water.
Li, X., Li, J., Wang, H., Huang, X., He, B., Yao, Y., Wang, J., Zhang, H., Ngo, H.H. & Guo, W. 2015, 'A filtration model for prediction of local flux distribution and optimization of submerged hollow fiber membrane module', AIChE Journal, vol. 61, no. 12, pp. 4377-4386.
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Abdolali, A., Ngo, H.H., Guo, W., Zhou, J.L., Du, B., Wei, Q., Wang, X.C. & Nguyen, P.D. 2015, 'Characterization of a multi-metal binding biosorbent: Chemical modification and desorption studies', BIORESOURCE TECHNOLOGY, vol. 193, pp. 477-487.
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Shi, L., Wei, D., Ngo, H.H., Guo, W., Du, B. & Wei, Q. 2015, 'Application of anaerobic granular sludge for competitive biosorption of methylene blue and Pb(II): Fluorescence and response surface methodology.', Bioresour Technol, vol. 194, pp. 297-304.
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This study assessed the biosorption of anaerobic granular sludge (AGS) and its capacity as a biosorbent to remove Pb(II) and methylene blue (MB) from multi-components aqueous solution. It emerged that the biosorption data fitted well to the pseudo-second-order and Langmuir adsorption isotherm models in both single and binary systems. In competitive biosorption systems, Pb(II) and MB will suppress each other's biosorption capacity. Spectroscopic analysis, including Fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy were integrated to explain this interaction. Hydroxyl and amine groups in AGS were the key functional groups for sorption. Three-dimensional excitation-emission matrix (3D-EEM) implied that two main protein-like substances were identified and quenched when Pb(II) or MB were present. Response surface methodology (RSM) confirmed that the removal efficiency of Pb(II) and MB reached its peak when the concentration ratios of Pb(II) and MB achieved a constant value of 1.
Nguyen, H.T., Nguyen, N.C., Chen, S.-.S., Ngo, H.H., Guo, W. & Li, C.-.W. 2015, 'A new class of draw solutions for minimizing reverse salt flux to improve forward osmosis desalination.', The Science of the total environment, vol. 538, pp. 129-136.
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The applications of forward osmosis (FO) have been hindered because of the lack of an optimal draw solution. The reverse salt flux from the draw solution not only reduces the water flux but also increases the cost of draw solute replenishment. Therefore, in this study, Tergitol NP7 and NP9 with a long straight carbon chain and low critical micelle concentration (CMC) were coupled with highly charged ethylenediaminetetraacetic acid (EDTA) as an innovative draw solution to minimize reverse salt diffusion in FO for the first time. The results showed that the lowest reverse salt flux of 0.067 GMH was observed when 0.1M EDTA-2Na coupled with 15mM NP7 was used as a draw solution and deionized water was used as a feed solution in FO mode (active layer facing with the feed solution). This is due to the hydrophobic interaction between the tails of NP7 and the FO membrane, thus creating layers on the membrane surface and constricting the FO membrane pores. Moreover, 1M EDTA-2Na coupled with 15mM NP7 is promising as an optimal draw solution for brackish water and sea water desalination. Average water fluxes of 7.68, 6.78, and 5.95 LMH were achieved when brackish water was used as a feed solution (5, 10, and 20g/L NaCl), and an average water flux of 3.81 LMH was achieved when sea water was used as a feed solution (35g/L NaCl). The diluted draw solution was recovered using a nanofiltration (NF-TS80) membrane with a high efficiency of 95% because of the high charge and large size of the draw solution.
Wu, H., Fan, J., Zhang, J., Ngo, H.H., Guo, W., Liang, S., Hu, Z. & Liu, H. 2015, 'Strategies and techniques to enhance constructed wetland performance for sustainable wastewater treatment', Environmental Science and Pollution Research, vol. 22, no. 19, pp. 14637-14650.
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Constructed wetlands (CWs) have been used as an alternative to conventional technologies for wastewater treatment for more than five decades. Recently, the use of various modified CWs to improve treatment performance has also been reported in the literature. However, the available knowledge on various CW technologies considering the intensified and reliable removal of pollutants is still limited. Hence, this paper aims to provide an overview of the current development of CW strategies and techniques for enhanced wastewater treatment. Basic information on configurations and characteristics of different innovations was summarized. Then, overall treatment performance of those systems and their shortcomings were further discussed. Lastly, future perspectives were also identified for specialists to design more effective and sustainable CWs. This information is used to inspire some novel intensifying methodologies, and benefit the successful applications of potential CW technologies.
Guo, S., Qu, F., Ding, A., Bai, L., Li, G., Ngo, H.H., Guo, W. & Liang, H. 2015, 'Effects of poly aluminum chloride dosing positions on the performance of a pilot scale anoxic/oxic-membrane bioreactor (A/O-MBR)', Water Science & Technology, vol. 72, no. 5, pp. 689-695.
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The effects of poly aluminum chloride (PACl) dosing positions on the performance of a pilot scale anoxic/oxic membrane bioreactor were investigated. PACl dosage was optimized at 19.5 mg Al2O3/L by jar test. Nutrients removal efficiencies and sludge properties were systematically investigated during periods with no PACl dosing (phase I), with PACl dosing in oxic tank (phase II) and then in anoxic tank (phase III). The results showed that total phosphorus removal efficiency increased from 18 to 88% in phase II and 85% in phase III with less than 0.5 mg P/L in effluent. Ammonia nitrogen removal efficiencies reached 99% in all phases and chemical oxygen demand removal efficiencies reached 92%, 91% and 90% in the three phases, respectively. Total nitrogen removal efficiency decreased from 59% in phase I to 49% in phases II and III. Dosing PACl in the oxic tank resulted in smaller sludge particle size, higher zeta potential, better sludge settleability and lower membrane fouling rate in comparison with dosing PACl in the anoxic tank.
Ren, L.F., Liang, S., Ngo, H.H., Guo, W., Ni, S.Q., Liu, C., Zhao, Y.K. & Hira, D. 2015, 'Enhancement of anammox performance in a novel non-woven fabric membrane bioreactor (nMBR)', RSC Advances, vol. 5, no. 106, pp. 86875-86884.
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Liu, H., Zhang, J., Ngo, H.H., Guo, W., Wu, H., Guo, Z., Cheng, C. & Zhang, C. 2015, 'Effect on physical and chemical characteristics of activated carbon on adsorption of trimethoprim: Mechanisms study', RSC Advances, vol. 5, no. 104, pp. 85187-85195.
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Kong, J.-.J., Yue, Q.-.Y., Zhao, P., Gao, B.-.Y., Li, Q., Wang, Y., Ngo, H.H. & Guo, W.-.S. 2015, 'Comparative study on microstructure and surface properties of keratin- and lignocellulosic-based activated carbons', FUEL PROCESSING TECHNOLOGY, vol. 140, pp. 67-75.
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Deng, L., Guo, W., Ngo, H.H., Zuthi, M.F.R., Zhang, J., Liang, S., Li, J., Wang, J. & Zhang, X. 2015, 'Membrane fouling reduction and improvement of sludge characteristics by bioflocculant addition in submerged membrane bioreactor', Separation and Purification Technology, vol. 156, pp. 450-458.
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Wang, J., Yang, S., Guo, W., Ngo, H.H., Jia, H., Yang, J., Zhang, H. & Zhang, X. 2015, 'Characterization of fouling layers for in-line coagulation membrane fouling by apparent zeta potential', RSC Advances, vol. 5, no. 128, pp. 106087-106093.
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Zhou, L., Zhang, Z., Xia, S., Jiang, W., Ye, B., Xu, X., Gu, Z., Guo, W., Ngo, H., Meng, X., Fan, J. & Zhao, J. 2014, 'Effects of suspended titanium dioxide nanoparticles on cake layer formation in submerged membrane bioreactor', Bioresource Technology, vol. 152, pp. 101-106.
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Effects of the suspended titanium dioxide nanoparticles (TiO2 NPs, 50 mg/L) on the cake layer formation in a submerged MBR were systematically investigated. With nanometer sizes, TiO2 NPs were found to aggravate membrane pore blocking but postpone cake layer fouling. TiO2 NPs showed obvious effects on the structure and the distribution of the organic and the inorganic compounds in cake layer. Concentrations of fatty acids and cholesterol in the cake layer increased due to the acute response of bacteria to the toxicity of TiO2 NPs. Line-analysis and dot map of energy-dispersive X-ray were also carried out. Since TiO2 NPs inhibited the interactions between the inorganic and the organic compounds, the inorganic compounds (especially SiO2) were prevented from depositing onto the membrane surface. Thus, the postponed cake layer fouling was due to the changing features of the complexes on the membrane surface caused by TiO2 NPs.
Hau, N.T., Chen, S., Nguyen, N.C., Huang, K.Z., Ngo, H. & Guo, W. 2014, 'Exploration of EDTA sodium salt as novel draw solution in forward osmosis process for dewatering of high nutrient sludge', Journal Of Membrane Science, vol. 455, pp. 305-311.
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In this study, a hybrid forward osmosisnanofiltration (FO/NF) process was designed for dewatering high nutrient containing sludge and recovering draw solution with minimum energy as well as low fouling. A novel draw solution - EDTA sodium salt - was also systematically studied for dewatering process. Results show that using EDTA sodium salt produced higher water flux and lower reverse salt flux when compared to conventional inorganic salt (NaCl) at pH 8. The final sludge concentration reached 32,000 mg/L after 16 h of operation. Moreover, nutrient compounds in sludge were successfully removed by the FO membrane with a removal efficiency of approximately 97% of NH4-N, 90% of NO3-N, 97% of NO2-N and 99% of PO4-P, which was attributed to the multi-barrier layers of sludge forming on membrane surface and the steric effect of the FO membrane. The NF recovery of EDTA sodium salt indicated that all NF membranes performed well and TS-80 was the best among the tested membranes.
Mainali, B., Pham, N., Ngo, H., Guo, W., Listowski, A., O'Halloran, K., Miechel, C., Muthukaruppan, M. & Johnston, R.R. 2014, 'Introduction and feasibility assessment of laundry use of recycled water in dual reticulation systems in Australia', The Science of the Total Environment, vol. 470-471, pp. 34-43.
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Laundry is a potential new end use of recycled water in dual reticulation systems. Generally, the community is willing to accept this new end use if it can meet the concerns on health issues, durability of washing machine, cloth quality and aesthetic appearance. This study addresses all these major concerns thereby assisting in the introduction and promotion of this new end use in the existing and proposed dual reticulation systems. Five representative cloth materials were selected for washing in tap water and in recycled water for up to 50 wash cycles for comparative studies. The tearing/tensile strength tests were used for the assessment of cloth durability. ANOVA one way test was applied for the significance analysis (Tukey's test p b 0.05) which indicated that there is no significant change in the tensile/tearing strengths of washed cloth samples. Scanning electron microscope (SEM) images of the washed cloth samples found no distinct change in surface morphology. Textile colour analysis (CIEDE2000) analysed the variation in colour of the washed cloth samples and showed that the change in colour ?E ranges from 01 revealing no visible difference in colour of cloth samples. Langelier Saturation Index (LSI) was used as the indicator for predicting corrosive/scaling potential of recycled water. The LSI values ranged from +0.5 to -0.5, indicating no corrosive or scaling potential of recycled water. The microbiological study of the cloth samples washed in recycled water indicated that there was no contamination with representative bacteria. As the recycled water has similar effects like tap water on cloth and washing machine, it is safe to use for laundry.
Zuthi, M., Ngo, H., Guo, W., Chen, S., Nguyen, N.C., Deng, L.J. & Tran, T.D.C. 2014, 'An assessment of the effects of microbial products on the specific oxygen uptake in submerged membrane bioreactor', International Journal of Environmental, Ecological, Geological and Geophysical Engineering, vol. 8, no. 2, pp. 90-94.
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Sustaining a desired rate of oxygen transfer for microbial activity is a matter of major concern for biological wastewater treatment (MBR). The study reported in the paper was aimed at assessing the effects of microbial products on the specific oxygen uptake rate (SOUR) in a conventional membrane bioreactor (CMBR) and that in a sponge submerged MBR (SSMBR). The production and progressive accumulation of soluble microbial products (SMP) and bound-extracellular polymeric substances (bEPS) were affecting the SOUR of the microorganisms which varied at different stages of operation of the MBR systems depending on the variable concentrations of the SMP/bEPS. The effect of bEPS on the SOUR was stronger in the SSMBR compared to that of the SMP, while relative high concentrations of SMP had adverse effects on the SOUR of the CMBR system. Of the different mathematical correlations analyzed in the study, logarithmic mathematical correlations could be established between SOUR and bEPS in SSMBR, and similar correlations could also be found between SOUR and SMP concentrations in the CMBR.
Chen, Z., Ngo, H., Guo, W., Lim, R.P., Wang, X.C., O'Halloran, K., Listowski, A., Corby, N. & Miechel, C. 2014, 'A comprehensive framework for the assessment of new end uses in recycled water schemes', The Science of the Total Environment, vol. 470-471, pp. 44-52.
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Nowadays, recycled water has provided sufficient flexibility to satisfy short-term freshwater needs and increase the reliability of long-term water supplies in many water scarce areas, which becomes an essential component of integrated water resources management. However, the current applications of recycled water are still quite limited that are mainly associated with non-potable purposes such as irrigation, industrial uses, toilet flushing and car washing. There is a large potential to exploit and develop new end uses of recycled water in both urban and rural areas. This can greatly contribute to freshwater savings, wastewater reduction and water sustainability. Consequently, the paper identified the potentials for the development of three recycled water new end uses, household laundry, livestock feeding and servicing, and swimming pool, in future water use market. To validate the strengths of these new applications, a conceptual decision analytic framework was proposed. This can be able to facilitate the optional management strategy selection process and thereafter provide guidance on the future end use studies within a larger context of the community, processes, and models in decision-making. Moreover, as complex evaluation criteria were selected and taken into account to narrow down the multiple management alternatives, the methodology can successfully add transparency, objectivity and comprehensiveness to the assessment. Meanwhile, the proposed approach could also allow flexibility to adapt to particular circumstances of each case under study.
Chen, Z., Ngo, H., Guo, W., Pham, N., Lim, R.P., Wang, X.C., Miechel, C., O'Halloran, K., Listowski, A. & Corby, N. 2014, 'A new optional recycled water pre-treatment system prior to use in the household laundry', The Science of the Total Environment, vol. 476-447, pp. 513-521.
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With a constantly growing population, water scarcity becomes the limiting factor for further social and economic growth. To achieve a partial reduction in current freshwater demands and lessen the environmental loadings, an increasing trend in the water market tends to adopt recycled water for household laundries as a new recycled water application. The installation of a small pre-treatment unit for water purification can not only further improve the recycled water quality, but also be viable to enhance the public confidence and acceptance level on recycled water consumption. Specifically, this paper describes column experiments conducted using a 550 mm length bed of zeolite media as a one-dimensional flow reactor. The results show that the zeolite filter system could be a simple low-cost pre-treatment option which is able to significantly reduce the total hardness level of recycled water via effective ion exchange. Additionally, depending on the quality of recycled water required by end users, a new by-pass controller using a three-level operation switching mechanism is introduced. This approach provides householders sufficient flexibility to respond to different levels of desired recycled water quality and increase the reliability of long-term system operation. These findings could be beneficial to the smooth implementation of new end uses and expansion of the potential recycled water market. The information could also offer sound suggestions for future research on sustainable water management and governance.
Zhou, L., Zhang, Z., Jiang, W., Guo, W., Ngo, H., Meng, X., Fan, J., Zhao, J. & Xia, S. 2014, 'Effects of low-concentration Cr(VI) on the performance and the membrane fouling of a submerged membrane bioreactor in municipal wastewater treatment', Biofouling, vol. 30, no. 1, pp. 105-114.
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The effects of low-concentration Cr(VI) (0.4 mg l-1) on the performance of a submerged membrane bioreactor (SMBR) in the treatment of municipal wastewater, as well as membrane fouling were investigated. Compared with the SMBR for control municipal wastewater, the SMBR for Cr(VI)-containing municipal wastewater had a higher concentration of soluble microbial products (SMP) with lower molecular weights, and smaller sludge particle sizes. Furthermore, low-concentration Cr(VI) induced membrane fouling, especially irreversible membrane pore blocking, which markedly shortened the service life of the membrane.
Li, X., Li, J., Wang, J., Wang, H., He, B., Zhang, H., Guo, W. & Ngo, H. 2014, 'Experimental investigation of local flux distribution and fouling behavior in double-end and dead-end submerged hollow fiber membrane modules', Journal Of Membrane Science, vol. 453, pp. 18-26.
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A new experimental method was proposed to obtain local fluxes along the membrane fibers of double-end and dead-end submerged hollow fiber membrane modules (SHFMMs) and to investigate the impact of average operating flux, fiber length and filtration modes (dead-end and double-end filtration) on local flux distribution. The relationship between the local flux and fouling behavior was monitored through the development of local fouling during filtration of 5 g/L yeast suspension using the non-invasive ultrasonic technique. The experimental results showed that the local flux distribution in the double-end SHFMM was more uniform than that in the dead-end SHFMM at the same operating conditions. Furthermore, the local flux obtained near the upper suction end of the double-end SHFMM was higher than that near the lower suction end. The difference value between the maximum and minimum local fluxes decreased with the decrease of fiber length and average operating flux in the double-end SHFMM. In addition, the ultrasonic measurements revealed that the behavior of fouling deposition on the membrane surface was consistent with the local flux distribution, which led to the self-adjustment and redistribution of local flux during the operation.
Hossain, A., Ngo, H., Guo, W., Nguyen, V. & Vigneswaran, S. 2014, 'Performance of cabbage and cauliflower wastes for heavy metals removal', Desalination and Water Treatment, vol. 52, pp. 844-860.
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From this study, the cabbage and cauliflower, a well-known agro-waste were used as biosorbents for removing toxic lead(II) and cadmium(II) from water. A batch of experiments for both biosorbents indicated that the lead(II) and cadmium(II) sorption depended on pH (5.06.5), doses of biosorbents (38 g/L) and contact time (1545 min). The adsorption processes were fast, and equilibrium time was reached at 45 and 15 min for lead(II) and 45 and 30 min for cadmium(II) adsorption onto cabbage and cauliflower biosorbents, respectively. Both biosorbents showed higher preferences for lead(II) than cadmium(II) towards adsorption from a binary solution. Langmuir model was the best-predicted model, but threeparameter models (Redlich-Peterson, Koble Corrigan, Khan and SIPS) were shown good fitness with equilibrium data, and the adsorption coefficients indicate favourable adsorption. The maximum monolayer capacities for lead(II) were 60.57 and 47.63 mg/g onto cabbage and cauliflower biosorbents, respectively, which is higher than cadmium(II) adsorption (20.57 and 21.32 mg/g). Adsorption kinetic was multi-order and steps as it is followed the pseudo-second order and Avrami model. As a low-cost adsorbent, cabbage and cauliflower biosorbents could be preferable for the removal of heavy metals from water and wastewaters.
Guadie, A., Xia, S., Zhang, Z., Zeleke, J., Guo, W., Ngo, H. & Hermanowicz, S.W. 2014, 'Effect of intermittent aeration cycle on nutrient removal and microbial community in a fluidized bed reactor-membrane bioreactor combo system', Bioresource Technology, vol. 156, pp. 195-205.
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Effect of intermittent aeration cycle (IAC = 15/4560/60 min) on nutrient removal and microbial community structure was investigated using a novel fluidized bed reactormembrane bioreactor (FBRMBR) combo system. FBR alone was found more efficient for removing PO4-P (>85%) than NH4-N (<40%) and chemical oxygen demand (COD < 35%). However, in the combo system, COD and NH4-N removals were almost complete (>98%). Efficient nitrification, stable mixed liquor suspended solid and reduced transmembrane pressure was also achieved. Quantitative real-time polymerase chain reaction results of total bacteria 16S rRNA gene copies per mL of mixed-liquor varied from (2.48 &plusmn; 0.42) 109 initial to (2.74 &plusmn; 0.10) 108, (6.27 &plusmn; 0.16) 109 and (9.17 &plusmn; 1.78) 109 for 15/45, 45/15 and 60/60 min of IACs, respectively. The results of clone library analysis revealed that Proteobacteria (59%), Firmicutes (12%) and Bacteroidetes (11%) were the dominant bacterial group in all samples. Overall, the combo system performs optimum nutrient removal and host stable microbial communities at 45/15 min of IAC.
Liu, H., Liang, S., Gao, J., Ngo, H., Guo, W., Guo, Z., Wang, J. & Li, Y. 2014, 'Enhancement of Cr(VI) removal by modifying activated carbon developed from Zizania caduciflora with tartaric acid during phosphoric acid activation', Chemical Engineering Journal, vol. 246, pp. 168-174.
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Tartaric acid (TA) was employed to modify Zizania caduciflora (ZC)-based activated carbon during phosphoric acid activation for improving its Cr(VI) removal from aqueous solutions. The original activated carbon (AC) and TA-modified activated carbon (ACTA) were characterized by N2 adsorption/desorption, Boehms titration and X-ray photoelectron spectroscopy (XPS) analysis. The Cr(VI) removal abilities of AC and ACTA were evaluated by batch sorption experiments. The residual Cr(VI) and total Cr concentration were determined to investigated the ``Sorption-coupled reduction mechanism. Equilibrium data for the Cr(VI) removal on AC and ACTA were well described by the Freundlich model. The ACTA exhibited much higher Cr(VI) and total Cr sorption capacities than AC. After blocking of carboxyl and hydroxyl functional groups, the carbons showed obviously higher Cr(VI) and total Cr removal than the original AC and ACTA, indicating that electrostatic attraction played an important role on Cr(VI) removal. The higher Cr(VI) removal on ACTA was attributed to its higher amount of oxygen-containing functional groups, which provided more electrons for Cr(VI) reduction and more positive sites for the produced Cr(III) sorption.
Abdolali, A., Ngo, H., Guo, W., Lee, D., Tung, K. & Wang, X.C. 2014, 'Development and evaluation of a new multi-metal binding biosorbent', Bioresource Technology, vol. 160, pp. 98-106.
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A novel multi-metal binding biosorbent (MMBB) was developed by combining a group of three from the selective natural lignocellulosic agro-industrial wastes for effectively eliminating lead, cadmium, copper and zinc from aqueous solutions. Four MMBBs with different combinations (MMBB1: tea waste, corncob, sugarcane bagasse; MMBB2: tea waste, corncob and sawdust; MMBB3: tea waste, corncob and apple peel; MMBB4: tea waste, corncob and grape stalk) were evaluated. FTIR analysis for characterizing the MMBB2 explored that the MMBB2 contains more functional groups available for multi-metals binding. Comparing among the MMBBs as well as the single group biosorbents, MMBB2 was the best biosorbent with the maximum biosorption capacities of 41.48, 39.48, 94.00 and 27.23 mg/g for Cd(II), Cu(II), Pb(II) and Zn(II), respectively. After 5 times of desorption with CaCl2, CH3COOH and NaCl as eluent, the MMBB2 still remained excellent biosorptive capacity, so as it could be well regenerated for reuse and possible recovery of metals.
Luo, Y., Guo, W., Ngo, H., Nghiem, L.D., Hai, F.I., Kang, J., Xia, S., Zhang, Z. & Price, W.E. 2014, 'Removal and fate of micropollutants in a sponge-based moving bed bioreactor', Bioresource Technology, vol. 159, pp. 311-319.
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This study investigated the removal of micropollutants using polyurethane sponge as attached-growth carrier. Batch experiments demonstrated that micropollutants could adsorb to non-acclimatized sponge cubes to varying extents. Acclimatized sponge showed significantly enhanced removal of some less hydrophobic compounds (log D < 2.5), such as ibuprofen, acetaminophen, naproxen, and estriol, as compared with non-acclimatized sponge. The results for bench-scale sponge-based moving bed bioreactor (MBBR) system elucidated compound-specific variation in removal, ranging from 25.9% (carbamazepine) to 96.8% (-Estradiol 17-acetate) on average. In the MBBR system, biodegradation served as a major removal pathway for most compounds. However, sorption to sludge phase was also a notable removal mechanism of some persistent micropollutants. Particularly, carbamazepine, ketoprofen and pentachlorophenol were found at high concentrations (7.87, 6.05 and 5.55 &micro;g/g, respectively) on suspended biosolids. As a whole, the effectiveness of MBBR for micropollutant removal was comparable with those of activated sludge processes and MBRs.
Semblante, G.U., Hai, F.I., Ngo, H., Guo, W., You, S., Price, W.E. & Nghiem, L.D. 2014, 'Sludge cycling between aerobic, anoxic and anaerobic regimes to reduce sludge production during wastewater treatment: performance, mechanisms, and implications', Bioresource Technology, vol. 155, pp. 395-409.
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Alternate cycling of sludge in aerobic, anoxic, and anaerobic regimes is a promising strategy that can reduce the sludge yield of conventional activated sludge (CAS) by up to 50% with potentially lower capital and operating cost than physical- and/or chemical-based sludge minimisation techniques. The mechanisms responsible for reducing sludge yield include alterations to cellular metabolism and feeding behaviour (metabolic uncoupling, feasting/fasting, and endogenous decay), biological floc destruction, and predation on bacteria by higher organisms. Though discrepancies across various studies are recognisable, it is apparent that sludge retention time, oxygen-reduction potential of the anaerobic tank, temperature, sludge return ratio and loading mode are relevant to sludge minimisation by sludge cycling approaches. The impact of sludge minimisation on CAS operation (e.g., organics and nutrient removal efficiency and sludge settleability) is highlighted, and key areas requiring further research are also identified.
Wijekoon, K.C., Hai, F.I., Kang, J., Price, W.E., Guo, W., Ngo, H., Cath, T.Y. & Nghiem, L.D. 2014, 'A novel membrane distillation - thermophilic bioreactor (MDBR) system: Biological stability and trace organic compound removal', Bioresource Technology, vol. 159, pp. 334-341.
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The removal of trace organic compounds (TrOCs) by a novel membrane distillationthermophilic bioreactor (MDBR) system was examined. Salinity build-up and the thermophilic conditions to some extent adversely impacted the performance of the bioreactor, particularly the removal of total nitrogen and recalcitrant TrOCs. While most TrOCs were well removed by the thermophilic bioreactor, compounds containing electron withdrawing functional groups in their molecular structure were recalcitrant to biological treatment and their removal efficiency by the thermophilic bioreactor was low (053%). However, the overall performance of the novel MDBR system with respect to the removal of total organic carbon, total nitrogen, and TrOCs was high and was not significantly affected by the conditions of the bioreactor. All TrOCs investigated here were highly removed (>95%) by the MDBR system. Biodegradation, sludge adsorption, and rejection by MD contribute to the removal of TrOCs by MDBR treatment.
Ma, X.Y., Wang, X.C., Ngo, H., Guo, W., Wu, M.N. & Wang, N. 2014, 'Bioassay based luminescent bacteria: interferences, improvements, and applications', The Science of the Total Environment, vol. 468-469, pp. 1-11.
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Due to the merits of being time-saving, cost effective and simple operation, the luminescent bacteria toxicity assay (LBTA) has been widely used for environmental pollution monitoring. Based on numerous studies since 2007, this critical review aims to give an overview on the mechanisms, developments and applications of LBTA. Firstly, based on the introduction of the mechanisms of LBTA, this review shows the interferences from the characteristics of testing samples (such as inorganic nutrients, color, turbidity) and summarizes the improvements on pretreatment method, test methods and test systems in recent years. Regarding the factors that affect the toxicity prediction of single chemicals, the correlation between the toxicity index expressed asmedian effective concentration (EC50) and characters (such as Kow, the alkyl chain length, the anion and the cation) of known chemicals, especially the emerging ionic liquids (ILs), were given an in-depth discussion. The models for predicting the joint effect of mixtures to luminescent bacteria were also presented. For the factors that affect the toxicity of actual waters, the correlation of toxicity of actual samples to luminescent bacteria and their conventional indexes were discussed. Comparing the sensitivity of the LBTA with other bioassays could indicate the feasibility of the LBTA applied on specific samples. The summary on the application of LBTA to environmental samples has been made to find the future research direction.
Luo, Y., Guo, W., Ngo, H., Nghiem, L.D., Hai, F., Zhang, J., Liang, S. & Wang, X.C. 2014, 'A review on the occurrence of micropollutants in the aquatic environment and their fate and removal during wastewater treatment', The Science of the Total Environment, vol. 473-474, pp. 619-641.
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Micropollutants are emerging as a new challenge to the scientific community. This review provides a summary of the recent occurrence of micropollutants in the aquatic environment including sewage, surface water, groundwater and drinking water. The discharge of treated effluent from WWTPs is a major pathway for the introduction of micropollutants to surface water. WWTPs act as primary barriers against the spread of micropollutants. WWTP removal efficiency of the selected micropollutants in 14 countries/regions depicts compound-specific variation in removal, ranging from 12.5 to 100%. Advanced treatment processes, such as activated carbon adsorption, advanced oxidation processes, nanofiltration, reverse osmosis, and membrane bioreactors can achieve higher and more consistent micropollutant removal. However, regardless of what technology is employed, the removal of micropollutants depends on physico-chemical properties of micropollutants and treatment conditions. The evaluation of micropollutant removal from municipal wastewater should cover a series of aspects from sources to end uses. After the release of micropollutants, a better understanding and modeling of their fate in surface water is essential for effectively predicting their impacts on the receiving environment.
Abdolali, A., Guo, W., Ngo, H., Chen, S., Nguyen, N.C. & Tung, K. 2014, 'Typical lignocellulosic wastes and by-products for biosorption process in water and wastewater treatment: A critical review', Bioresource Technology, vol. 160, pp. 57-66.
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Biosorption on lignocellulosic wastes and byproducts has been identified as a proper alternative to the existing technologies applied for toxic metal ion and dye removal from wastewater streams. This paper deals with utilization of typical low cost wastes and by-products produced in different food agricultural and agroindustries as biosorbent and reviews the current state of studies on a wide variety of cheap biosorbents in natural and modified forms. The efficiency of each biosorbent has been also discussed with respect to the operating conditions (e.g. temperature, hydraulic residence time, initial metal concentration, biosorbent particle size and its dosage), chemical modification on sorption capacity and preparation methods, as well as thermodynamics and kinetics.
Hossain, M.D., Ngo, H., Guo, W., Nghiem, L.D., Hai, F.I., Vigneswaran, S. & Nguyen, V. 2014, 'Competitive adsorption of metals on cabbage waste from multi-metal solutions', Bioresource Technology, vol. 160, pp. 79-88.
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This study assessed the adsorption capacity of the agro-waste 'cabbage' as a biosorbent in single, binary, ternary and quaternary sorption systems with Cu(II), Pb(II), Zn(II) and Cd(II) ions. Dried and ground powder of cabbage waste (CW) was used for the sorption of metals ions. Carboxylic, hydroxyl, and amine groups in cabbage waste were found to be the key functional groups for metal sorption. The adsorption isotherms obtained could be well fitted to both the mono- and multi-metal models. In the competitive adsorption systems, cabbage waste adsorbed larger amount of Pb(II) than the other three metals. However, the presence of the competing ions suppressed the sorption of the target metal ions. Except the case of binary system of Cd(II)-Zn(II) and Cd(II)-Cu(II), there was a linear inverse dependency between the sorption capacities and number of different types of competitive metal ions.
Liu, H., Liang, S., Gao, J., Ngo, H., Guo, W., Guo, Z. & Li, Y. 2014, 'Development of biochars from pyrolysis of lotus stalks for Ni(II) sorption: using zinc borate as flame retardant', Journal Of Analytical And Applied Pyrolysis, vol. 107, pp. 336-341.
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In this work, zinc borate (ZB) was employed as flame retardant for preparation of biochar (BC). A series of BC samples were generated by varying the ZB to lotus stalks (LS) ratio (0.25, 0.5 and 1.0) under different temperatures (300, 350 and 400 ?C) for 1 h. The BCs were analyzed for their surface morphologies, surface areas, surface elemental compositions and yields. The results indicated that, after charring, ZB kept the structures of the produced BCs as its starting material (LS), dramatically enhancing their yields, and promoting their surface oxygen content. The BCs were used as adsorbent for removal of Ni(II) from aqueous solutions. Sorption of Ni(II) on the BCs was enhanced about 310 times compared with that of BCs derived from pyrolysis of LS without adding ZB.
Deng, L., Guo, W., Ngo, H., Zhang, J., Liang, S., Xia, S., Zhang, Z. & Li, J. 2014, 'A comparison study on membrane fouling in a sponge-submerged membrane bioreactor and a conventional membrane bioreactor', Bioresource Technology, vol. 165, pp. 69-74.
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This study compared membrane fouling in a sponge-submerged membrane bioreactor (SSMBR) and a conventional membrane bioreactor (CMBR) based on sludge properties when treating synthetic domestic wastewater. In the CMBR, soluble microbial products (SMP) in activated sludge were a major contributor for initial membrane fouling and presented higher concentration in membrane cake layer. Afterwards, membrane fouling was mainly governed by bound extracellular polymeric substances (EPS) in activated sludge, containing lower proteins but significantly higher polysaccharides. Sponge addition could prevent cake formation on membrane surface and pore blocking inside membrane, thereby alleviating membrane fouling. The SSMBR exhibited not only less growth of the biomass and filamentous bacteria, but also lower cake layer and pore blocking resistance due to lower bound EPS concentrations in activated sludge. Less membrane fouling in SSMBR were also attributed to larger particle size, higher zeta potential and relative hydrophobicity of sludge flocs.
Zhou, J., Siddiqui, E., Ngo, H. & Guo, W. 2014, 'Estimation of uncertainty in the sampling and analysis of polychlorinated biphenyls and polycyclic aromatic hydrocarbons from contaminated soil in Brighton, UK', The Science of the Total Environment, vol. 497-498, pp. 163-171.
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The heterogeneity of environmental samples is increasingly recognised, yet rarely examined in organic contamination investigations. In this study soil samples from an ex-landfill site in Brighton, UK were analysed for polychlorinated biphenyl (PCB) and polycyclic aromatic hydrocarbon (PAH) contamination by using a balanced sampling protocol. The analytical technique of gas chromatographymass spectrometry was found to be fit for purpose by the use of duplicate samples and the statistical analysis of variances, as well as of certified reference materials. The sampling uncertaintywas found to significantly overweigh the analytical uncertainty, by a factor of 3 and 6 for PCBs and PAHs, respectively. The soil samples showed a general trend of PCB concentration that was under the recommended target level of 20 ng/g dry weight. It is possible that one site alongside the main road may exceed the 20 ng/g target level, after taking into consideration the overall measurement uncertainty (70.8%). The PAH contamination was more severe, with seven sites potentially exceeding the effect-range medium concentrations. The soil samples with relatively high PCB and PAH concentrations were all taken from the grass verge, which also had the highest soil organic carbon content. The measurement uncertainty which was largely due to sampling can be reduced by sampling at a high resolution spacing of 17 m,which is recommended in future field investigations of soil organic contamination.
Vo, Ngo, H., Guo, W., Zhou, J., Nguyen, P.D., Listowski, A. & Wang, X.C. 2014, 'A mini-review on the impacts of climate change on wastewater reclamation and reuse', The Science of the Total Environment, vol. 494-495, pp. 9-17.
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To tackle current water insecurity concerns, wastewater reclamation and reuse have appeared as a promising candidate to conserve the valuable fresh water sources while increasing the efficiency of material utilization. Climate change, nevertheless, poses both opportunities and threats to the wastewater reclamation industry. Whereas it elevates the social perception on water-related issues and fosters an emerging water-reuse market, climate change simultaneously presents adverse impacts on the water reclamation scheme, either directly or indirectly. These effects were studied fragmentally in separate realms. Hence, this paper aims to link these studies for providing a thorough understanding about the consequences of the climate change on the wastewater reclamation and reuse. It initially summarizes contemporary treatment processes and their reuse purposes before carrying out a systematic analysis of available findings.
Nguyen, T., Ngo, H., Guo, W., Zhou, J., Wang, J., Liang, H. & Li, G. 2014, 'Phosphorus elimination from aqueous solution using 'zirconium loaded okara' as a biosorbent', Bioresource Technology, vol. 170, pp. 30-37.
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This work deals with the capture of phosphorus from aqueous solutions by biosorption onto zirconium loaded okara (ZLO). The batch-mode experiments were conducted to examine the effect of pH, biosorbent dose, initial phosphorus concentration, contact time, and temperature on the process. It was found that, the adsorption was most favored in the pH range of 26. The optimal doses for the adsorption, at initial phosphorus concentrations of 5, 10, 25, 50 mg/L were 2, 3, 7, 10 g/L, respectively. The maximum adsorption capacity of ZLO was approximately 44.13 mg PO4/g at 298 K. The phosphate removal was rapid, reaching 95% in 30 min. Freundlich model best fitted the equilibrium data, while Pseudo-second order model satisfactorily described the kinetic results. Thermodynamic analysis revealed feasible, spontaneous, and endothermic nature of the process. The research would be beneficial for developing a promising, eco-friendly phosphorus biosorbent from a plentiful AWB okara.
Ding, A., Liang, H., Qu, F., Bai, L., Li, G., Ngo, H. & Guo, W. 2014, 'Effect of granular activated carbon addition on the effluent properties and fouling potentials of membrane-coupled expanded granular sludge bed process', Bioresource Technology, vol. 170, pp. 240-246.
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To mitigate membrane fouling of membrane-coupled anaerobic process, granular activated carbon (GAC: 50 g/L) was added into an expanded granular sludge bed (EGSB). A short-term ultrafiltration test was investigated for analyzing membrane fouling potential and underlying fouling mechanisms. The results showed that adding GAC into the EGSB not only improved the COD removal efficiency, but also alleviated membrane fouling efficiently because GAC could help to reduce soluble microbial products, polysaccharides and proteins by 26.8%, 27.8% and 24.7%, respectively, compared with the control system. Furthermore, excitation emission matrix (EEM) fluorescence spectroscopy analysis revealed that GAC addition mainly reduced tryptophan protein-like, aromatic protein-like and fulvic-like substances. In addition, the resistance distribution analysis demonstrated that adding GAC primarily decreased the cake layer resistance by 53.5%. The classic filtration mode analysis showed that cake filtration was the major fouling mechanism for membrane-coupled EGSB process regardless of the GAC addition.
Ho, D.P., Ngo, H. & Guo, W. 2014, 'A mini review on renewable sources for biofuel', Bioresource Technology, vol. 169, pp. 742-749.
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Rapid growth in both global energy demand and carbon dioxide emissions associated with the use of fossil fuels has driven the search for alternative sources which are renewable and have a lower environmental impact. This paper reviews the availability and bioenergy potentials of the current biomass feedstocks. These include (i) food crops such as sugarcane, corn and vegetable oils, classified as the first generation feedstocks, and (ii) lignocellulosic biomass derived from agricultural and forestry residues and municipal waste, as second generation feedstocks. The environmental and socioeconomic limitations of the first generation feedstocks have placed greater emphasis on the lignocellulosic biomass, of which the conversion technologies still faces major constraints to full commercial deployment. Key technical challenges and opportunities of the lignocellulosic biomass-to-bioenergy production are discussed in comparison with the first generation technologies. The potential of the emerging third generation biofuel from algal biomass is also reviewed.
Nguyen, T., Ngo, H., Guo, W., Zhang, J., Liang, S., Lee, D., Nguyen, P. & Bui, X. 2014, 'Modification of agricultural waste/by-products for enhanced phosphate removal and recovery: Potential and obstacles', Bioresource Technology, vol. 169, pp. 750-762.
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There is a growing trend to employ agricultural waste/by-products (AWBs) as the substrates for the development of phosphate biosorbents. Nevertheless, due to the lack of anion binding sites, natural AWBs are usually inefficient in phosphate decontamination. Consequently, modification plays a vital role in improving phosphate sorptions property of raw AWBs. This review paper evaluates all existing methods of modification. The literatures indicate that modification can significantly improve phosphate removal ability of AWBs by retaining phosphate ion onto modified AWBs principally via ion exchange (electrostatic interaction) and ligand exchange mechanisms. So far, little work has been done on the beneficial use of modified AWBs for the phosphorus recovery from aqueous solutions. The poor recyclability of modified AWBs could be responsible for their limited application. Hence, further study is essential to search for novel, cost-effective, and green methods of modification.
Li, F., Lu, L., Zheng, X., Ngo, H., Liang, S., Guo, W. & Zhang, X. 2014, 'Enhanced nitrogen removal in constructed wetlands: Effects of dissolved oxygen and step-feeding', Bioresource Technology, vol. 169, pp. 395-402.
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Four horizontal subsurface flow constructed wetlands (HSFCWs), named HSFCW1 (three-stage, without step-feeding), HSFCW2 (three-stage, with step-feeding), HSFCW3 (five-stage, without step-feeding) and HSFCW4 (five-stage, with step-feeding) were designed to investigate the effects of dissolved oxygen (DO) and step-feeding on nitrogen removal. High removal of 90.9% COD, 99.1% ammonium nitrogen and 88.1% total nitrogen (TN) were obtained simultaneously in HSFCW4 compared with HSFCW13. The excellent TN removal of HSFCW4 was due to artificial aeration provided sufficient DO for nitrification and the favorable anoxic environment created for denitrification. Step-feeding was a crucial factor because it provided sufficient carbon source (high COD: nitrate ratio of 14.3) for the denitrification process. Microbial activities and microbial abundance in HSFCW4 was found to be influenced by DO distribution and step-feeding, and thus improve TN removal. These results suggest that artificial aeration combined with step-feeding could achieve high nitrogen removal in HSFCWs.
Nguyen, T., Ngo, H., Guo, W., Nguyen, V., Zhang, J., Liang, S., Chen, S. & Nguyen, N.C. 2014, 'A comparative study on different metal loaded soybean milk by-product 'okara' for biosorption of phosphorus from aqueous solution', Bioresource Technology, vol. 169, pp. 291-298.
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Cationization of agricultural by-products using metal salts is widely used to activate their phosphorous capture ability. This study developed three kinds ofnew metal loaded soybean milk by-product `okara for phosphorus biosorption. A comparative study among these biosorbents was carried out with respect to their performances in terms of affinity, stability and reusability. Zirconium loaded okara (ZLO) was found to have the highest affinity towards PO43- anions (47.88 mg/g), followed by iron/zirconium loaded okara IZLO (40.96 mg/g) and iron loaded okara ILO (16.39 mg/g). ZLO was successfully desorbed with 0.2 M NaOH and activated with 0.1 HCl prior to the next cycle. After five consecutive cycles, the efficiency of both adsorption and desorption of ZLO remained about 85% whilst no Zr(IV) leakage was observed. Conversely, IZLO and ILO suffered from vitalshortcomingssuch ashigh metal release and/or sharp reduction in PO43- sequestering capability after multi operation cycles.
Luo, W., Hai, F.I., Price, W.E., Guo, W., Ngo, H., Yamamoto, K. & Nghiem, L.D. 2014, 'High retention membrane bioreactors: challenges and opportunitie', Bioresource Technology, vol. 167, pp. 539-546.
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Extensive research has focussed on the development of novel high retention membrane bioreactor (HRMBR) systems for wastewater reclamation in recent years. HR-MBR integrates high rejection membrane separation with conventional biological treatment in a single step. High rejection membrane separation processes currently used in HR-MBR applications include nanofiltration, forward osmosis, and membrane distillation. In these HR-MBR systems, organic contaminants can be effectively retained, prolonging their retention time in the bioreactor and thus enhancing their biodegradation. Therefore, HR-MBR can offer a reliable and elegant solution to produce high quality effluent. However, there are several technological challenges associated with the development of HR-MBR, including salinity build-up, low permeate flux, and membrane degradation. This paper provides a critical review on these challenges and potential opportunities of HR-MBR for wastewater treatment and water reclamation, and aims to guide and inform future research on HR-MBR for fast commercialisation of this innovative technology.
Nguyen, L.N., Hai, F.I., Price, W.E., Leusch, F.D., Roddick, F., Ngo, H., Guo, W., Magram, S.F. & Nghiem, L.D. 2014, 'The effects of mediator and granular activated carbon addition on degradation of trace organic contaminants by an enzymatic membrane reactor', Bioresource Technology, vol. 167, pp. 169-177.
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The removal of four recalcitrant trace organic contaminants (TrOCs), namely carbamazepine, diclofenac, sulfamethoxazole and atrazine by laccase in an enzymatic membrane reactor (EMR) was studied. Laccases are not effective for degrading non-phenolic compounds; nevertheless, 2255% removal of these four TrOCs was achieved by the laccase EMR. Addition of the redox-mediator syringaldehyde (SA) to the EMR resulted in a notable dose-dependent improvement (1545%) of TrOC removal affected by inherent TrOC properties and loading rates. However, SA addition resulted in a concomitant increase in the toxicity of the treated effluent. A further 1425% improvement in aqueous phase removal of the TrOCs was consistently observed following a one-off dosing of 3 g/L granular activated carbon (GAC). Mass balance analysis reveals that this improvement was not due solely to adsorption but also enhanced biodegradation. GAC addition also reduced membrane fouling and the SA-induced toxicity of the effluent.
Hossain, A., Ngo, H., Guo, W., Zhang, J. & Liang, S. 2014, 'A laboratory study using maple leaves as a biosorbent for lead removal from aqueous solutions', Water Quality Research Journal of Canada, vol. 49, no. 3, pp. 195-209.
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This study tested the ability of maple leaf powder (MLP) to reduce the level of Pb(II) ions in aqueous solutions. As a biosorbent, MLP has a larger specific surface area (10.94 m2/g) and contains Pb(II) binding functional groups. The highest Pb(II) removals were achieved at pH of 6.2, particle size of less than 75 &micro;m, dose of 0.5 g, initial concentration of 10 mg/l and equilibrium time of >15 minutes. Thermodynamic results indicated that the Pb(II) adsorption process was spontaneous and exothermic. MLP biosorbent could be reused for five cycles after successfully recovery by 0.1N H2SO4. Both adsorption and desorption data fit well with Langmuir and Sips isotherm models (R2 0.9611.00). The Pb(II) adsorption and desorption capacities (qm) of MLP were up to 50.27 mg/g and 40.06 mg/g, respectively, for a 1 g dose at room temperature. Kinetics processes were rate controlling step and showed good fitness with the pseudo-second order and intraparticle diffusion models. Results suggest that multiple mechanisms (chelating bond, physisorption and chemisorption) are involved to adsorb the Pb(II) ions on to MLP. Higher Pb(II) removal revealed the practical applicability of MLP in water and wastewater treatment systems.
Zhao, C., Xie, H., Mu, Y., Xu, X., Zhang, J., Liu, C., Liang, S., Ngo, H.H., Guo, W., Xu, J. & Wang, Q. 2014, 'Bioremediation of endosulfan in laboratory-scale constructed wetlands: effect of bioaugmentation and biostimulation.', Environmental science and pollution research international, vol. 21, no. 22, pp. 12827-12835.
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Bioremediation is widely used in organic pollutants disposal. However, very little has been known on its application in constructed wetlands contaminated with organochlorine pesticide, endosulfan in particular. To evaluate the effect of bioremediation on endosulfan removal and clarify the fate, bioaugmentation and biostimulation were studied in laboratory-scale vertical-flow constructed wetlands. After 20 days' experiment, endosulfan isomers removal efficiencies were increased to 89.24-97.62 % through bioremediation. In bacteria bioaugmentation (E-in) and sucrose biostimulation (E-C), peak concentrations of endosulfan in sediment were reduced by 31.02-76.77 %, and plant absorption were 347.45-576.65 g kg(-1). By contrast, plant absorption in KH2PO4 biostimulation (E-P) was increased to 811.64 and 1,067.68 g kg(-1). Degradation process was probably promoted in E-in and E-C, while plant absorption was enhanced in E-P. Consequently, E-in and E-C were effective for endosulfan removal in constructed wetlands, while adding KH2PO4 had potential to cause air pollution. Additionally, combined bioremediation was not recommended.
Kong, J., Yue, Q., Gao, B., Li, Q., Wang, Y., Ngo, H.H. & Guo, W. 2014, 'Porous structure and adsorptive properties of hide waste activated carbons prepared via potassium silicate activation', Journal of Analytical and Applied Pyrolysis, vol. 109, pp. 311-314.
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Bioremediation is widely used in organic pollutants disposal. However, very little has been known on its application in constructed wetlands contaminated with organochlorine pesticide, endosulfan in particular. To evaluate the effect of bioremediation on endosulfan removal and clarify the fate, bioaugmentation and biostimulation were studied in laboratory-scale vertical-flow constructed wetlands. After 20 days' experiment, endosulfan isomers removal efficiencies were increased to 89.24&#8211;97.62 % through bioremediation. In bacteria bioaugmentation (E-in) and sucrose biostimulation (E-C), peak concentrations of endosulfan in sediment were reduced by 31.02&#8211;76.77 %, and plant absorption were 347.45&#8211;576.65 g kg1. By contrast, plant absorption in KH2PO4 biostimulation (E-P) was increased to 811.64 and 1,067.68 g kg1. Degradation process was probably promoted in E-in and E-C, while plant absorption was enhanced in EP. Consequently, E-in and E-C were effective for endosulfan removal in constructed wetlands, while adding KH2PO4 had potential to cause air pollution. Additionally, combined bioremediation was not recommended.
Wang, J., Yang, J., Zhang, H., Guo, W. & Ngo, H.-.H. 2014, 'Feasibility study on magnetic enhanced flocculation for mitigating membrane fouling', Journal of Industrial and Engineering Chemistry, vol. 26, pp. 37-45.
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During coagulation/flocculation-membrane filtration (CF-MF) process, membrane fouling was alleviated more significantly through magnetic enhanced flocculation-membrane filtration (MEF-MF) in the presence of ferromagnetic seeds in coagulants. Porous cake layer with flocs of large size was able to alleviate decline rate of membrane flux. Foulant analysis proved that magnetic enhanced flocculation (MEF) pretreatment was more efficient for the reductions of low and mid-molecular weight (MW) organic structures than CF-MF. Biopolymers with high molecular weight were also effectively removed before filtration. Overall, MEF-MF could provide a novel alternative approach to mitigate membrane fouling for surface water treatment.
Deng, L., Guo, W., Ngo, H.H., Zhang, J., Liang, S., Xia, S., Zhang, Z. & Li, J. 2014, 'A comparison study on membrane fouling in a sponge-submerged membrane bioreactor and a conventional membrane bioreactor', Bioresource Technology, vol. 165, no. C, pp. 69-74.
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Listowski, A., Ngo, H. & Guo, W. 2013, 'Establishment of an economic evaluation model for urban recycled water', Resources, Conservation and Recycling, vol. 72, pp. 67-75.
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This study aimed at establishing an economic evaluation model to encourage continuing improvement in performance analysis and applying for any infrastructure system of urban recycled water. A thorough study towards characterization and economic performance assessment of urban water reuse scheme were carried out. An integrated evaluation technique was developed by synthesizing the quantitative and qualitative performance indicators related to the water recycled technology and urban water cycle system. Specific performance indicators and indexes were aggregated into an economic analytical modelling for effective evaluation of the water reuse scheme and technology using uniform economic performance standards. Detailed economic analyses were successfully applied to enable determination of economic lifetime of the technology and the whole water reuse scheme. This research confirmed that productivity, efficiency and reliability measurements and factors could be successfully deployed for determining the scheme performance during various life cycle stages (e.g. design development, operational and functional verification, or comparison with other reuse projects). The economic assessment model was applied to improve uniformity of analytical process and performance measure. This article demonstrates benefits associated with the application of a standardized methodology for performing economic assessment and by maintaining strong correlation between multi-parameter approach and adopted performance criteria in terms of productivity, efficiency and reliability. However, to ensure effectiveness of this assessment, the process would require systematic and perpetual inventory of the scheme performance data, consideration of variable factors such as capital and recurrent costs.
Guadie, A., Xia, S., Zhang, Z., Guo, W., Ngo, H. & Hermanowicz, S.W. 2013, 'Simultaneous removal of phosphorus and nitrogen from sewage using a novel combo system of fluidized bed reactor-membrane bioreactor (FBR-MBR)', Bioresource Technology, vol. 149, no. 1, pp. 276-285.
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A FBRMBR combo system was designed as a novel approach for simultaneous phosphorus and nitrogen removal from sewage. The combo system was evaluated more than 7 months under variable pH (7.5-9.5), hydraulic retention times (HRT = 2-10 h), intermittent aeration cycles (IAC) (on/off = 60/60-15/45 min) and sludge retention times (SRT = 1060 d). Prior recovery of phosphorus as struvite in the FBR enhanced nitrogen and COD removal efficiency in MBR. Under optimum operating conditions (pH = 9, HRT = 6 h and IAC = 45/15 min), PO43-P, NH4-N and COD removal efficiencies were 92.6 &plusmn; 4.2, 98.7 &plusmn; 1.2 and 99.3 &plusmn; 0.5%, respectively. Stable mixed liquor suspended solid concentration (3.0-5.0 g/L); enhanced nitrificationdenitrification activity (78-92%) and reduced transmembrane pressure were also achieved. Compared to soluble microbial products, extracellular polymeric substances (EPS) showed strong correlation with fast membrane fouling. Among EPS components, carbohydrate rather than protein was associated with membrane fouling. Except HRT, all parameters considered (pH, IAC, SRT) showed a significant effect on removal efficiency.
Nguyen, L.N., Hai, F., Kang, J., Nghiem, L.D., Price, W.E., Guo, W., Ngo, H. & Tung, K. 2013, 'Comparison between sequential and simultaneous application of activated carbon with membrane bioreactor for trace organic contaminant removal', Bioresource Technology, vol. 130, pp. 412-417.
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The removal efficiency of 22 selected trace organic contaminants by sequential application of granular activated carbon (GAC) and simultaneous application of powdered activated carbon (PAC) with membrane bioreactor (MBR) was compared in this study. Both sequential application of GAC following MBR treatment (MBR&acirc;GAC) and simultaneous application of PAC within MBR (PAC&acirc;MBR) achieved improved removal (over 95%) of seven hydrophilic and biologically persistent compounds, which were less efficiently removed by MBR-only treatment (negligible to 70%). However, gradual breakthrough of these compounds occurred over an extended operation period. Charged compounds, particularly, fenoprop and diclofenac, demonstrated the fastest breakthrough (complete and 50&acirc;70%, in MBR&acirc;GAC and PAC&acirc;MBR, respectively). Based on a simple comparison from the long-term performance stability and activated carbon usage points of view, PAC&acirc;MBR appears to be a better option than MBR&acirc;GAC treatment.
Li, C., liang, S., Zhang, J., Ngo, H., Guo, W., zheng, N. & zou, Y. 2013, 'N2O reduction during municipal wastewater treatment using a two-sludge SBR system acclimatized with propionate', Chemical Engineering Journal, vol. 222, pp. 353-360.
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A two-sludge denitrifying phosphorus removal process (A2N-SBR), acclimatized with propionate, was proposed as an efficient method for nitrous oxide (N2O) reduction during municipal wastewater treatment. Compared with the conventional nitrification&acirc;denitrification process (AO-SBR) operated in parallel, the A2N-SBR not only significantly improved total nitrogen and soluble phosphorus removal efficiencies by around 32.3% and 23.5%, respectively, but also greatly reduced N2O generation by around 31.5%. Moreover, like the anoxic stage of AO-SBR, nearly zero N2O (merely 0.054% of the removed nitrogen) was generated during the anoxic stage of A2N-SBR. The substantial N2O reduction achieved in the proposed A2N-SBR can be reasonably explained by: (i) the use of independent nitrification reactor resulting in higher activity of nitrifying bacteria and no occurrence of heterotrophic denitrification in aerobic stage, and (ii) the use of propionate as carbon source decreasing nitrite accumulation in anoxic stage.
Chen, Z., Ngo, H., Guo, W., Wang, X.C., Miechel, C., Corby, N., Listowski, A. & O'Halloran, K. 2013, 'Analysis of social attitude to the new end use of recycled water for household laundry in Australia by the regression models', Journal of Environmental Management, vol. 126, no. 1, pp. 79-84.
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Recycled water for household laundry can be regarded as a promising strategy to alleviate the current demand on scarce water supplies. Public acceptability becomes fairly important to ensure the successful establishment and development of this new end use. To address the issue, this study conducted social surveys in two locations of Australia, Port Macquarie and Melbourne, where respondents were asked 17 questions. The regression models provide conclusions about which characteristics are more likely to lead to the acceptance of recycled water from society. Three attitudinal variables (RWAlterDW, Attitude and Cost) and three psychological variables (Odour, Reading and SmallUnit) were found to be the key driving forces behind domestic water reuse behaviour. These findings could drive the future research direction to achieve better public perception of this new end use of recycled water.
Wijekoon, K.C., Hai, F.I., Kang, J., Price, W.E., Guo, W., Ngo, H. & Nghiem, L.D. 2013, 'The fate of pharmaceuticals, steroid hormones, phytoestrogens, UV-filters and pesticides during MBR treatment', Bioresource Technology, vol. 144, pp. 247-254.
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This study examined the relationship between molecular properties and the fate of trace organic contaminants (TrOCs) in the aqueous and solid phases during wastewater treatment by MBR. A set of 29 TrOCs was selected to represent pharmaceuticals, steroid hormones, phytoestrogens, UV-filters and pesticides that occur ubiquitously in municipal wastewater. Both adsorption and biodegradation/transformation were found responsible for the removal of TrOCs by MBR treatment. A connection between biodegradation and molecular structure could be observed while adsorption was the dominant removal mechanism for the hydrophobic (logD > 3.2) compounds. Highly hydrophobic (logD > 3.2) but readily biodegradable compounds did not accumulate in sludge. In contrast, recalcitrant compounds with a moderate hydrophobicity, such as carbamazepine, accumulated significantly in the solid phase. The results provide a framework to predict the removal and fate of TrOCs by MBR treatment.
Li, J., Li, J., Wang, H., Cheng, B., He, B., Yan, F., Yang, Y., Guo, W. & Ngo, H. 2013, 'Electrocatalytic oxidation of n-propanol to produce propionic acid using an electrocatalytic membrane reactor', Chemical communications Chemcomm, vol. 49, pp. 4501-4503.
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An electrocatalytic membrane reactor assembled using a nano-MnO2 loading microporous Ti membrane as an anode and a tubular stainless steel as a cathode was used to oxidize n-propanol to produce propionic acid. The high efficiency and selectivity obtained is related to the synergistic effect between the reaction and separation in the reactor.
Fan, J., Zhang, B., Zhang, J., Ngo, H., Guo, W., Liu, F., Guo, Y. & Wu, H. 2013, 'Intermittent aeration strategy to enhance organics and nitrogen removal in subsurface flow constructed wetlands', Bioresource Technology, vol. 141, no. 1, pp. 117-122.
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In this study, an intermittent-aerated subsurface flow constructed wetland (SFCW) A was set up to assess its performance in decentralized rural sewage treatment. A conventional SFCW B and a subsurface wastewater infiltration system (SWIS C) were also constructed for comparison. Alternate anaerobic and aerobic conditions were well developed by intermittent aeration. High removal of organic pollutants (29.3 g m-2 d-1), ammonium nitrogen (3.5 g m-2 d-1) and total nitrogen (3.3 g m-2 d-1) were obtained simultaneously in SFCW A compared with SFCW B and SWIS C. Fluorescence in situ hybridization analysis proved that the intermittent aeration obviously enhanced the growth of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in SFCW A. These results suggest that intermittent aeration strategy is reliable to enhance the performance of SFCWs in decentralized rural sewage treatment.
Zuthi, M., Ngo, H., Guo, W., Li, J., Xia, S. & Zhang, Z. 2013, 'New proposed conceptual mathematical models for biomass viability and membrane fouling of membrane bioreactor', Bioresource Technology, vol. 142, no. 1, pp. 737-740.
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The production and accumulation of soluble microbial products (SMP), extracellular polymeric substances (EPS) and colloidal inert compounds within a membrane bioreactor (MBR) may greatly affect the biomass viability and subsequently the permeability of the membrane. This paper aims at presenting new mathematical models of biomass viability and membrane fouling that has been conceptually developed through establishing links between these biomass parameters and operating parameters of the MBR. The proposed models can be used to predict the biomass viability and membrane fouling at any state of operation of MBR. Meanwhile, easily measurable parameters of the proposed model can also serve to estimate SMP/EPS concentration in the supernatant of MBR without the tedious and expensive measurement.
Li, C., Wang, T., Zheng, N., Zhang, J., Ngo, H., Guo, W. & Liang, S. 2013, 'Influence of organic shock loads on the production of N2O in denitrifying phosphorus removal process', Bioresource Technology, vol. 141, no. 1, pp. 160-166.
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In this work, the influences of short-term organic shock loads on N2O production during denitrifying phosphorus removal were investigated by changing the influent COD concentrations (100, 200, 350, and 500 mg/L). After switching the COD concentrations from 200 to 350 or 500 mg/L, N2O-N production amount increased from 1.62% to 7.12% or 3.29% of the TN removal, respectively, while the corresponding effluent phosphorus concentrations increased from 1.84 to 16.55 and 56.08 mg/L, respectively, which were higher than the influent phosphorus concentration (4.93 mg/L). Furthermore, when the COD concentration was decreased to 100 mg/L, N2O-N production amount was only 1.20%. All results suggested that higher organic shock loads increased N2O production. The main reason was that higher organic shock loads increased anaerobic poly-b-hydroxyalkanoates (PHA) synthesis, which resulted in higher nitrite accumulation. The influences of higher organic shock loads on N2O production could be minimized by adopting continuous nitrate addition strategy.
Fan, J., Wang, W., Zhang, B., Guo, Y., Ngo, H., Guo, W., Zhang, J. & Wu, H. 2013, 'Nitrogen removal in intermittently aerated vertical flow constructed wetlands: Impact of influent COD/N ratios', Bioresource Technology, vol. 143, no. 1, pp. 461-466.
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The performance response of eight vertical flow constructed wetlands (VFCWs) to different influent COD/N ratios and intermittent aeration in domestic wastewater treatment was investigated. Almost complete nitrification was obtained by intermittent aeration, which well developed alternate anaerobic and aerobic conditions for nitrification and denitrification. Sufficient carbon source supply resulted from influent COD/N ratio of 10 simultaneously obtained high removals of COD (96%), ammonia nitrogen (99%) and total nitrogen (90%) in intermittently aerated VFCWs. In all non-aerated VFCWs, poor nitrification was observed due to oxygen deficiency whilst high COD/N ratios further led to lower COD and nitrogen removal efficiency. The results suggest that intermittent aeration combined with high influent COD/N ratios could achieve high nitrogen removal in VFCWs.
Nguyen, T., Ngo, H., Guo, W., Zhang, J., Liang, S., Yue, Q., Li, Q. & Nguyen, V. 2013, 'Applicability of agricultural waste and by-products for adsorptive removal of heavy metals from wastewater', Bioresource Technology, vol. 148, no. 1, pp. 574-585.
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This critical review discusses the potential use of agricultural waste based biosorbents (AWBs) for sequestering heavy metals in terms of their adsorption capacities, binding mechanisms, operating factors and pretreatment methods. The literature survey indicates that AWBs have shown equal or even greater adsorption capacities compared to conventional adsorbents. Thanks to modern molecular biotechnologies, the roles of functional groups in biosorption process are better understood. Of process factors, pH appears to be the most influential. In most cases, chemical pretreatments bring about an obvious improvement in metal uptake capacity. However, there are still several gaps, which require further investigation, such as (i) searching for novel, multi-function AWBs, (ii) developing cost-effective modification methods and (iii) assessing AWBs under multi-metal and real wastewater systems. Once these challenges are settled, the replacement of traditional adsorbents by AWBs in decontaminating heavy metals from wastewater can be expected in the future.
Zuthi, M., Ngo, H., Guo, W., Zhang, J. & Liang, S. 2013, 'A review towards finding a simplified approach for modelling the kinetics of the soluble microbial products (SMP) in an integrated mathematical model of membrane bioreactor (MBR)', International Biodeterioration & Biodegradation, vol. 85, no. 1, pp. 466-473.
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Soluble microbial products (SMPs) tend to accumulate in the membrane bioreactor (MBR) systems as a consequence of high membrane rejection and apparently low biodegradability within the wastewater treatment system. The extension of the activated sludge models (ASMs) with SMPs, therefore, has received crucial importance in recent days, particularly considering their potential use as indicators of the membrane fouling propensity. This paper presents a critical review of the formation and degradation kinetics of SMP subdivisions that have so far been used for the mathematical modelling of MBR. The paper identified a simplified approach to incorporate the kinetics of the SMP formation and degradation in the general mathematical models of MBR. It suggested that the inclusion of only four additional linear differential equations in the ASM1-SMP integrated mathematical model could simulate well the effluent quality and membrane fouling prediction. The model would also serve as a useful tool in optimizing operation conditions for better treatability and fouling control.
Kong, Q., Zhang, J., Ngo, H., Ni, S., Fu, R., Guo, W., Guo, N. & Tian, L. 2013, 'Nitrous oxide emission in an aerobic granulation sequencing batch airlift reactor at ambient temperatures', International Biodeterioration & Biodegradation, vol. 85, no. 1, pp. 533-538.
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This study aims to investigate the nitrous oxide (N2O) emission in an aerobic granulation sequencing batch airlift reactor (SBAR) and the associated microbial community of aerobic granular sludge at ambient temperature (18+-3)0C. After 48 days of operation, 1-2 mm granules were obtained and excellent chemical oxygen demand (COD) and ammonium NH4-N removal efficiencies were stably achieved. N2O concentration in the off gas was maximal at the beginning of the aerobic period and stabilized at a lower concentration after an initial peak. (0.60+-0.17, n=3) % of the total nitrogen load to the SBAR was emitted as N2O. A dramatic change in the microbial community structure was noted between the initial seed sludge and the final mature aerobic granular sludge. Nitrosospira was identified to be the dominant ammonium oxidizing bacteria (AOB) which was attributed as the dominant source of N2O production in aerobic granular sludge by analysis of 16S rDNA sequences.
Nguyen, T., Ngo, H., Guo, W., Zhang, J., Liang, S. & Tung, K. 2013, 'Feasibility of iron loaded 'okara' for biosorption of phosphorous in aqueous solutions', Bioresource Technology, vol. 150, no. 1, pp. 42-49.
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This study investigated the feasibility of using soybean milk by-products (okara) as a sustainable biosorbent for phosphate removal in water and wastewater. The results show that raw okara could hardly decontaminate phosphate from aqueous solutions. Hence, in this work, okara was modified by being cationized using FeCl3 0.25 M (namely iron loaded okara, ILO) to enhance the phosphorus adsorption capacity. The phosphate sorption onto ILO was well achieved under the conditions of pH 3, initial phosphorous concentration of 25 mg/L, biosorbent dose of 20 mg/L and contact time of 7 h. Based on Langmuir model, the maximum adsorption capacity of phosphate by ILO was 4.785 mg/g. The effects of interfering anions were in the order of CO3 > SO4 > NO3 . It was also observed that Fe(III) was detached during operation. This problem can hinder the sustainable usability of ILO. Thus, further research would be necessary for improving the modification method.
Mainali, B., Pham, N., Ngo, H. & Guo, W. 2013, 'Maximum allowable values of the heavy metals in recycled water for household laundry', Science of the Total Environment, vol. 452-453, no. 1, pp. 427-432.
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Household laundry as a new end use of recycled water in dual reticulation systems has a great potential as the significant amount of potablewater fromurban households can be saved. However, there is still no sufficient evidence and supporting recycledwater quality guidelines for this particular use. A key gap in knowledge is the impact of heavymetals in recycledwater on clothes and washingmachines. Thus, this study aims to determine the maximumallowable values (MAVs) of the heavy metals iron (Fe), lead (Pb), zinc (Zn), copper (Cu), andmanganese (Mn) in recycled water for washing clothes in washing machines. Six different concentrations of each targeted metals were prepared in tap water for the washing machine experiments. The tearing/tensile strength tests were used for the assessment of cloth durability.MINITAB 16 as a statistical tool was used and ANOVA one way testwas applied for the significance analysis (Turkey's test p b 0.05). The results show that theMAVs of the heavy metals Fe, Pb, Zn, Cu and Mn were found to be 1 mg/l, 1 mg/l, 10 mg/l, 5 mg/l and 1 mg/l respectively in terms of cloth durability.
Jia, W., liang, S., Zhang, J., Ngo, H., Guo, W., Yan, Y. & zou, Y. 2013, 'Nitrous oxide emission in low-oxygen simultaneous nitrification and denitrification process: Sources and mechanisms', Bioresource Technology, vol. 136, no. 1, pp. 444-451.
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This study attempts to elucidate the emission sources and mechanisms of nitrous oxide (N2O) during simultaneous nitrification and denitrification (SND) process under oxygen-limiting condition. The results indicated that N2O emitted during low-oxygen SND process was 0.8 &plusmn; 0.1 mg N/gMLSS, accounting for 7.7% of the nitrogen input. This was much higher than the reported results from conventional nitrification and denitrification processes. Batch experiments revealed that nitrifier denitrification was attributed as the dominant source of N2O production. This could be well explained by the change of ammonia-oxidizing bacteria (AOB) community caused by the low-oxygen condition. It was observed that during the lowoxygen SND process, AOB species capable of denitrification, i.e., Nitrosomonas europaea and Nitrosomonas-like, were enriched whilst the composition of denitrifiers was only slightly affected. N2O emission by heterotrophic denitrification was considered to be limited by the presence of oxygen and unavailability of carbon source.
Nguyen, T.T., Ngo, H. & Guo, W. 2013, 'Effect of sponge volume fraction on the performance of a novel fluidized bed bioreactor', Water Science and Technology, vol. 67, no. 11, pp. 2645-2650.
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A novel fluidized bed bioreactor (FBBR) was designed by integration of anaerobic granular activated carbon and aerobic sponge reactors. This FBBR was evaluated at different sponge volume fractions for treating a synthetic wastewater. Polyester urethane sponge with cube size of 1 1 1 cm and density of 2830 kg/m3 with 90 cells per 25 mm was used as biomass carrier. The results indicate that the FBBR could remove more than 93% of dissolved organic carbon (DOC). The highest nutrient removal efficiencies (58.2% PO4-P and 75.4% NH4-N) were achieved at 40% sponge volume fraction. The system could provide a good condition for biomass growth (e.g. 186.2 mg biomass/g sponge). No significant different performance in specific oxygen uptake rate was observed between 30, 40, and 50% sponge volume fractions.
Zuthi, M., Ngo, H., Guo, W. & Nguyen, T.T. 2013, 'The effects of biomass parameters on the dissolved organic carbon removal in a sponge submerged membrane bioreactor', World Academy of Science, Engineering and Technology, vol. 78, no. 1, pp. 46-50.
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A novel sponge submerged membrane bioreactor (SSMBR) was developed to effectively remove organics and nutrients from wastewater. Sponge is introduced within the SSMBR as a medium for the attached growth of biomass. This paper evaluates the effects of new and acclimatized sponges for dissolved organic carbon (DOC) removal from wastewater at different mixed liquor suspended solids (MLSS) concentration of the sludge. It was observed in a series of experimental studies that the acclimatized sponge performed better than the new sponge whilst the optimum DOC removal could be achieved at 10g/L of MLSS with the acclimatized sponge. Moreover, the paper analyses the relationships between the MLSSsponge/MLSSsludge and the DOC removal efficiency of SSMBR. The results showed a non-linear relationship between the biomass parameters of the sponge and the sludge, and the DOC removal efficiency of SSMBR. A second-order polynomial function could reasonably represent these relationships.
Chen, Z., Ngo, H., Guo, W. & Wang, X. 2013, 'Analysis of Sydney's recycled water schemes', Frontiers of Environmental Science and Engineering, vol. 7, no. 4, pp. 608-615.
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Recycled water provides a viable opportunity to partially supplement fresh water supplies as well as substantially alleviate environmental loads. Currently, thousands of recycled water schemes have been successfully conducted in a number of countries and Sydney is one of the leading cities, which has made massive effort to apply water reclamation, recycling and reuse. This study aims to make a comprehensive analysis of recycled water schemes in Sydney for a wide range of end uses such as landscape irrigation, industrial process uses and residential uses (e.g., golf course irrigation, industrial cooling water reuse, toilet flushing and clothes washing etc.). For each representative recycled water scheme, this study investigates the involved wastewater treatment technologies, the effluent quality compared with specified guideline values and public attitudes toward different end uses. Based on these obtained data, multi criteria analysis (MCA) in terms of risk, cost-benefit, environmental and social aspects can be performed. Consequently, from the analytical results, the good prospects of further expansion and exploration of current and new end uses were identified toward the integrated water planning and management. The analyses could also help decision makers in making a sound judgment for future recycled water projects.
Zuthi, M., Guo, W., Ngo, H., Nghiem, L.D. & Hai, F.I. 2013, 'Enhanced biological phosphorus removal and its modeling for the activated sludge and membrane bioreactor processes', Bioresource Technology, vol. 139, no. 1, pp. 363-374.
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A modified activated sludge process (ASP) for enhanced biological phosphorus removal (EBPR) needs to sustain stable performance for wastewater treatment to avoid eutrophication in the aquatic environment. Unfortunately, the overall efficiency of the EBPR in ASPs and membrane bioreactors (MBRs) is frequently hindered by different operational/system constraints. Moreover, although phosphorus removal data from several wastewater treatment systems are available, a comprehensive mathematical model of the process is still lacking. This paper presents a critical review that highlights the core issues of the biological phosphorus removal in ASPs and MBRs while discussing the inhibitory process requirements for other nutrients removal. This mini review also successfully provided an assessment of the available models for predicting phosphorus removal in both ASP and MBR systems. The advantages and limitations of the existing models were discussed together with the inclusion of few guidelines for their improvement.
Jia, W., Liang, S., Ngo, H., Guo, W., Zhang, J., Wang, R. & Zou, Y. 2013, 'Effect of phosphorus load on nutrients removal and N2O emission during low-oxygen simultaneous nitrification and denitrification process', Bioresource Technology, vol. 141, no. 1, pp. 123-130.
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Three laboratory scale anaerobicaerobic (low-oxygen) SBRs (R1, R2 and R3) were conducted at different influent phosphorus concentration to evaluate the impacts of phosphorus load on nutrients removal and nitrous oxide (N2O) emission during low-oxygen simultaneous nitrification and denitrification (SND) process. The results showed that TP and TN removals were enhanced simultaneously with the increase in phosphorus load. It was mainly caused by the enrichment of polyphosphate accumulating organisms (PAOs) under high phosphorus load and low COD/P ratio (<50), which could use nitrate/nitrite as electron acceptors to take up the phosphorus. N2O emission was reduced with increasing phosphorus load. N2O-N emission amount per cycle of R3 was 24.1% lower than that of R1. It was due to the decrease of N2O yield by heterotrophic denitrification. When the phosphorus load increased from R1 to R3, heterotrophic denitrification (D) ranged from 42.6% to 36.6% of the N2O yield.
Nguyen, T.T., Ngo, H. & Guo, W. 2013, 'Pilot scale study on a new membrane bioreactor hybrid system in municipal wastewater treatment', Bioresource Technology, vol. 141, pp. 8-12.
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A pilot scale membrane bioreactor hybrid system (MBR-HS) was evaluated for municipal wastewater treatment. This novel system comprised of a granular activated carbon-sponge fluidized bed bioreactor (GACS-FBBR) followed by a submerge membrane bioreactor (MBR) with the capacity of 2 L/min. The results indicated that the MBR-HS could effectively remove 90% DOC and 95% NH4N. PO4P removal efficiency was remained stable at about 70% throughout the experiment. Specific oxygen uptake rate (SOUR) of activated sludge increased from 0.72 to 2.21 mg O2/gVSS h for the first 10 days and then followed by a steady stage until the end of experiment. Sludge volume index (SVI) was always below 50 mL/g, demonstrated an excellent settling properties of sludge. The system also showed an achievement in terms of low trans-membrane pressure (TMP) development rate. The TMP increasing rate was only 0.65 kPa/day, suggesting GACS-FBBR can be a promising pre-treatment for MBR.
Mainali, B., Pham, N., Ngo, H., Guo, W., Miechel, C., O'Halloran, K., Muthukaruppan, M. & Listowski, A. 2013, 'Vision and perception of community on the use of recycled water for household laundry: A case study in Australia', Science of the Total Environment, vol. 463-464, no. 1, pp. 657-666.
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This study investigates the community perception of household laundry as a new end use of recycled water in three different locations of Australia through a face to face questionnaire survey (n = 478). The study areas were selected based on three categories of (1) non-user, (2) perspective user and (3) current user of recycled water. The survey results indicate that significantly higher number (70%) of the respondents supported the use of recycled water for washing machines (?2 = 527.40, df = 3; p = 0.000). Significant positive correlation between the overall support for the new end use and the willingness of the respondents to use recycled water for washing machine was observed among all users groups (r = 0.43, p = 0.000). However, they had major concerns regarding the effects of recycled water on the aesthetic appearance of cloth, cloth durability, machine durability, odour of the recycled water and cost along with the health issues. The perspective user group had comparatively more reservations and concerns about the effects of recycled water on washing machines than the non-users and the current users (?2 = 52.73, df = 6; p = 0.000). Overall, community from all three study areas are willing towelcome this new end use as long as all their major concerns are addressed and safety is assured.
Li, C., Zhang, J., Liang, S., Ngo, H., Guo, W., Zhang, Y. & Zou, Y. 2013, 'Nitrous oxide generation in denitrifying phosphorus removal process: Main causes and control measures', Environmental Science and Pollution Research, vol. 20, pp. 5353-5360.
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Despite the many benefits of denitrifying phosphorus removal process, the significant generation of nitrous oxide (N2O), a potent greenhouse gas, remains a problem for this innovative and promising process. To better understand and more effectively control N2O generation in denitrifying phosphorus removal process, batch experiments were carried out to investigate the main causes of N2O generation, based on which the control measures were subsequently proposed. The results showed that N2O generation accounted for 0.41 % of the total nitrogen removal in denitrifying phosphorus removal process, whereas, in contrast, almost no N2O was generated in conventional denitrification process. It was further demonstrated that the weak competition of N2O reductase for electrons and the high nitrite accumulation were the two main causes for N2O generation, evidenced by N2O production and reduction rates under different conditions. Accordingly, the reduction of N2O generation was successfully achieved via two control measures: (1) the use of continuous nitrate addition reducing N2O generation by around 91.4 % and (2) the use of propionate as the carbon source reducing N2O generation by around 69.8 %.
Ma, X., Wang, X.C., Ngo, H., Guo, W., Wu, M.N. & Wang, N. 2013, 'Reverse osmosis pretreatment method for toxicity assessment of domestic wastewater using Vibrio qinghaiensis sp.-Q67', Ecotoxicology And Environmental Safety, vol. 97, no. 1, pp. 248-254.
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Luminescent bacterial test is a fast and sensitive method for acute toxicity assessment of water and wastewater. In this study, an improved toxicity testing method was developed using the freshwater luminescent bacteria Vibrio qinghaiensis sp.-Q67 that involved pretreatment of water samples with reverse osmosis (RO) to eliminate the interferences caused by nutrients in concentrated samples and to improve the reliability and sensitivity of the analysis. Because water samples contain low concentrations of several target toxic substances, rapid acute toxicity testing method that is commonly employed does not achieve enough sensitivity. The proposed RO pretreatment could effectively enrich organic and inorganic substances in water samples to enable a more effective and sensitive toxicity evaluation. The kinetic characteristics of toxicity of raw sewage and secondary effluent were evaluated based on the relative luminescence unit (RLU) curves and timeconcentration-effect surfaces. It was observed that when the exposure time was prolonged to 8-h or longer, the bacteria reached the logarithmic growth stage. Hence, the stimulating effects of the coexisting ions (such as Na+, K+, NO3-) in the concentrated samples could be well eliminated. A 10-h exposure time in proposed Q67 test was found to quantitatively evaluate the toxicity of the organic and inorganic pollutants in the RO-concentrated samples.
Chen, Z., Ngo, H. & Guo, W. 2013, 'A Critical Review on the End Uses of Recycled Water', Critical Reviews in Environmental Science and Technology, vol. 43, no. 14, pp. 1446-1516.
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Recycled water provides a viable opportunity to supplement water supplies as well as alleviate environmental loads. The authors examine the sources of recycled water and discusses various end uses. They focus on reviewing the historical development and current status of recycled water on a global scale with containing the evolvement of wastewater treatment technologies, water quality guidelines, and public attitudes. The authors also illustrate typical case studies of recycled water in a number of countries and regions, including Australia, Asia, the United States, Latin America, Europe, the Middle East, and Africa. These pilot studies can be good examples for the future projects. They identify the good prospects of further expansion and exploration of current and new end uses while emphasizing the integrated water planning and management as well as challenging and tasks in the future.
Chen, Z., Ngo, H. & Guo, W. 2013, 'Risk control in recycled water schemes', Critical Reviews in Environmental Science and Technology, vol. 43, no. 22, pp. 2439-2510.
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Recycled water is becoming one of the indispensable and reliable water resources at present. When it is introduced as an alternative source, risks on human health and the environment become major constraints driving the application and extension of recycled water. The authors examine the sources and associated risks of recycled water and introduce the practical risk control technologies on various end uses. They also review some existing risk assessment models by comparing their strengths and weaknesses toward the good approach of integrated modeling. Some critical suggestions on risk management and communication are made based on the given information.
Hossain, M.D., Ngo, H. & Guo, W. 2013, 'Introductory of Microsoft Excel SOLVER function-Spreadsheet method for isotherm and kinetics modelling of metals biosorption in water and wastewater', Journal of Water Sustainability, vol. 3, no. 4, pp. 223-237.
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This paper aims to introduce a simple method to run a complicated non-linear analysis of isotherm and kinetics models for metals biosorption based on input functions of spreadsheets. A robust method is demonstrated here to exploit the `SOLVER function available in Microsoft (MS) Excel spreadsheet. It is more economic and user friendly than specialized computer programmes. In this study, an iterative method was proposed to produce the optimal goodness of fit between experimental data and predicted data. This was described the implementing method of a set of real data (garden grass as biosorbent) and the predicted results were compared with linear analysis and MATLAB analysis. The R2 values found from MS Excel spreadsheet were 0.995, 0.999 and 0.996 while being 0.997, 1.000 and 0.999 by MATLAB for copper, lead and cadmium adsorption, respectively onto garden grass. The prediction of maximum adsorption, qm by excel (59.336, 63.663 and 42.310 mg/g) were very similar to MATLAB (59.889, 63.509 and 41.560 mg/g). The predictions of kinetics parameters were also close to MATLAB analysis. Hence, the MS Excel Spreadsheet method could be a handy tool for biosorption models.
Hossain, M., Ngo, H., Guo, W. & Nguyen, V. 2012, 'Palm Oil Fruit Shells As Biosorbent For Copper Removal From Water And Wastewater: Experiments And Sorption Models', Bioresource Technology, vol. 113, pp. 97-101.
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Palm oil fruit shells were evaluated as a new bioadsorbent to eliminate toxic copper from water and wastewater. Without any chemical treatment, palm oil fruit shells were washed, dried and grounded into powder (<75 lm) for use in the experiments. Characterization showed mesopore based bioadsorbent was prepared from palm oil fruit shells. The results indicate that the highest Cu removal efficiency was found in an aqueous solution with pH of 6.5. The equilibrium sorption capacity of copper was significantly high (between 28 and 60 mg/g) at room temperature. Nonlinear regression analyses for isotherm models revealed that three-parameter isotherms had a better fit to the experimental data (R2 > 0.994) than that of two-parameter isotherms. The copper sorption system was heterogeneous as the values of exponents were lying between 0 and 1. The highly correlated pseudo-second-order kinetics model (R2 > 0.998) ascertained the applicability of copper removal by palm oil fruit shells.
Nguyen, T.T., Ngo, H., Guo, W., Listowski, A. & Li, J.X. 2012, 'Evaluation Of Sponge Tray-Membrane Bioreactor (ST-MBR) For Primary Treated Sewage Effluent Treatment', Bioresource Technology, vol. 113, pp. 143-147.
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The membrane bioreactor system (MBR) with pre-treatment of sponge tray bioreactor (STB) was evaluated at different operating conditions for treating primary treated sewage (PTS). The result indicated the successful removal of DOC with the efficiency of higher than 95%. The highest nutrient removal efficiency of 83.6% (NH4-N) and 75.5% (PO4-P) was observed at sludge concentration of 330 mg/L. Specific oxygen uptake rate (SOUR) of activated sludge in MBR kept increasing up to 6 mg O2/g VSS h during stage IV. The sludge volume index (SVI) of less than 100 mL/g during the operation indicated the good settling property of the sludge. At highest sludge concentration of 5 g/L, trans-membrane pressure (TMP) was increasing dramatically during first 15 d up to 25 kPa; however it was only 6 kPa at lower sludge concentrations. It is concluded that the system showed the highest performance at stage III with sludge concentration of 330 mg/L.
Xing, W., Ngo, H., Guo, W., Listowski, A. & Cullum, P. 2012, 'Optimization Of An Integrated Sponge - Granular Activated Carbon Fluidized Bed Bioreactor As Pretreatment To Microfiltration In Wastewater Reuse', Bioresource Technology, vol. 113, pp. 214-218.
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A specific integrated fluidized bed bioreactor (iFBBR) was optimized in terms of organic loading rate (OLR), hydraulic retention time (HRT) and frequency of new sustainable flocculant (NSBF) addition for primary treated sewage effluent (PTSE) treatment. It was observed that iFBBR achieved the best performance with the operating conditions of 4 times/day NSBF addition, HRT of 90 min and OLR of 8.64 kgCOD/day m3. The removal efficiencies were found to be more than 93% of dissolved organic carbon (DOC), 61% of total nitrogen (T-N) and 60% of total phosphorus (T-P). iFBBR as pretreatment of submerged microfiltration (SMF) is successful in increasing the critical flux and reducing the membrane fouling. NSBF-iFBBR-SMF hybrid system led to very high organic removal efficiency with an average DOC removal of 97% from synthetic PTSE.
Chen, Z., Ngo, H. & Guo, W. 2012, 'A Critical Review On Sustainability Assessment Of Recycled Water Schemes', The Science of the Total Environment, vol. 426, pp. 13-31.
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Recycled water provides a viable opportunity to supplement water supplies as well as alleviate environmental loads. To further expand current schemes and explore new recycled water end uses, this study reviews several environmental assessment tools, incl
Guo, W., Ngo, H. & Li, J. 2012, 'A mini-review on membrane fouling', Bioresource Technology, vol. 122, no. 1, pp. 27-34.
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During the last decades, the interest of using membrane technology has emerged in wastewater treatment as well as drinking water and process water production. However, the impediment of the membrane technology is the fouling problem and consequently higher operating and membrane replacement cost. Hence, better understanding of membrane fouling is not only the key to solve the problems, but also is one of the main factors driving membrane technology forward. This mini-review paper identifies the major foulants and the principal membrane fouling mechanisms such as pore blocking, cake formation, concentration polarization, organic adsorption, inorganic precipitation and biological fouling. It also gives a holistic review about different fouling phenomena during the application of membrane separation technologies in water and wastewater treatment, with specific references to various problems, membranes, treatment processes and its practical applications.
Hossain, A., Ngo, H., Guo, W. & Setiadi, T. 2012, 'Adsorption and desorption of copper(II) ions onto garden grass', Bioresource Technology, vol. 121, pp. 386-395.
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The garden grass (GG) was firstly used to remove copper(II) from water as bioadsorbent. From the results of characterisation, the GG had the merits of high specific surface area, significant adsorption sites and functional groups. Copper-adsorption significantly depends on the initial copper concentrations, contact time, pH, adsorbent doses, particle sizes and temperature. The positive values of DG indicates that the adsorption of copper onto garden grass is non-spontaneous and values lies within the ranges of 4.452&acirc;13.660 kJ/mol for supporting physical adsorption. 0.1 N H2SO4 was found as suitable eluent, which could be used 5 cycles of adsorption&acirc;desorption. The data from adsorption and desorption equilibrium were well fitted by the Langmuir, SIPS and Redlich&acirc;Peterson isotherm models. The maximum adsorption and desorption capacities were 58.34 and 319.03 mg/g, respectively, for 1 g dose. Adsorption and desorption kinetics could be described by the Pseudo-first-order model.
Nguyen, V., Ngo, H., Guo, W., Li, J. & Listowski, A. 2012, 'Effects of Sludge Concentrations and Different Sponge Configurations on the Performance of a Sponge-Submerged Membrane Bioreactor', Applied Biochemistry and Biotechnology, vol. 167, pp. 1678-1687.
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The performance of a novel sponge-submerged membrane bioreactor (SSMBR) was evaluated to treat primary treated sewage effluent at three different activated sludge concentrations. Polyurethane sponge cubes with size of 1&Atilde;1&Atilde;1 cm were used as attached growth media in the bioreactor. The results indicated the successful removal of organic carbon and phosphorous with the efficiency higher than 98% at all conditions. Acclimatised sponge MBR showed about 5% better ammonia nitrogen removal at 5 and 10 g/L sludge concentration as compared to the new sponge system. The respiration test revealed that the specific oxygen uptake rate was around 1.0&acirc;3.5 mgO2/gVSS.h and likely more stable at 10 g/L sludge concentration. The sludge volume index of less than 100 mL/g during the operation indicated the good settling property of the sludge. The low mixed liquor suspended solid increase indicated that SSMBR could control the sludge production. This SSMBR was also successful in reducing membrane fouling with significant lower transmembrane pressure (e.g. only 0.5 kPa/day) compared to the conventional MBR system. Further study will be conducted to optimise other operating conditions.
Liu, C., Ngo, H., Guo, W. & Tung, K. 2012, 'Optimal conditions for preparation of banana peels, sugarcane bagasse and watermelon rind in removing copper from water', Bioresource Technology, vol. 119, pp. 349-354.
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In this study, three agro-waste materials were used as biosorbents for removal of copper (Cu) from water. This work aims to optimise conditions for preparation of these materials to obtain maximum Cu adsorption capacity. The optimal conditions were determined in terms of Cu removal efficiency and/or energy consumption. The results indicate that banana peels dried at 120 C for 2 h and ground into powder form led to a better performance in terms of both copper removal efficiency and energy consumption. For sugarcane bagasse and watermelon rind, 120 C was the suitable drying temperature. However, the best drying time was 1 h for sugarcane bagasse and 3 h for watermelon rind. The powder form with size of <150 lm was optimal for all biosorbents in terms of removal efficiency and equilibration time. The findings are beneficial to the application of these agro-waste materials for Cu removal from water and wastewater treatment.
Zuthi, M., Ngo, H. & Guo, W. 2012, 'Modelling bioprocesses and membrane fouling in membrane bioreactor (MBR): A review towards finding an integrated model framework', Bioresource Technology, vol. 122, pp. 119-129.
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The bioprocesses taking place in activated sludge wastewater treatment system itself are characterized by great complexity and yet incomplete understanding of some of the phenomena involved. The MBR technology inherent deficiencies for its simulation due to additional intrinsic complexities resulting from the interaction between concurrently occurring and dynamic biological processes with membrane filtration and the straightforward adoption of the activated sludge models&acirc; (ASM) frameworks or their modified variations. In this backdrop, this paper compiles a brief overview of the previous developments to the current state-of-the-art mathematical modelling approaches of the MBR system. With extended discussions on particular topics such as applications of modified ASMs to MBR modelling, ASM extensions incorporating soluble microbial products (SMP)/extracellular polymeric substances EPS) concepts, this paper also provides a guide for different end-users of mathematical models of MBR systems.
Chen, Z., Guo, W., Ngo, H., Listowski, A., O'Halloran, K., Thompson, M. & Muthukaruppan, M. 2012, 'Multi-criteria analysis towards the new end use of recycled water for household laundry: A case study in Sydney', The Science of the Total Environment, vol. 438, pp. 59-65.
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This paper aims to put forward several management alternatives regarding the application of recycled water for household laundry in Sydney. Based on different recycled water treatment techniques such as microfiltration (MF), granular activated carbon (GAC) or reverse osmosis (RO), and types of washing machines (WMs), five alternatives were proposed as follows: (1) do nothing scenario; (2) MF+existing WMs; (3) MF+newWMs; (4) MF&acirc;GAC+existing WMs; and (5) MF&acirc;RO+existing WMs. Accordingly, a comprehensive quantitative assessment on the trade-off among a variety of issues (e.g., engineering feasibility, initial cost, energy consumption, supply flexibility and water savings) was performed over the alternatives. This was achieved by a computer-based multi-criteria analysis (MCA) using the rank order weight generation together with preference ranking organization method for enrichment evaluation (PROMETHEE) outranking techniques. Particularly, the generated 10,000 combinations of weights via Monte Carlo simulation were able to significantly reduce the man-made errors of single fixed set of weights because of its objectivity and high efficiency. To illustrate the methodology, a case study on Rouse Hill Development Area (RHDA), Sydney, Australia was carried out afterwards. The study was concluded by highlighting the feasibility of using highly treated recycled water for existing and new washing machines. This could provide a powerful guidance for sustainable water reuse management in the long term. However, more detailed field trials and investigations are still needed to effectively understand, predict and manage the impact of selected recycled water for new end use alternatives.
Liu, C., Ngo, H. & Guo, W. 2012, 'Watermelon Rind: Agro-waste or Superior Biosorbent?', Applied Biochemistry and Biotechnology, vol. 167, no. 6, pp. 1699-1715.
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Biosorption of copper (Cu), zinc (Zn), and lead (Pb) on watermelon rind in a wellstirred batch system was investigated. pH showed significant influence on the biosorption process. Optimal pH for Cu, Zn, and Pb biosorption was found to be 5.0, 6.8 and 6.8, respectively. Watermelon rind was in favor of Pb and it could remove up to 99% Pb between pH ranges of 5 and 6.8 when Pb concentration is lower than 100 mg/L. The biosorptive capacity of watermelon on Cu, Zn, and Pb was 6.281, 6.845, and 98.063 mg/g, respectively. The equilibrium data fitted well to Langmuir adsorption isotherm while pseudo-secondorder kinetic model exhibited more advantages for describing kinetic data than pseudo-firstorder kinetic model. NaOH was found to be a suitable eluent. After desorption in NaOH solution, the resorption efficiency reached as high as 99% of these three metals either in a single-component or multi-component system. From the characterization study, ion exchange and micro-precipitation were estimated to be the main mechanisms. Due to its high metal uptake capacity, reusability, and metal recovery, watermelon rind can be considered as an eco-friendly and economic biosorbent for removing Pb from water and wastewater.
Hossain, A., Ngo, H., Guo, W. & Nguyen, V. 2012, 'Biosorption of Cu(II) From Water by Banana Peel Based Biosorbent: Experiments and Models of Adsorption and Desorption', Journal of Water Sustainability, vol. 2, no. 1, pp. 87-104.
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Banana peel, a discarded agricultural waste was used to produce bioadsorbent through easy and environmental friendly processes. This banana peel based biosorbent was evaluated for adsorptive removal of copper from water and its desorption capability. The characterisation results showed this biosorbent had very high specific surface area, potential binding sites and functional groups. The optimal conditions for biosorption were found at pH 6.5, biosorbent size of less than 75&Icirc;&frac14;, dose of 0.5g/100ml and 1-hour contact time. Thermodynamic analysis also indicated that its adsorption was spontaneous. Significant desorption of copper (94%) was obtained when using 0.1N H2SO4. Both adsorption and desorption equilibrium data were well described by Langmuir, SIPS and Koble-Corrigan models whilst kinetics data by pseudo-first order, Elovich and Intraparticle diffusion models. Models&acirc; parameters were optimised by MATLAB&acirc;s non-linear modelling. All models had good fitness with the experimental data from high R2 (0.970-1.00), low non-linear errors - RMSE (0.004-10.00) and low 2 (0.0004-10.00). The maximum adsorption and desorption capacities were 20.37 and 32.40 mg/g, respectively. The adsorption processes were controlled by chemisorption. Both adsorption and desorption processes could be described by the pseudo-first order kinetic. The potential applicability of banana peel based bioadsorbent could be further examined in a large-scale.
Listowski, A., Ngo, H. & Guo, W. 2012, 'Development of a New Framework and Methodology for Social Assessment of Recycled Water Schemes', Journal of Water Sustainability, vol. 2, no. 2, pp. 149-157.
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The framework and methodology for social assessment follows concepts based on integrated water management and technology as the holistic process. This study was initially undertaken through literature review, collection and analysis of actual data from areas where water reclamation scheme have been in operation. The data obtained helped with identification of information gaps and communication deficiencies. The social assessment of technology might create some controversies, especially over environmental and health impact associated with a long term use of recycled water. This concept also implies that scientific research should support public debate, allowing greater public evaluation of the scheme its implications and consequences. This study could confirm that social assessment of water reclamation and reuse is considered in broad context and it suffers institutional separation and differentiation from economy and technology. It is fair to assert that, political economy and technological research are seen to be quite different from social research and it is often considered in a largely interpret technology and environmental contexts.
Luo, L., Wang, X.C., Guo, W., Ngo, H. & Chen, Z. 2012, 'Impact assessment of excess discharges of organics and nutrients into aquatic systems by thermodynamic entropy calculation', Journal of Environmental Management, vol. 112, pp. 45-52.
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In this study, a method was proposed for calculating the thermodynamic entropy increase DS in a water body after receiving excess discharge of organics and nutrients in order to quantitatively assess the impact of pollutants discharge on aquatic systems. The enthalpy change was evaluated using the standard thermodynamic data according to the possible chemical and/or biochemical reactions such as organic oxidation, nitrification/denitrification, and phosphorus precipitation, for the recovery of water quality to the background level. A series of equations were established for calculating the DS associated with the decomposition or removal of TOC, NO3eN, NO2eN, NH3eN and TP. The values of DS corresponding to unit mass (per g) of these pollutants were calculated as 54.0 kJ/K, 2.91 kJ/K, 10.01 kJ/K, 28.51 kJ/K and 2.81 kJ/K, respectively. Besides, the applicability of the proposed method was proved by a scenario analysis regarding effluent quality control and surface water quality protection in China.
Hossain, A., Ngo, H., Guo, W. & Nguyen, V. 2012, 'Removal of copper from water by adsorption onto banana peel as bioadsorbent', International Journal of GEOMATE, vol. 2, no. 2, pp. 227-234.
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Banana peel, a fruit waste were used to produce bioadsorbent through environment friendly process. It were cut, washed, dried, grounded into powder and used for copper removal. Copper adsorption onto banana peel was depended upon the controlling parameters such as particle size, doses, pH, contact time, agitation speed and temperature. Slightly acidic water (pH = 6) was found to be suitable for copper removal. Equilibrium data were well fitted (R2 = 0.998) with the Langmuir and Freundlich isotherms. The monolayer adsorption capacity was 27.78 mg/g. The calculated RL and `n values has proved the favorability of copper adsorption onto banana peel. Copper adsorption was followed the second order kinetic properly rather than other models. The equilibrium adsorption capacity was 1.439, 8.849, 18.182, 31.250 and 71.429 mg/g when initial copper concentrations were 10, 50, 100, 200, and 400 mg/l respectively. Solvent 0.1N Sulphuric acid showed higher desorption of copper (94%) and adsorption-desorption process can be continued till seven cycles efficiently.
Ma, X.Y., Wang, X.C., Ngo, H. & Guo, W. 2012, 'Application of vibrio qinghaiensis sp. Q67 for ecotoxic assessment of environmental waters: A mini review', Journal of Water Sustainability, vol. 2, no. 4, pp. 209-220.
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Ecotoxicity assessment using luminescent bacteria has been wildly used because it is rapid, sensitive and cost effective for screening water and wastewater quality. This mini-review focused on the application of Vibrio qinghaiensis sp. Q67 (abbreviated as Q67), a natural freshwater luminescent bacteria strain discovered in China. The characteristics of the bioassay using Q67 were firstly reviewed with comparison to that using the Vibrio fischeri, a widely used marine luminescent bacteria strain. In addition to the principal of bioassay using luminescent bacteria, attention was paid to the applications of Q67 to the toxicity assessment of organic and inorganic substances, and practical water samples. With its advantage for direct evaluation of freshwater samples without salt addition, Q67 toxicity test can be a good alternative of Vibrio fischeri for toxicological study of environmental waters.
Nguyen, T., Ngo, H., Guo, W. & Nguyen, V. 2012, 'Phosphorous removal from aqueous solutions by agricultural by-products: A critical review', Journal of Water Sustainability, vol. 2, no. 3, pp. 193-207.
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Phosphorous plays an essential role in the development of living organisms. Nevertheless, phosphorous pollution, known as the eutrophication, is regarded as one of main causes of water quality deterioration. Hence, the decontamination of phosphorous from aqueous solutions is of importance for eutrophication control and phosphorous recovery. This review paper investigates the potential use of agricultural by-products (ABPs) as biosorbents in remediation of phosphorous contaminated waters. It was found that the modified ABPs exhibit equivalent or higher sorption capacity of phosphorous compared to conventional adsorbents. The efficient removal of phosphorous by ABPs requires some chemical modifications. The application of ABPs is highly recommended because of their significant advantages, including the abundant availability, low cost, high efficiency and without detrimental impacts on the environment. As adsorptive removal of phosphorous by ABPs is a relatively new process, there are still many aspects for future research, such as development of novel and cost-effective modification techniques, modeling for process optimization, desorption, cost-benefit analysis etc. The improvements in these aspects are expected to make it the method of choice in the future.
Nguyen, V., Ngo, H., Guo, W., Phuntsho, S. & Li, J. 2011, 'A New Sponge Tray Bioreactor In Primary Treated Sewage Effluent Treatment', Bioresource Technology, vol. 102, no. 9, pp. 5444-5447.
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The new attached growth sponge tray bioreactor (STB) was evaluated at different operating conditions for removing organics and nutrients from primary treated sewage effluent. This STB was also assessed when using as a pre-treatment prior to micro-filtrat
Listowski, A., Ngo, H., Guo, W., Vigneswaran, S., Shin, H. & Moon, H. 2011, 'Greenhouse Gas (GHG) Emissions from Urban Wastewater System: Future Assessment Framework and Methodology', Journal of Water Sustainability, vol. 1, no. 1, pp. 113-125.
Over the last two decades much scientific effort has been expended on the radiative gaseous emissions in the atmosphere. Although there are no regulatory requirements for managing gaseous emissions at present, the long term indications are, that impact relater to air pollution must embrace the broad diversity and challenges associated with urban wastewater cycle management. This study has been considered as a precursor to development of a comprehensive impact assessment of gaseous emission from urban wastewater infrastructure and treatment facilities. It has been carried out in consideration of the future climate change scientific projections, including socio-economic and environmental impacts. Major progress could be gained from systemic approaches in relation to factors influencing emission and the collected data demonstrates correlation between wastewater quality, treatment and energy used with the level of emission. An early attempt was made to attribute environmental impact and costs on per capita basis, as the weight of responsibility to take action is shifting to the community and individuals. The presented framework and methodology offers reliable evaluation of gaseous emissions is an integrated context comprising technology, environment, social and economic factors.
Xing, W., Ngo, H., Guo, W., Listowski, A. & Cullum, P. 2011, 'Evaluation Of An Integrated Sponge - Granular Activated Carbon Fluidized Bed Bioreactor For Treating Primary Treated Sewage Effluent', Bioresource Technology, vol. 102, no. 9, pp. 5448-5453.
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An integrated fluidized bed bioreactor (iFBBR) was designed to incorporate an aerobic sponge FBBR (ASB-FBBR) into an anoxic granular activated carbon FBBR (GAC-FBBR). This iFBBR was operated with and without adding a new starch based flocculant (NSBF) to
Guo, W., Ngo, H., Wu, Z., Yen-Jung, H. & Listowski, A. 2011, 'Application of bioflocculant and nonwoven supporting media for better biological nutrient removal and fouling control in a submerged MBR', Sustainable Environment Research (SER), vol. 21, no. (1), pp. 53-58.
The study aims at modifying a submerged membrane bioreactor (SMBR) with attached-growth nonwoven media and a new green bioflocculant (GBF) (developed at Environmental Engineering R & D laboratory, University of Technology, Sydney) addition to treat a high strength domestic wastewater for reuse. The performance of the SMBR was evaluated in terms of organic and nutrient removal as well as membrane fouling control. The results indicated that the integrated SMBR system could eliminate more than 95% dissolved organic carbon and chemical oxygen demand from the influent. The system achieved 100% of nitrification during 60 d of operation. The denitrification was primarily based on conventional nitrification-denitrification process occurring in the anoxic zone. The total nitrogen removal efficiency and simultaneous nitrification and denitrification were 93 &Acirc;&plusmn; 3 and 96 &Acirc;&plusmn; 1% respectively. Although a relatively long solids retention time (50 d) were adopted, over 98% of total phosphorus in the influent was removed through biological phosphorus removal. The results also show that the addition of GBF could improve microbial activity and reduce membrane fouling. During the experiment, the transmembrane pressure developed marginally (4.5 kPa).
Pham, N., Ngo, H., Guo, W., Ho, D., Mainali, B., Johnston, A.J. & Listowski, A. 2011, 'Responses of community to the possible use of recycled water for washing machines: A case study in Sydney, Australia', Resources, Conservation and Recycling, vol. 55, no. 5, pp. 535-540.
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Recycled water is a valuable resource that has potential to free up potable water supplies and recharge systems while improving the environment. Recycled water for washing machine could be one of the options as new end use of recycled water to alleviate the demand on existing and limited water supplies. This paper summarizes the findings of a research survey in Sydney, Australia to explore the attitudes and opinions of community towards the use of recycled water for different purposes, especially for the washing machine. The survey showed that 97% of the respondents were aware of the persisting water shortage problem while more than 60% of the respondents supported the use of recycled water for washing clothes. This paper exposes the basic concern of participants for using recycled water in washing machine. Health issue was found as the most concerns of the community. The survey also presents the further conditions to be considered for using recycled water for washing machine according to the participants' opinions. Correlation between knowledge and attitudes of respondents was also found in this survey.
Mainali, B., Ngo, H., Guo, W., Pham, N., Wang, X.C. & Johnston, A.J. 2011, 'SWOT analysis to assist identification of the critical factors for the successful implementation of water reuse schemes', Desalination and Water Treatment, vol. 32, pp. 297-306.
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The reuse of urban wastewater has been recognised as an important alternative source of water and is a key aspect of sustainable water policy. As it is a promising innovation, a number of direct and indirect water reuse projects have been instigated and proposed, both nationally and internationally. However there is some uncertainty regarding the effectiveness and impact of these water reuse schemes (WRS). This study investigates the applicability of Strengths, Weaknesses, Opportunities, and Threats (SWOT) as an analysis tool for formulating the critical factors in terms of the implementation of water reuse schemes. Basically, this work adopts an existing multiple case study design method and makes use of SWOT to analyse all critical factors for each selected water reuse scheme. The strengths and weaknesses of successful and unsuccessful WRS are analysed followed by an assessment of the corresponding external opportunities and threats.. On this basis, the critical factors considered for the successful implementation of the WRS are identified. A qualitative investigation using SWOT analysis has therefore been successfully implemented.
Mainali, B., Ngo, H., Guo, W., Pham, N. & Johnston, A.J. 2011, 'Feasibility assessment of recycled water use for washing machines in Australia through SWOT analysis', Resources, Conservation and Recycling, vol. 56, no. 1, pp. 87-91.
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Sustainable urban water consumption has become a critical issue in Australia due to increasing urbanization, the country&acirc;s dry climate and its increasingly variable rainfall. Water recycling is considered vital to alleviate the demand on limited water supplies. The demands on water utilities to develop water recycling capacity and supplies are therefore expected to intensify in Australia. Dual reticulation systems have already been introduced in many cities in Australia and this is likely to expand to many other cities in the future. Developed and proposed dual reticulation schemes in Australia demand the substantial replacement of tap water with recycled water to ensure system optimisation and the sustainability of water supplies. This study successfully applies Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis as a research tool to assess the feasibility of use of recycled water in washing machine applications. Through the identification of the reuse schemes' strengths (elements to leverage and build on) and weaknesses (areas to seek assistance and support) in addition to community opportunities (areas to leverage for program advantages) and threats (elements that could hinder the scheme), the positive aspects for the use of recycled water in washing machines is observed. Further study to address the specific concerns of the general public and the development of guidelines for this new end use is however essential to guide the implementation of recycled water schemes.
Listowski, A., Ngo, H., Guo, W. & Vigneswaran, S. 2011, 'A novel integrated assessment methodology of urban water reuse', Water Science And Technology, vol. 64, no. 8, pp. 1642-1651.
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Wastewater is no longer considered a waste product and water reuse needs to play a stronger part in securing urban water supply. Although treatment technologies for water reclamation have significantly improved the question that deserves further analysis is, how selection of a particular wastewater treatment technology relates to performance and sustainabiiity? The proposed assessment model integrates; (i) technology, characterised by selected quantity and quality performance parameters; (ii) productivity, efficiency and reliability criteria; (iii) quantitative performance indicators; (iv) development of evaluation model. The challenges related to hierarchy and selections of performance indicators have been resolved through the case study analysis. The goal of this study is to validate a new assessment methodology in relation to performance of the microfiltration (MF) technology, a key element of the treatment process. Specific performance data and measurements were obtained at specific Control and Data Acquisition Points (CP) to satisfy the input-output inventory in relation to water resources, products, materiai flows, energy requirements, chemicals use, etc. Performance assessment process contains analysis and necessary linking across important parametric functions leading to reliable outcomes and results.
Nguyen, V., Ngo, H., Guo, W., Listowski, A. & Li, J.X. 2011, 'Evaluation of sponge tray- membrane bioreactor hybrid system for primary treated sewage effluent treatment', Bioresource Technology, vol. in Press, pp. 1-5.
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The membrane bioreactor system (MBR) with pre-treatment of sponge tray bioreactor (STB) was evaluated at different operating conditions for treating primary treated sewage (PTS). The result indicated the successful removal of DOC with the efficiency of higher than 95%. The highest nutrient removal efficiency of 83.6% (NH4-N) and 75.5% (PO4-P) was observed at sludge concentration of 330 mg/L. Specific oxygen uptake rate (SOUR) of activated sludge in MBR kept increasing up to 6 mg O2/g VSS h during stage IV. The sludge volume index (SVI) of less than 100 mL/g during the operation indicated the good settling property of the sludge. At highest sludge concentration of 5 g/L, trans-membrane pressure (TMP) was increasing dramatically during first 15 d up to 25 kPa; however it was only 6 kPa at lower sludge concentrations. It is concluded that the system showed the highest performance at stage III with sludge concentration of 330 mg/L.
Luo, L., Wang, X.C., Guo, W. & Ngo, H. 2011, 'Novel conceptual models for thermodynamic analysis of urban water systems', Journal of Water Sustainability, vol. 1, no. 2, pp. 13-23.
Urban water system (UWS) can be thermodynamically analysed by calculating the entropy budget based on the increase of entropy due to internal and/or external contributions. From different internal and external parts, two novel conceptual models of thermodynamic analysis for an UWS were proposed. For conceptual model 1, natural UWS as a pseudo-reversible process is internal contribution, while the external part of the UWS is artificial water cycle. When the entropy change of the natural UWS is equal to zero, the entropy change of the UWS is considered as the entropy change by the artificial water cycle. The calculations of entropy change for artificial water cycle are based on water balance and purification reactions of selected kinds of typical pollutants in the UWS. For conceptual model 2, the internal entropy change of the UWS is water body, and it is assumed to be zero due to dynamically equilibrium of the water body. The calculation of external entropy change caused by the natural water cycle was proposed to be dependent on meteorological and hydrological data whilst the external entropy change caused by the artificial water cycle could be obtained from mass balance and treatment process analysis.
Chen, Z., Ngo, H., Guo, W., Wang, X.C. & Luo, L. 2011, 'Probabilistic Assessment of Recycled Water Schemes in Australia Using MATLAB Toolbox', Journal of Water Sustainability, vol. 1, no. 3, pp. 333-344.
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Hundreds of recycled water schemes have been successfully established in Australia. However, water quality and risks on human health and the environment associated with particular end uses (e.g. irrigation, industrial uses, non-potable urban uses, groundwater recharges, indirect and direct potable reuses) are still of great concern which can limit the application and extension of recycled water. This study analyses representative recycled water schemes in Australia with regard to the sources and corresponding risks of recycled water, risk assessment approaches as well as practical risk control methods towards various end uses. To quantify the risks, this study proposes a probabilistic assessment approach for existing and future water recycling schemes. With the assistance of MATLAB toolbox, the model was able to fit observed data to probability distribution functions (PDFs) and express the percent removal in PDF rather than point values. This approach could be helpful in quantifying risk or percent removal of potential hazards which involve a degree of variability and randomness. The analytical results, when couple with other environmental assessment tools are convinced to be useful for integrated water planning and management in Australia.
Guo, W., Zhang, R., Vigneswaran, S., Ngo, H. & Kandasamy, J.K. 2010, 'Membranes coupled with physico chemical treatment in water reuse', Water Science and Technology, vol. 61, no. 2, pp. 513-519.
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In this study, short-term experiments were conducted with different configurations of membrane hybrid systems to treat biological treated sewage effluent containing refractory organic pollutants: (i) submerged hollow fiber microfiltration (SMF) alone; (ii) spiral flocculator (SF)-SMF without settling; (iii) SF-PAC-SMF without settling and (iv) SMF with magnetic ion exchange resin MIEXw pretreatment. The results indicated that the pre-flocculation of SF could improve the mitigation of membrane fouling significantly even when the system was operated at a high membrane filtration rate. The transmembrane pressure (TMP) of SF-PAC-SMF only increased marginally (0.8 kPa over 8 hours). SF-SMF without the addition of powdered activated carbon (PAC) also took a relatively long duration for the TMP to increase. The TMP only increased by 2.5 kPa over 8 hours. The SF-PAC-MF system resulted in a high dissolved organic carbon (DOC) removal of more than 96%. When used as pre-treatment to submerged membranes, the fluidized bed MIEXw contactor could remove a significant amount of organic matter in wastewater. This pre-treatment helped to reduce the membrane fouling and kept the TMP low during the membrane operation.
Nguyen, V., Ngo, H., Guo, W., Johnston, A.J. & Listowski, A. 2010, 'Effects of sponge size and type on the performance of an up-flow sponge bioreactor in primary treated sewage effluent treatment', Bioresource Technology, vol. 101, no. 5, pp. 1416-1420.
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The effects of polyurethane sponge size and type on the performance of an up-flow sponge bioreactor were studied using different sponge cube sizes (1 &Atilde; 1 &Atilde; 1 cm, 2 &Atilde; 2 &Atilde; 2 cm and 3 &Atilde; 3 &Atilde; 3 cm) and types of sponge (S28-30/45R, S28-30/60R, S28-30/80R and S28-30/90R). The reactors were operated under anaerobic conditions in an early stage and an aerobic condition in a latter stage. The results indicate that there was no significant difference in the organic and nutrient removal rates between sponge types. The medium size sponge (2 &Atilde; 2 &Atilde; 2 cm) had the best performance in terms of both biomass growth and pollutants removal. Under anaerobic condition, the COD, TN and TP removal efficiencies were up to 70%, 45% and 55%, respectively, and significantly improved under aerobic conditions (e.g. >90% TOC, 95% COD, 65% TN and 90% TP). The external biomass grew faster under anaerobic conditions while internal biomass was dominant under aerobic condition.
Guo, W., Ngo, H., Dharmawan, F. & Palmer, C.G. 2010, 'Roles of polyurethane foam in aerobic moving and fixed bed bioreactors', Bioresource Technology, vol. 101, no. 5, pp. 1435-1439.
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The aim of this study was to investigate the performance of sponge as an active mobile carrier for attachedgrowth biomass in three typical types of aerobic bioreactors to treat a high strength synthetic wastewater. The results show that sponge thickness deteriorated the organic and nutrient removal and 1 cm is the optimumthickness for fixed-bed sponge biofilter (SBF). The sponge volume had significant impact on phosphorus removal rather than organic or nitrogen removal, and 20% volume of sponge could achieve 100% T-P removal within 3 h in a sponge batch reactor (SBR). When sponge coupled with submerged membrane bioreactor (SMBR), the single system show outstanding ammonium (100% at filtration flux of 10 and 15 L/m2 h) and phosphorus (>91% at all fluxes range) removal with optimum pH range of 6&acirc;7
Nguyen, V., Guo, W., Ngo, H. & Vigneswaran, S. 2010, 'A new combined inorganic-organic flocculant (CIOF) as a performance enhancer for aerated submerged membrane bioreactor', Separation and Purification Technology, vol. 75, no. 2, pp. 204-209.
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In this study, a new combined inorganicorganic flocculant (CIOF) of FeCl3 and membrane performance enhancer (MPE50) was prepared and added to an aerated submerged membrane bioreactor (SMBR). The effects of CIOF on the performance of an aerated submerged membrane bioreactor (SMBR) were evaluated. The results indicated that the SMBR with CIOF addition could remove almost 100% total phosphate while eliminating over 90% ammonia (NH4-N) and dissolved organic carbon (DOC) during an 80-day of operation. The respiration tests revealed that the specific oxygen uptake rate (SOUR) was stable around 1.52.0mgO2/gMLVSS h. The sludge volume index (SVI) of less than 100 mL/g during the operation showed the importance of CIOF on the improvement of settling properties of the sludge. Soluble carbohydrate concentration was also well correlated with DOC of the supernatant. CIOF was successful in the reduction of fouling of membrane as the membrane was only chemically cleaned after 53 days of operation.
Xing, W., Guo, W., Ngo, H., Cullum, P. & Listowski, A. 2010, 'Integration Of Inorganic Micronutrients And Natural Starch Based Cationic Flocculant In Primary Treated Sewage Effluent (Ptse) Treatment', Separation Science and Technology, vol. 45, no. 5, pp. 619-625.
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In this study, a natural starch-based cationic flocculant (SBCF) was first evaluated using a granular activated carbon fluidized-bed bioreactor (GAC-FBBR) to treat a high strength synthetic domestic wastewater (primary treated sewage effluent) containing
Xing, W., Ngo, H., Guo, W., Wu, Z., Nguyen, V., Cullum, P., Listowski, A. & Yang, N. 2010, 'Enhancement Of The Performance Of Anaerobic Fluidized Bed Bioreactors (Afbbrs) By A New Starch Based Flocculant', Separation and Purification Technology, vol. 72, no. 2, pp. 140-146.
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In this study, laboratory-scale anaerobic fluidized bed bioreactors (AFBBRs) using granular activated carbon as bedding material were employed for treating a primary treated sewage effluent (PTSE) with or without refractory organic pollutants (ROPs). A n
Guo, W., Xing, W., Ngo, H., Hu, Y.A., Palmer, C.G. & Zhang, R. 2009, 'Enhancement of Organics removal by an Integrated Nonwoven Media Biofiter-submerged Membrane Adsorption Hybrid System', Journal of Applied Membrane Science & Technology, vol. 9, no. 1, pp. 1-8.
Guo, W., Ngo, H., Palmer, C.G., Xing, W., Hu, Y.A. & Listowski, A. 2009, 'Roles of sponge sizes and membrane types in a single stage sponge-submerged membrane bioreactor for improving nutrient removal from wastewater for reuse', Desalination, vol. 249, no. 2, pp. 672-676.
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Sponge not only can reduce membrane fouling by means of mechanical cleaning and maintain a balance of suspended-attached microorganisms in submerged membrane bioreactor (SMBR), but also can enhance dissolved organic matter and nutrient removal. This study investigated the performance of three different sizes of sponge (S28&acirc;30/45R, S28&acirc;30/60R and S28&acirc;30/90R) associated with continuous aerated SMBR. A laboratory-scale single stage sponge-SMBR (SSMBR) showed high performance for removing dissolved organic matter (>96%) and PO4&acirc;P (>98.8), while coarse sponges such as S28&acirc;30/45R, S28&acirc;30/60R could achieve more than 99% removal of NH4&acirc;N. When three-size sponges (S28&acirc;30/45R, S28&acirc;30/60R and S28&acirc;30/90R) were mixed at a ratio of 1:1:1 and in conjunction with two kinds of membranes (0.1 &Icirc;&frac14;m hollow fiber and 2 &Icirc;&frac14;m nonwoven), the SSMBR system has proved its generic merits of superior treated effluent quality and less membrane fouling. The NH4&acirc;N and PO4&acirc;P removal were found excellent, which were more than 99.8% and over 99% respectively. Molecular weight distribution also indicated that major fractions of organic matter could be successfully removed by SSMBR.
Guo, W., Ngo, H., Vigneswaran, S., Dharmawan, F., Nguyen, V. & Aryal, R. 2009, 'Effect of different flocculants on short-term performance of submerged membrane bioreactor', Separation and Purification Technology, vol. 70, no. 3, pp. 274-279.
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This study aims at evaluating the impacts of flocculant addition to a submerged membrane bioreactor (SMBR). Three types of common flocculants (FeCl3, PACl and chitosan) were tested based on the performance of organic and nutrients removal, respiration test and fouling control. The data showed that all of the flocculants not only could keep high removal efficiencies of DOC and COD (>90%) compared to SMBR alone, but also exhibited different advantages and disadvantages according to the properties of the flocculants. For instance, inorganic flocculants strongly affected the nitrification process and organic flocculant addition slightly reduced the phosphorus removal efficiency in SMBR. After adding FeCl3 and PACl, NH4-N removal decreased to 31.9% and 11.1%, while T-N removal dropped to 22% and 0.5% respectively. Although flocculants addition improved sludge settleability and oxygen transfer to some extent, organic flocculant obtained more stable sludge volume indexes (SVI) and specific oxygen uptake rates (SOUR) than those of inorganic flocculants. Inorganic flocculants, on the other hand, led to more reduction of soluble microbial products (SMP) present in mixed liquor and lower membrane fouling rates (1.3 and 2.6 kPa/day for FeCl3 and PACl respectively).
Ngo, H. & Guo, W. 2009, 'Membrane fouling control and enhanced phosphorus removal in an aerated submerged membrane bioreactor using modified green bioflocculant', Bioresource Technology, vol. 100, no. 18, pp. 4289-4291.
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This study aims at developing a modified green bioflocculant (GBF) for membrane fouling control and enhanced phosphorus removal in a conventional aerated submerged membrane bioreactor (SMBR) to treat a high strength domestic wastewater (primary sewage treated effluent) for reuse. The GBF was evaluated based on long-term operation of a lab-scale SMBR. These results showed that SMBR system could achieve nearly zero membrane fouling at a very low dose of GBF addition (500 mg/day) with less backwash frequency (2 times/day with 2-min duration). The transmembrane pressure only increased by 2.5 kPa after 70 days of operation. The SMBR could also remove more than 95% and 99.5% dissolved organic carbon and total phosphorus, respectively. From the respiration tests, it was evident that GBF not only had no negative impact on biomass but also led to high oxygen uptake rate (OUR) (>30 mg O2/L h) and stable specific oxygen uptake rate (SOUR). These results also indicated that GBF had no effect on nitrogen removal and nitrification process.
Listowski, A., Ngo, H., Guo, W., Vigneswaran, S. & Palmer, C.G. 2009, 'Concepts towards a novel integrated assessment methodology of urban water reuse', Desalination and Water Treatment, vol. 11, no. 1-3, pp. 81-92.
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Traditional supplies of large volumes of water and wastewater disposal technologies have offered a linear solution, thus intensifying environmental stress. In addition, provision of urban infrastructure especially any major augmentations are often the impractical or economically prohibitive. Urban water cycle should be viewed as an interactive and coordinated approach involving: Available water resources, Appropriate treatment technology producing fi t for purpose water quality, and Ascertaining long term balance between environmental, social and economic issues.
Ngo, H., Chuang, Y., Guo, W., Ho, D., Pham, N., Johnston, A.J., Lim, R.P. & Listowski, A. 2009, 'Resident's strategy survey on a new end use of recycled water in Australia', Desalination and Water Treatment, vol. 11, no. 1-3, pp. 93-97.
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The concept of using recycled water for washing machine was introduced as a new end use. As there is a noticeable lack social research in understanding the general public perceptions of this application, the residents strategy survey was carried out at some selective suburbs in Sydney with demographically based signifi cant differences of general, gender, age, education, and property style and ownership. The survey indicates that the majority in the community considers the use of recycled water for washing machine is indispensable in view of continuing drought and the associated water shortages. Given safety assurance and demonstration, recycled water for washing machine has a considerable proportion within the responses. The general level of knowledge in community clearly understand that recycled water is more environmentally friendly option, whereas from cleanness and public health point of view, higher quality water is required to be reused in washing machine. Moreover, the residents reckon to have a small unit for pre-treatment (point of use) before recycled water entering washing machines might assure the quality and safety. The survey also shows the major concerns for a resident to use recycled water for washing machine are public health, water cleanness and washing machine durability.
Guo, W., Vigneswaran, S., Ngo, H., Kandasamy, J.K. & Yoon, S. 2008, 'The Role of a Membrane Performance Enhancer in a Membrane Bioreactor: a Comparison with Other Submerged Membrane Hybrid Systems', Desalination, vol. 231, no. 1-3, pp. 305-313.
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Among the membrane processes, membrane bioreactor (MBR) technologies are becoming an innovative and promising option for wastewater treatment and reuse. In this study the performance of the submerged membrane bioreactor was studied with an addition of MPE50, and it was compared against a sponge submerged membrane bioreactor (SMBR) and submerged membrane adsorption bioreactor (SMABR) in terms of TOC removal, COD removal, ammonium nitrogen (NH4-H) removal, orthophosphate (PO4-P) removal, transmembrane pressure (TMP) and oxygen uptake rate. SMBR with MPE50 addition significantly improved the sustainable flux and reduced membrane fouling. The improvement was better than even in the sponge SMBR system. SMBR with MPE50 achieved a high DOC and COD removal efficiency and NH4-N removal. PO4-P removal concentration of 62% initially which increased with time to over 99% after 7 day operation. In terms of phosphorus removal the sponge SMBR system performed better. OUR measurements showed that there was more microbial activity in the SMBR with MPE50 system
Guo, W., Vigneswaran, S., Ngo, H. & Xing, W. 2008, 'Comparison of membrane bioreactor systems in wastewater treatment', Desalination, vol. 231, no. 1-3, pp. 61-70.
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This study investigated the performance of four different membrane bioreactor (MBR) systems, namely floating media biofiltercrossflow microfiltration (FMBCFMF) system, submerged membrane bioreactor (SMBR) alone, submerged membrane adsorption bioreactor (SMABR) and spongeSMBR system, in terms of critical flux. The results indicated that FMB could be used as a pretreatment unit prior to MBR in order to minimize membrane fouling when the FMBCFMF system operates under sub-critical flux condition. The addition of powdered activated carbon (PAC) could maintain the sustainable flux at a lower TMP value (7.5 kPa). However, irreversible fouling occurred when the filtration flux exceeded the critical flux. The addition of 10% volume (reactor volume) fraction of sponge could increase sustainable flux of SMBR system to 2 times.
Xing, W., Ngo, H., Kim, S., Guo, W. & Hagare, P. 2008, 'Adsorption and bioadsorption of granular activated carbon (GAC) for dissolved organic carbon (DOC) removal in wastewater', Bioresource Technology, vol. 99, no. 18, pp. 8674-8678.
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In this study, the performances of GAC adsorption and GAC bioadsorption in terms of dissolved organic carbon (DOC) removal were investigated with synthetic biologically treated sewage effluent (BTSE), synthetic primary treated sewage effluent (PTSE), real BTSE and real PTSE. The main aims of this study are to verify and compare the efficiency of DOC removal by GAC (adsorption) and acclimatized GAC (bioadsorption). The results indicated that the performance of bioadsorption was significantly better than that of adsorption in all cases, showing the practical use of biological granular activated carbon (BGAC) in filtration process. The most significance was observed at a real PTSE with a GAC dose of 5 g/L, having 54% and 96% of DOC removal by adsorption and bioadsorption, respectively. In addition, it was found that GAC adsorption equilibrium was successfully predicted by a hybrid Langmuir-Freundlich model whilst integrated linear driving force approximation (LDFA) + hybrid isotherm model could describe well the adsorption kinetics. Both adsorption isotherm and kinetic coefficients determined by these models will be useful to model the adsorption/bioadsorption process in DOC removal of BGAC filtration system. &copy; 2008 Elsevier Ltd. All rights reserved.
Guo, W., Vigneswaran, S., Ngo, H., Xing, W. & Goteti, P. 2008, 'Comparison of the performance of submerged membrane bioreactor (SMBR) and submerged membrane adsorption bioreactor (SMABR)', Bioresource Technology, vol. 99, no. 5, pp. 1012-1017.
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This study focuses on comparing the performance of submerged membrane bioreactor (SMBR) and submerged membrane adsorption bioreactor (SMABR) over a period of 20 days at a hydraulic retention time (HRT) of 3.1 h. The effects of PAC on critical flux and membrane fouling were also investigated. The SMABR exhibited better results in terms of mixed liquor suspended solids (MLSS) growth, DOC removal (over 96%), COD removal (over 95%), transmembrane pressure (TMP) and oxygen uptake rate. Nearly 100% of bacteria and 100% of total coliforms were removed in both systems. The addition of PAC could maintain the critical flux at a lower TMP value (7.5 kPa), while irreversible fouling caused by PAC occurred when the filtration flux exceeded critical flux.
Ngo, H., Guo, W. & Xing, W. 2008, 'Evaluation of a novel sponge-submerged membrane bioreactor (SSMBR) for sustainable water reclamation', Bioresource Technology, vol. 99, no. 7, pp. 2429-2435.
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A novel sponge-submerged membrane bioreactor (SSMBR) to treat a high strength wastewater for water reclamation was developed in this study. The performance of this system was evaluated using two kinds of polyester-urethane sponges (coarse sponge with hig
Guo, W., Ngo, H., Vigneswaran, S., Xing, W. & Goteti, P. 2008, 'A Novel Sponge-Submerged Membrane Bioreactor (SSMBR) for Wastewater Treatment and Reuse', Separation Science and Technology, vol. 43, no. 2, pp. 273-285.
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Membrane fouling has been regarded as one of the biggest challenges to widespread application of membrane bioreactor (MBR). This study focuses on minimizing the membrane fouling and improving the performance of submerged membrane bioreactor (SMBR) by porous sponge addition. The effects of sponge addition on sustainable flux and membrane fouling were investigated. Acclimatized sponge could significantly increase the suspended growth in SMBR with biomass of 16.7 g/L(sponge). With the sponge volume fraction of 10%, SSMBR could enhance sustainable flux up to 50 L/m2 h compared with sustainable flux of SMBR (only 25 L/m2 h). SSMBR also exhibited excellent results in terms of DOC removal (over 95%), COD removal (over 97%), lower transmembrane pressure development, and oxygen uptake rate. Over 89% of NH4-N and 98% of PO4-P were removed when SSMBR was operated with a MLSS concentration of 15 g/L.
Xing, W., Guo, W., Ngo, H., Listowski, A. & Cullum, P. 2008, 'Specific Anaerobic Fluidized Bed Bioreactors as Pretreatment to Microfiltration in Domestic Wastewater Treatment for Reuse', Journal of Applied Membrane Science & Technology, vol. 8, no. 2, pp. 1-8.
Xia, H., Guo, W., Wu, X., Pi, Y. & Bradford, M.A. 2008, 'Lateral dynamic interaction analysis of a train-girder-pier system', Journal Of Sound And Vibration, vol. 318, no. 4-May, pp. 927-942.
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A dynamic model of a coupled train-girder-pier system is developed in this paper. Each vehicle in a train is modeled with 27 degrees-of-freedom for a 4-axle passenger coach or freight car, and 31 for a 6-axle locomotive. The bridge model is applicable to
Xing, W., Ngo, H., Kim, S., Guo, W. & Hagare, P. 2008, 'Physico - Chemical processes for landfill Leachate Treatment: Experiments and Mathematical Models', Separation Science and Technology, vol. 43, no. 2, pp. 347-361.
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Guo, W., Vigneswaran, S., Ngo, H. & Xing, W. 2007, 'Experimental investigation on acclimatized wastewater for membrane bioreactors', Desalination, vol. 207, no. 1-3, pp. 383-391.
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The inoculation and acclimatization of activated sludge (AS) is one of the vital components to provide preferably suspended aerobic growth and desired treatment mechanism for a treated wastewater using MBR. The performance of a floating media biofilter-s
Vigneswaran, S., Guo, W., Smith, P.J. & Ngo, H. 2007, 'Submerged Membrane Adsorption Hybrid System (smahs) Process Control And Optimization Of Operating Parameters', Desalination, vol. 202, no. 1-3, pp. 392-399.
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This study is to investigate the effect of operating parameters of submerged membrane adsorption hybrid system (SMAHS) such as preadsorption and powdered activated carbon requirement, aeration, filtration flux; There is an optimum value for each of the o
Guo, W., Vigneswaran, S., Ngo, H., Nguyen, V.T. & Ben Aim, R.M. 2006, 'Influence of bioreaction on a long-term operation of a submerged membrane adsorption hybrid system', Desalination, vol. 191, no. 1-3, pp. 92-99.
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This study investigates the long-term performance of a submerged membrane adsorption hybrid system (SMAHS) for organic matter removal from synthetic wastewater representing biologically treated wastewater by using a low dose of powdered activated carbon
Ngo, H., Nguyen, M., Sangvikar, N., Hoang, T. & Guo, W. 2006, 'Simple approaches towards the design of an attached-growth sponge bioreactor (AGSB) for wastewater treatment and reuse', Water Science and Technology, vol. 54, no. 11-12, pp. 191-197.
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Wastewater treatment and reuse is being emphasized due to the shortage of water sources and the continuous deterioration of the aquatic environment. In this study, a novel sponge bioreactor was studied as a low cost, high efficiency alternative for an attached growth biological system. This was designed by combining of number of sponge trays. This emerging technology has many beneficial properties in wastewater treatment and reuse. The approaches towards the conditions for system design were: (i) selection of sponge types; (ii) selection of sponge shapes; and (iii) selection of designated slope of sponge tray. They were determined through a series of experiments using a laboratory-scale unit with synthetic wastewater. It was then tested with a pilot-scale unit at the predetermined optimum conditions. The results indicate that the highest biomass growth was found at the sponge type with a cell count of 7090 cells/in2 (6.45 cm2) The relationship between biomass growth and biological oxygen consumption was well established. The prism-shaped sponge (triangular polyurethane sponge of 7090 cells/in2 with designated slope of sponge tray at 10 degrees) led to the best performance in terms of both organic and nutrient removal efficiency.
Guo, W., Shim, W.G., Vigneswaran, S. & Ngo, H. 2005, 'Effect of Operating Parameters in a Submerged Membrane Adsorption Hybrid System: Experimental and Mathematical Modelling', Journal of Membrane Science, vol. 247, no. 1-2, pp. 65-74.
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This study aims at developing a simple and practical mathematical model to predict the performance of a submerged membrane adsorption hybrid system (SMAHS). Adsorption equilibrium and kinetic studies were first carried out with powdered activated carbon (PAC) for removing, persisting organics from a synthetic wastewater. A series of short-term SMAHS experiments were conducted with preadsorption a[ different operating conditions such as aeration rate, backwash frequency, PAC dose and filtration flux. The Talu adsorption equilibrium and homogeneous surface diffusion model (HSDM) described well the isothermal adsorption behavior and adsorption kinetics. respectively The semi-empirical mathematical model formulated for membrane-adsorption system predicts successfully the performance of SMAHS in terms of total organic carbon (TOC) removal. A coefficient known as "membrane correlation coefficient (MCC)" introduced in the model was found to be very, useful in describing both the adsorption of organics adsorbed onto the PAC and onto the membrane surface. and separation of PAC (with organics adsorbed on it) by the membrane.
Guo, W., Vigneswaran, S. & Ngo, H. 2005, 'Effect of Flocculation and/or adsorption as pretreatment on the critical flux of crossflow microfiltration', Desalination, vol. 172, no. 1, pp. 53-62.
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Guo, W., Vigneswaran, S., Ngo, H. & Chapman, H.A. 2004, 'Experimental Investigation Of Adsorption-Flocculatio-Microfiltration Hybrid System In Wastewater Reuse', Journal of Membrane Science, vol. 242, pp. 27-35.
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Shon, H., Guo, W., Vigneswaran, S., Ngo, 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.