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Professor Huu Hao Ngo

Biography

Ngo is an academic with more than thirty five years' professional experience in Australia and in Asian countries. Presently, Ngo is Professor of Environmental Engineering and serving as Deputy Director of Centre for Technology in Water and Wastewater. He is also Acting Deputy Head, Reserch,School of Civil and Environmental Engineering, Faculty of Engineering and Information Technology.

Ngo is internationally well known for his activities in the areas of wastewater treatment and reuse technologies, which include advanced biological waste treatment (aerobic and anaerobic membrane bioreactors, specific attached and/or suspended growth bioreactors, biosorption, wetland), membrane technologies (membrane hybrid system, desalination), and physical-chemical separation technologies as pretreatment or post-treatment (adsorption, flocculation and filtration).

Ngo’s expertise and practical experience also covers the areas of solid waste management, alternative water resources, water management, treatment and impact assessment, and pollution control. In addition, he has demonstrated a significantly leading role in the sustainable water research team and provided useful advice on the theoretical and technical concepts of system design and experimental configuration as well as mathematical models. Currently, he focuses more on developing specific green technologies: water – waste – bioenergy nexus and greenhouse gas emission control.

He has been awarded 54 external and 15 internal grants which accrued research income of over A$ 3.9 million. Ngo has successfully supervised postdoctoral reserchfellows, postgraduate students and a large number of capstone project students. He has been invited to give numerous Plenary/keynote/Invited speeches, seminars and lecturers in the international conferences and the universities/research institutions.

Ngo has published more than 400 technical papers (including 4 books, > 28 book chapters and several patents). Ngo's editorial abilities are international recognised through his appointment of an Editor of Bioresourse Technology, Elsevier (one of the top impact international journals in the environmental field). He is also a founder and Editor in Chief of Journal of Water Sustainability (UTS and Xi’an University of Architecture and Technology). In addition, he is also serving as an editorial board member of Science of the total Environment, Elsevier, Environmental Nanotechnology, Monitoring and management, Elsevier, Journal of Chemistry, Journal of abvanced in Environmental Chemistry, Hindawi, International Journal of Energy and Environmental Sustainability, the International Society for Energy, Environment and Sustainability (ISSES).

Professional

Professional Memberships

  • Council member of International Forum on Industrial Bioprocess (IFIBiop)
  • Member of International Water Association (IWA)
  • Managing Committee Member of IWA Working Group on Alternative Water Resources (China)
  • Member of Australian Water Association (AWA)
  • Member of American Chemical Society (ASC)
  • Member of American Association of Science for the Advancement of Science (AAAS)
  • Member of European Desalination Society (EDS)
  • Life member of International Forum on Industrial Bioprocess
  • International member of the 21st Century Centre of Excellence (COE) on Global Renaissance by Green Energy Revolution, Japan

Assessor

Australian Laureate Fellowship, Australian Future Fellowships, Australian Research Council (ARC) Discovery Projects; ARC Linkage Projects, ARC Discovery Early Career Researcher Award; The Innovation and Technology Support Programme (ITSP) Projects-Hong Kong; International Forum on Industrial Bioprocess Fellowships; Foundation for Science and Technology Development of Ton Duc Thang University; National and Global PhD and Masters theses.  

Journal Editor

  • Editor of Bioresource Technology (BITE), Elsevier (Impact Factor = 4.917)
  • Editor-in-Chief of Journal of Water Sustainability (JWS), UTS and XAUAT

Editorial Member

  • Editorial board member, Science of the Total Environment, Elsevier (Impact Factor = 3.976)
  • Editorial Board Member of Environmental Nanotechnology, Monitoring and management, Elsevier
  • Editorial Board Member of Journal of Chemistry, Hindawi (Impact Factor = 0.772)
  • Editorial Board Member of Journal of Advances in Environmental Chemistry, Hindawi
  • Editorial Board Member of International Journal of Energy and Environmental Sustainability, the International Society for Energy, Environment and Sustainability (ISSES)

Guest Editor

  • Guest Editor, Special issue on "Renewable Energy", the 2nd International Conference on Bioenergy, Environment and Sustainable Technologies (BEST, 2015)
  • Guest Editor for the International Conference on Emerging Trends in Biotechnology (ICETB-2014), Indian Journal of Experimental Biology (IJEB), Special issue on Emerging Trends in Biotechnology”, 53 (5), 2015
  • Guest Editor for CESE (International Conference on Challenges in Environmental Science & Engineering) in Special Issues of BITE (2009)

 :Book Editor 

  • Editor for a new book series titled as New and Future Developments in Biotechnology and bioengineering, Volume IVA: Biological Treatment of Industrial Effluents to be published by Elsevier (2015).
  • Principal Editor for the book entitled “Green Technologies for Sustainable Water Management”, American Society of Civil Engineers (ASCE) (2016)

Honour and Award 

  • Honorary Co-Direction, World Collaborative Membrane Bioreactor Centre, Tongji University, University of Technology Sydney and Tianjin Polytechnic University, 2016
  • Vice Chairman, the Academic Committee of the International Science & Technology Cooperation Centre for Urban Alternative Water Resources Development, Xi’an University of Architecture and Technology, China, 2016 
  • Best Paper Award, Elsevier, Bioresource Technology, 2016
  • Outstanding Contribution in Reviewing Award, Elsevier, Science of The Total Environment, 2015
  • FEIT 2015 Publication Award for High Impact and Citations in Scopus, UTS, 2015
  • International expert, Xi’an University of Architecture and Technology, China, 2015
  • University Foreign Experts, Tianjin Chengjian University, Tianjin, China, 2015
  • Adjunct Professor, Ton Duc Thang University (TDUT), Viet Nam 2015
  • Evaluation expert of FOSTECT (Foundation for Science and Technology Development of Ton Duc Thang University), Viet Nam, 2014
  • Honorary Guest Professor, Tianjin University, China, 2014
  • Honorary Guest Professor, Jinan University, China, 2014
  • FEIT 2014 HDR (Higher Degree Research) Supervision Award, UTS, 2014
  • University Foreign Experts, Tianjin Polytechnic University, Tianjin, China, 2014
  • Honorary International Chair Professor, National Taipei University of Technology, China, 2014
  • Advisory Committee Member, Tianjin Engineering center of Biomass-derived Gas/Oil Technology, 2014
  • Honorary Guest Professor, Xi’an University of Architecture and Technology, China, 2013
  • Outstanding Editorship performance Award, Bioresource Technology, Elsevier, 2013
  • Outstanding Contribution Award in Southeast Asia, International Training and Research Program for sustainable development on biofuel and environmental technologies, Taipei, Taiwan, 2012, 2013 and 2014.
  • Outstanding Contribution Award in the 5th Challenges in Environmental Science and Engineering, Melbourne, 2012
  • UTS UniQuest Trailblazer Winner and Finalist of National UniQuest Trailblazer, 2011
  • UTS - Finalist, Research Excellence through Industry Partnership Award, 2010
  • UniQuest Trailblazer Runner Up, Open category, 2009
  • IWA East Asia & Pacific Applied Research Honour Award, 2008
  • Elsevier’s BITE Top Reviewer in 2007
  • Certificate of Merit - Best Paper of The Technical Session, the International Cleaner Technologies and Environmental Management,  Pondicherry, India, 2007
  • UTS, Faculty of Engineering Staff Award for Excellence, 2006
  • Top 5 researchers in the 2004-2005 as a leading researcher in UTS Key Research Strength on Water and Waste Management in Local Communities, the Institute of Water and Environmental Resource Management
  • AAS-French Embassy Award, Australian Academy of Science and French Embassy fellowship, 2002
  • AAS-JSPS Award, Australian Academy of Science and Japan Society for the Promotion of Science Exchange program – Fellowship, 2000
  • AAS-KOSEF Award, Australian Academy of Science and Korean Science and Engineering Foundation Exchange Program – Fellow, 1998

International Conference Plenary/Keynote/Invited Speaker

2016: The 5th IWA Regional Membrane Technology Conference, Kunming, China

2016: The 12th World Filtration Congress, Taipei, Taiwan

2016: National Taiwan Filtration and Separation Society, Taipei, Taiwan

2015: The International Conference on New Horizons in Biotechnology, Trivandrum, India

2015: The international Environmental Engineering Conference, Busan, Korea

2015: The 3rd Great Cycle 2015, Beijing, China

2015: The IWA Alternative Water Resource, Nanjing, China

2015: The 1st MBR Workshop, MBRC, Tianjin Polytechnic University, China

2014: The 4th IWA Regional Membrane Technology Conference, Ho Chi Minh City, Viet Nam

2014: International Workshop on Bioenergy and Environment, Tianjin, China

2014: Specific Seminars on Innovative Bioreactors for Future Green Bioprocess, NCKU, Taiwan

2013: International Symposium Re-Water 2013, Braunschweig, Germany

2013: International Conference on Health, Environment & Industrial Biotechnology, Allahabad, India

2013: International Conference on Challenges in Environmental Science & Engineering (CESE), Korea

2013: The Exceed Expert Seminar “Water issues in Mega Cities”, Ho Chi Minh City, Viet Nam

2013: International Conference on Bioenergy, Environment & Sustainable Technologies, Tiruvannamalai, India

2012: The international Conference on Industrial Biotechnology, Patiala, India

2012: The international Conference on Sustainability Science in Asia, Bali, Indonesia

2011: The International Conference on New Horizons in Biotechnology, Trivandrum, India

2009: The International Conference on Challenges in Biotechnology and Food Technology, Annamalai, India

2007: The International Conference on Cleaner Technologies and Environmental Management, Pondicherry, India

2006: The Symposium for the 21st Century Centre of Excellence Program on “Global Renaissance by Green Energy Revolution” Nagaoka, Japan

2001: The Environmental Management and Pollution Abatement, Madras

International Conference Co-Chair:

2015: International Conference on Challenges in Environmental Science & Engineering (CESE), Sydney, Australia

International Conference Theme Co-Chair:

2010, 2011, 2012: International Conference on Challenges in Environmental Science & Engineering (CESE)

International Conference Committee Member:

2016: 1st International Conference Bioresource Technology for Bioenergy, Bioproducts & Environmental Sustainability, Sitges, Spain

2016: Eurobiomass, Birmingham, UK.

2016: The 12th World Filtration Congress, Taipei, Taiwan

2015: International Organising Committee member of the International Conference on New Horizons in Biotechnology, Trivandrum, India

2015: Executive Committee member: The international Environmental Engineering Conference, Busan, Korea

2015: Scientific Committee member of the IWA Alternative Water Resources Conference (IWA-AWR2015), Nanjing, China

2015: Scientific Committee member and Organising Committee member of the 1st MBR Workshop, Tianjin, China

2015: Scientific Committee member of International Conference - the 5th Environmental Technology and Management Conference (ETMC-2015) in Bandung, Indonesia

2015: Advisory committee member of the International Conference on Advances in Biotechnology, Civil and Mechanical Science (BCMS-2015), Namakkal , Tamil Nadu, India

2015: The International Advisory Committee of the 2nd International Conference on Bioenergy, Environment and Sustainable Technologies (BEST2015), Tiruvannamalai. India

2014: Scientific Committee member of the 4th IWA Regional Conference on Membrane Technology, Ho Chi Minh, Viet Nam

2014: 10th European Symposium on Biochemical Engineering Sciences and 6th International Forum on Industrial Bioprocesses, Lille, France 2 France

2013: IWA Conference on Alternative Water Resources Management and Integrated Technologies for Sustainable Urban Water System, Qingdao, China

2012: Industrial Biotechnology, Patiala, India

2012: The 5th International Industrial Bioprocesses, Taipei, Taiwan

2011: IWA International Conference, Cities of the future Xi’An, China;

2011: the 8th IWA International Symposium on Waste Management Problems in Agro-Industries, Cesme, Turkey

2009: International Scientific Board Member of CESE, Townsville, Australia

2009: International Scientific Board Member of the International Conference on Challenges in Biotechnology and Food Technology (CBFT, 2009), Annamalai, India

2007: International Advisory Committee and an anchor of discussion panel, International Conference on Cleaner Technologies and Environmental Management, Pondicherry, India

            Off-shore Seminars/Lecturers:

  • Korea (e.g. Chonnam National University, Korea Advanced Institute of Science and Technology, Gwangju Institute of Science and Technology, Myongchi University, Gwangju Water Research Centre etc.),
  • China (e.g. Tsinghua University, Tongji University, Shandong University, Tianjin Univesity, Tianjin Polytechnic University, Xi’an University of Architecture and Technology, Jinan University, Chinese Research Academy of Environmental Sciences etc.),
  • Hong Kong (HKMA Li Ka-Shing College of Professional & Continuing Education)
  • Japan (e.g. Metropolitan Tokyo Institute of Technology, Nagaoka University etc.)
  • Taiwan (e.g. National Taiwan University, Chung Yuan University, Chengkung National University, Chia Nan University, National Taipei University of Technology etc.) 
  • Vietnam (e.g. the Exceed Expert Seminar – Water issues in Mega Cities – Viet Nam National University – Ho Chi Minh City – Institute for Environment and Water Resources, Da Lat University etc.)
Image of Huu Hao Ngo
Professor, 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
Member, American Chemical Society
 
Phone
+61 2 9514 2745

Research Interests

Water and wastewater treatment and reused technologies, bioenergy, greenhouse gas emission control, water and wastewater quality monitoring and management, treatment technology assessment, environmental impact assessment, solid waste management, desalination

Can supervise: Yes
Presently, Ngo is supervising 1 postdoctoral research fellow, 5 PhD students (as principal supervisor) and  2 PhD  and 1 Masters students (as co-supervisor), and more than 15 capstone project students per year.

Civil and Environmental Engineering

Books

Lee, D.J., Hallenbeck, P.C., Ngo, H.H., Jegatheesan, V. & Pandey, A. 2016, Current Developments in Biotechnology and Bioengineering: Biological Treatment of Industrial Effluents.
© 2017 Elsevier B.V. All rights reserved.Current Developments in Biotechnology and Bioengineering: Biological Treatment of Industrial Effluents provides extensive coverage of new developments, state-of-the-art technologies, and potential future trends in data-based scientific knowledge and advanced information on the role and application of environmental biotechnology and engineering in the treatment of industrial effluents. These treatment processes have been broadly classified under aerobic and anaerobic processes which determines the scope and level of pollutant removal. Chapters in this volume review the most recent developments and perspectives at different environmental cleanup operation scales. Outlines available biochemical processes for the treatment of solid industrial waste Covers aerobic and anaerobic treatments, their mechanisms, and selection criteria Highlights specific industrial applications, such as anammox processes.
Lee, D.J., Hallenbeck, P.C., Ngo, H.H., Jegatheesan, V. & Pandey, A. 2016, Preface.
View/Download from: Publisher's site

Chapters

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.
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...
Ngo, H., Vigneswaran, S. & Sundaravadivel, M. 2007, 'Advanced Treatment Technologies for Recycle/Reuse of Domestic Wastewater' in Vigneswaran, S.V. (ed), Wastewater Recycle, Reuse, and Reclamation, Eolss Publishers Co., Ltd.,, UK, pp. 77-98.
Vigneswaran, S., Ngo, H., Visvanathan, C. & Sundaravadivel, M. 2007, 'Quantity and Quality of Drinking Water Supplies' in Vigneswaran, S.V. (ed), Wastewater Recycle, Reuse, and Reclamation, Eolss Publishers Co., Ltd.,, UK, pp. 24-36.
Vigneswaran, S., Ngo, H., Visvanathan, C. & Sundaravadivel, M. 2007, 'Conventional Water Treatment Technologies' in Vigneswaran, S.V. (ed), Wastewater Recycle, Reuse, and Reclamation, Eolss Publishers Co., Ltd.,, UK, pp. 37-56.
Vigneswaran, S., Ngo, H., Chaudhary, D.S. & Hung, Y. 2005, 'Physicochemical Treatment Processes for Water Reuse' in Wang, L.K., Hung, Y.T. & Shammas, N.K. (eds), Physicochemical Treatment Processes, Humana Press, Totowa, New Jersey, USA, Totowa, New Jersey, USA, pp. 635-676.
Vigneswaran, S. & Ngo, H. 2000, 'Technologies for domestic wastewater treatment and reuse' in Goosen, F.A. & Shayya, W.H. (eds), Water Management, Purification & Conservation in Arid Climates, Technomic Publishing Co., Inc., USA, pp. 123-151.

Conferences

Cong, N.N., Thi, H.N., Chen, S.-.S., Chan, W.-.H., Ngo, H.H. & Guo, W. 2014, 'Step forward to the improvement of osmosis membrane bioreactor for sustainable water', ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 248th National Meeting of the American-Chemical-Society (ACS), AMER CHEMICAL SOC, San Francisco, CA.
Nguyen, T.V., Rahman, A., Vigneswaran, S., Ngo, H.H., Chang, J.S. & Chang, C.Y. 2010, 'The uptake of arsenite by coprecipitation and adsorption on iron oxide coated sponge', Arsenic in Geosphere and Human Diseases, As 2010 - 3rd International Congress: Arsenic in the Environment, pp. 450-452.
Nguyen, V., Tran, T.T., Pham, T.L., Vigneswaran, S., Ngo, H., Nguyen, H. & Nguyen, D.T. 2009, 'Use of a Novel Ferrous-Ferric oxide Material from Waste of Iron Ore Mining for Arsenic Removal', The 3rd IWA-ASPIRE Conference & Exhibition (IWA-ASPIRE 2009), The 3rd IWA-ASPIRE Conference & Exhibition (IWA-ASPIRE 2009), IWA, Taiwan, pp. 1-9.
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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Nguyen, V., Vigneswaran, S. & Ngo, H. 2008, 'A Novel Iron Oxide Coated Sponge Adsorption System To Remove Arsenic From Drinking Water', Proceedings of the World Water Congress and Exhibition 2008, IWA World Water Congress, International Water Association (IWA), Vienna, Austrlia, pp. 1-8.
Millions of people worldwide are at risk from the presence of arsenic in groundwater. There is a global need to develop appropriate technologies to remove arsenic from water for household and community water supply systems. In this study, a new material namely iron oxide coated sponge (IOCSp) was developed and used to remove As. It was found that IOCSp has a high capacity in removing both As (V) and As (III). The adsorption capacity of IOCSp was up to 4.6 mg As/g IOCSp, higher than a number of other materials. A filter packed even with very small amount of 25 g IOCSp maintained a consistent arsenic removal efficiency of 95% from synthetic water containing arsenic concentration of as high as 1,000μg/L. This produced a throughput volume of 153 and 178L of water containing As(III) and As(V) respectively before any need for regeneration or disposal of IOCSp. It was found to provide comparable results with advanced technologies such as nanofiltration system with in line addition of nano zero valent iron. In addition, the initial results also showed that the exhausted IOCSp can safely be disposed of through the solidification/stabilization technique.
Ho, D.P., Vigneswaran, S., Ngo, H., Shon, H. & Kandasamy, J.K. 2008, 'Adsorption and Photocatalysis Kinetics of UV Light Responsive and Visible Light Responsive Titanium Dioxide in Wastewater Treatment', Proceedings of the IWA World Water Congress and Exhibition 2008, IWA World Water Congress, International Water Association (IWA), Vienna, Austria, pp. 1-8.
The possible use of photocatalysis with TiO2 in wastewater treatment has been the focus of numerous studies in recent years. In this study, the adsorption and photocatalytic oxidation of organic compounds by UV light responsive titanium dioxide (P25) and visible light responsive titanium dioxide (Vis-TiO2) were investigated. Firstly, the adsorption behavior of the two photocatalysts was examined by the adsorption isotherm and kinetics experiments. The photocatalytic reactivity of the catalysts was then compared at different operating conditions. The results indicate that Freundlich model well described the adsorption capacity of both materials. The photocatalytic kinetics showed that the highest removal of NOM was achieved at an optimum concentration of 1.0 g/L of both photocatalysts. In case of P25, one-hour irradiation of UV light at the intensity of 184.64 mW/cm2 resulted in approximately 57% of TOC removal. It was observed that visible light photoexciting Vis- TiO2 required a longer irradiation time of 2 days to remove 65% of organic matters.
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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Kim, S., Nguyen, V., Vigneswaran, S. & Ngo, H. 2007, 'Adsorption Equilibrium, Kinetics and Thermodynamics of Iron-coated Sponge (IOCSp) for Removal of As (III)', Proceedings of International Conference on Cleaner Technologies and Environmental Management (ICCTEM 200), International Conference on Cleaner Technologies and Environmental Management, Allied Publishers Pvt. Ltd., India, pp. 44-50.
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Sangvikar, N., Hagare, P. & Ngo, H. 2007, 'Fibre Cement Industrial Water Recovery: A viable Alternative Water Source', Proceedings of International Conference on Cleaner Technologies and Environmental Management, International Conference on Cleaner Technologies and Environmental Management, Allied Publishers Pvt. Ltd., India, pp. 1-7.
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Australian water demands are increasing significantly with the increase of urbanization and industrialization. Thus, water is a valuable resource in Australia, but in short supply. There is a scope to make better use ofrecycled water as an additional water resource. Water reclamation is the best sustainable solution for water crisis. The recirculation of wastewater to reusable water can be achieved by implementing specific wastewater treatment technologies/or wastewater recycling for non-potable purposes.
Zhang, R., Vigneswaran, S., Ngo, H.H. & Nguyen, H. 2005, 'Magnetic ion exchange (MIEX (R)) resin as a pre-treatment to a submerged membrane system in the treatment of biologically treated wastewater', DESALINATION, International Congress on Membranes and Membrane Processes, ELSEVIER SCIENCE BV, Seoul, SOUTH KOREA, pp. 296-302.
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Shon, H., Vigneswaran, S., Kim, J., Ngo, H. & Park, N. 2004, 'Comparison of Nanofiltration with Flocculation-Microfiltration-Photocatalysis Hybrid System in Dissolved Organic Matter Removal', 9th World Filtration Congress, World Filtration Congress, The American Filtration and Separation Society, New Orleans, Louisiana, USA, pp. 1-19.
Shon, H., Vigneswaran, S., Kim, I.S., Cho, J. & Ngo, H. 2004, 'Characterization of Different Treatments With Biologically Treated Sewage Effluent and Synthetic Wastewater', Enviro 04 Convention & Exhibition, Enviro 04, Enviroaust Convention Limited, Darling Harbour, Australia, pp. 1-10.
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.
Nguyen, V., Vigneswaran, S., Ngo, H., Pokhrel, D. & Viraraghavan, T. 2004, 'Arsenic Removal by Iron Coated Sponge in Drinking Water Treatment', The 2nd International Symposium on Southeast Asian Water Environment, The Second International Symposium on Southeast Asian Water Environment, The University of Tokyo, Hanoi, Vietnam, pp. 214-221.
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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Shon, H., Vigneswaran, S., Ngo, H. & Ben Aim, R.M. 2003, 'Low Pressure Nanofiltration with Adsorption As Pretreatment In Tertiary Wastewater Treatment for Reuse', IMSTEC 2003, International Membrane Science and Technology Conference, AWA-UNESCO Membrane Centre, Sydney, Australia, pp. 1-7.
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Shon, H., Vigneswaran, S., Ngo, H. & Kim, I.S. 2003, 'Effect of high rate Pre-Treatment on Nanofiltration Systems in Wastewater Reuse', ASIAN WaterQual 2003, IWA Asia-Pacific Regional Conference, IWA-Regional Publication, Bangkok, Thailand, pp. 1-9.
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.
Shon, H., Vigneswaran, S., Ngo, H., Kim, D., Park, N.E., Jang, N.J. & Kim, I.S. 2003, 'Characterisation of Effluent Organic Matter (EFOM)Of Fouled Nanofilter (NF) Membranes', IMSTEC2003, Fifth International Membrane Science and Technology Conference, AWA-UNESCO Membrane Centre, Sydney, Australia, pp. 1-6.
Maheswaran, S.M., Yadav, N.N., Shutthanandan, V., Thevuthasan, S., Hart, T.R., Ngo, H. & Vigneswaran, S. 2003, 'Evaluating the use of induced X-ray emission (PIXE) technique in quantifying the arsenic in an adsorbent', ASIAN WaterQual2003, IWA Asia-Pacific Regional Conference, IWA-regional publication, Bangkok, Thailand, pp. 1-8.
Thiruvenkatachari, R., Ngo, H.H., Hagare, P., Vigneswaran, S. & Ben Aim, R. 2002, 'Flocculation-cross-flow microfiltration hybrid system for natural organic matter (NOM) removal using hematite as a flocculent', DESALINATION, pp. 83-88.
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Ngo, H.H., Vigneswaran, S., Hu, J.Y., Thirunavukkarasu, O. & Viraraghavan, T. 2002, 'A comparison of conventional and non-conventional treatment technologies on arsenic removal from water', Water Science and Technology: Water Supply, pp. 119-125.
In this study, four treatment methods were used to remove arsenic from water, namely: (i) chemical precipitation, (ii) arsenic adsorption onto iron-oxide-coated sand, (iii) high-rate saturated floating-medium flocculator/filter and (iv) membrane hybrid system (adsorption-microfiltration). The results indicated that more than 90% of total arsenic was removed by using FeCl3 (40 mg/L) as coagulant. The removal efficiency was 10% lower when polysilicato-iron (PSI, 2.5 mg/L) was used as a flocculant. The results of both the batch and column adsorption studies showed that iron-oxide-coated sand can effectively be used to achieve very high levels of arsenic removal (less than 5 m/L as As in drinking water). Arsenic was removed up to 78% from the packed polystyrene beads filter with in-line FeCl3 addition at a high loading rate of 30 m3/m2.h. When powder activated carbon (PAC) was used in the membrane hybrid system, 87% removal of arsenic was achieved. A mixing time of 2.7 min with the mixing intensity of 87.8 s-1 were used. A very high filtration (permeate flux of 760 L/m2.h) was observed with a membrane of pore size of 0.2 m.
Jegatheesan, V., Lamsal, P.R., Visvanathan, C., Ngo, H.H. & Shu, L. 2002, 'Effect of natural organic compounds on the removal of organic carbon in coagulation and flocculation processes', 3RD WORLD WATER CONGRESS: DRINKING WATER TREATMENT, 3rd World Water Congress of the International-Water-Association, I W A PUBLISHING, MELBOURNE, AUSTRALIA, pp. 473-479.
Bidkar, A., Vigneswaran, S., Milne-Home, W.A., Ngo, H. & Moon, H. 2000, 'Adsorption of Metsulfuron-Methyl on Granular Activated Carbon', Proceedings of the 4th International Symposium on Environmental Geotechnology and Global Sustainable Development, CEEST, Boston (Danvers), Massachusetts, USA, pp. 1079-1086.
Jegatheesan, V., Ngo, H. & Vigneswaran, S. 2000, 'High rate filtration using buoyant medium: experiments and mathematical models', Critical Technologies to the World in 21st century: Pollution Control and Reclamation in process industries, International Water Association, Beijing, China, pp. 0-0.
Vigneswaran, S., Kwon, D.Y., Ngo, H.H. & Hu, J.Y. 2000, 'Improvement of microfiltration performance in water treatment: Is critical flux a viable solution?', Water Science and Technology, pp. 309-315.
In this study, three definitions for critical flux were introduced based on the crossflow microfiltration (CFMF) experiments conducted under an operational mode of constant permeate flux. The critical flux based on material balance was calculated from the rate of particles deposition. The highest permeate flux results in no particle deposition being taken at the critical flux. The second definition was based on the increase in transmembrane pressure (TMP). The critical flux based on the TMP increase is the flux below which the membrane fouling does not occur. The third definition was based on the direct observation of particles deposition through microscope. Detailed experiments were conducted with synthetic suspension of different sizes of latex particles. Long term experiments conducted with polydispersed kaolin clay suspension indicated that the critical flux based on material balance concept is more realistic in field conditions.
Ngo, H.H., Vigneswaran, S., Kim, S.H., Bidkar, A. & Moon, H. 2000, 'Microfiltration-adsorption hybrid system in organics removal from water', Water Science and Technology, pp. 51-57.
A series of experiments was conducted with a Millipore flat plate microfiltration module modified to incorporate in-line powdered activated carbon (PAC) addition In-line PAC was mixed continuously through a spiral mixing device for a predetermined time prior entering a membrane unit. The results showed that this system is excellent in removing fulvic acid (FA). This system provides to sufficient contact time for PAC to adsorb organics compared to the system with in-line adsorbent addition. More than 85% of FA was removed from water containing 8 mg/l of FA. To achieve this following conditions were used:.(i) a velocity gradient G (mixing intensity) of 160.4 s-1; (ii) a hydraulic residence time (mixing time) of 4 minutes; (iii) a PAC dose of 260 mg/l; and (iv) membrane pore size of 0.22 m. In case of low FA concentration (e.g. 1.2 mg/l) in water, the removal efficiency was almost 100%. The removal efficiency also increased with the increase of mixing intensity and mixing timer. The permeate flux slightly improved when a membrane of pore size 0.22 m was used with shorter hydraulic residence time and lower PAC concentration. This paper presents a mathematical model developed based on surface diffusion. The model successfully predicted the performance of this hybrid system.
Vigneswaran, S., Jegatheesan, V., Santhikumar, S., Ngo, H.H., Ben Aim, R. & Shanoun, A. 1999, 'Floating medium flocculator/filter: Is unsaturated flow regime superior to saturated flow regime?', ENVIRONMENTAL HYDRAULICS, pp. 777-782.
Manandhar, U.K., Vigneswaran, S. & Ngo, H.H. 1998, 'Mathematical modelling of declining rate filtration', ENVIRONMENTAL HYDRAULICS, 2nd International Symposium on Environmental Hydraulics, A A BALKEMA PUBLISHERS, UNIV HONG KONG, DEPT CIVIL ENGN, HONG KONG, PEOPLES R CHINA, pp. 783-787.
Bolto, B.A., Ngo, H.H. & Vigneswaran, S. 1997, 'Drinking water production with a dual floating medium-sand filter system', CHEMISTRY FOR THE PROTECTION OF THE ENVIRONMENT 3, 11th International Conference on Chemistry for Protection of the Environment, PLENUM PRESS DIV PLENUM PUBLISHING CORP, CAIRO, EGYPT, pp. 1-8.
Ngo, H.H., Vigneswaran, S. & BenAim, R. 1996, 'Effect of floc size on the applicability of direct filtration in water and tertiary wastewater treatment', 7TH WORLD FILTRATION CONGRESS, PROCEEDINGS, VOLS I AND II, 7th World Filtration Congress, HUNGARIAN CHEMICAL SOC, BUDAPEST, HUNGARY, pp. 157-161.

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.', Environ Sci Pollut Res Int, 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.
Hu, Y., Wang, X.C., Sun, Q., Ngo, H.H., Yu, Z., Tang, J. & Zhang, Q. 2017, 'Characterization of a hybrid powdered activated carbon-dynamic membrane bioreactor (PAC-DMBR) process with high flux by gravity flow: Operational performance and sludge properties.', Bioresour Technol, vol. 223, pp. 65-73.
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Three PAC-DMBRs were developed for wastewater treatment under different PAC dosages with biomass concentrations averaged at 2.5, 3.5 and 5.0g/L. The DMBRs could be continuously operated at 40-100L/m(2)h, while higher fluxes were obtained within the PAC-DMBRs with hydraulic retention times varying in 4-10h. A dose of 1g/L PAC brought about obvious improvement in the sludge particle size distribution, settling, flocculating and dewatering properties due to the formation of biological PAC, and the sludge properties were further improved at a higher PAC dose (3g/L). The addition of PAC notably shortened the DM formation time after air backwashing and enhanced pollutant removal. Moreover, under a long solid retention time (approximately 150d), the concentrations of both soluble and bound extracellular polymeric substances (EPS) decreased substantially because of the adsorption and biodegradation effects of the biological PAC. No obvious impact on biomass activity was observed with PAC addition.
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.
Vu, T.M., Trinh, V.T., Doan, D.P., Van, H.T., Nguyen, T.V., Vigneswaran, S. & Ngo, H.H. 2017, 'Removing ammonium from water using modified corncob-biochar', Science of the Total Environment, vol. 579, pp. 612-619.
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Ammonium pollution in groundwater and surface water is of major concern in many parts of the world due to the danger it poses to the environment and people's health. This study focuses on the development of a low cost adsorbent, specifically a modified biochar prepared from corncob. Evaluated here is the efficiency of this new material for removing ammonium from synthetic water (ammonium concentration from 10 to 100 mg/L). The characteristics of the modified biochar were determined by Brunauer-Emmett-Teller (BET) test, Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). It was found that ammonium adsorption on modified biochar strongly depended on pH. Adsorption kinetics of NH4+-N using modified biochar followed the pseudo-second order kinetic model. Both Langmuir and Sips adsorption isotherm models could simulate well the adsorption behavior of ammonium on modificated biochar. The highest adsorption capacity of 22.6 mg NH4+-N/g modified biochar was obtained when the biochar was modified by soaking it in HNO3 6 M and NaOH 0.3 M for 8 h and 24 h, respectively. The high adsorption capacity of the modified biochar suggested that it is a promising adsorbent for NH4+-N remediation from water
Vu, T.M., Trinh, V.T., Doan, D.P., Van, H.T., Nguyen, T.V., Vigneswaran, S. & Ngo, H.H. 2017, 'Removing ammonium from water using modified corncob-biochar', Science of the Total Environment, vol. 579, pp. 612-619.
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Ammonium pollution in groundwater and surface water is of major concern in many parts of the world due to the danger it poses to the environment and people's health. This study focuses on the development of a low cost adsorbent, specifically a modified biochar prepared from corncob. Evaluated here is the efficiency of this new material for removing ammonium from synthetic water (ammonium concentration from 10 to 100 mg/L). The characteristics of the modified biochar were determined by Brunauer-Emmett-Teller (BET) test, Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). It was found that ammonium adsorption on modified biochar strongly depended on pH. Adsorption kinetics of NH4+-N using modified biochar followed the pseudo-second order kinetic model. Both Langmuir and Sips adsorption isotherm models could simulate well the adsorption behavior of ammonium on modificated biochar. The highest adsorption capacity of 22.6 mg NH4+-N/g modified biochar was obtained when the biochar was modified by soaking it in HNO3 6 M and NaOH 0.3 M for 8 h and 24 h, respectively. The high adsorption capacity of the modified biochar suggested that it is a promising adsorbent for NH4+-N remediation from water
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.
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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&copy; 2017 Elsevier LtdConstructed wetlands (CWs) have been used as a green technology to treat various wastewaters for several decades, and greenhouse gases production in these systems attracted increasing attention considering the contributions of methane and nitrous oxide emissions to global warming. However, the detailed knowledge about the contribution of CWs to methane and nitrous oxide emissions in treating sewage treatment plant effluent are still limited in particular for a better understanding of the sustainability of CWs. The fluxes of methane (CH4) and nitrous oxide (N2O) from free water surface (FWS) CWs in northern China were measured continuously using the static-stationary chamber technique from 2012 to 2013. The results showed that CWs were the significant source of CH4 and N2O emissions. Average emission rates of CH4 and N2O ranged from 30.2 g m2 h1 to 450.9 g m2 h1, and -58.8 g m2 h1 to 1251.8 g m2 h1, respectively. Obvious annual and seasonal variations of CH4 and N2O emissions were observed over the 2-year period. In addition, temperatures and plant species had an impact on CH4 and N2O emissions. The obtained results showed that FWS CWs, improving water quality but emitting lower CH4 and N2O, could be the alternative method for sewage treatment plant effluent.
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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&copy; 2017 Elsevier B.V.Membrane fouling is the most serious challenge in the hollow fiber microfiltration (MF) and ultrafiltration (UF) processes. A number of in-situ monitoring techniques including optical and non-optical probes have been developed so that membrane fouling is better understood and controlled. This will help advance the membrane technology. In addition, the local filtration hydrodynamics wield a great influence on the membrane fouling formation and system operation stability. State-of-the-art in-situ monitoring techniques for membrane fouling and local filtration characteristics in hollow fiber MF/UF processes are critically reviewed. The principles and applications of these techniques are addressed in order to assess their strengths. This study demonstrated that the real-time observation techniques mainly focus on idealized laboratory apparatus and little on commercial membrane modules. Consequently, more attention should be paid to the development of simple and effective methods or integrated detecting technology so as to satisfy the real status of hollow fiber filtration processes and the optimization of membrane module. On the basis of this review, future analyses considering practical requirements are suggested as R&D priorities.
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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&copy; 2016 Elsevier B.V.A novel microbial fuel cell (MFC) was developed to enhance simultaneous nitrification and denitrification (SND) by employing electrons from the anode. The cathode chamber of the reactor consisted of a membrane aerated biofilm reactor (MABR) which was made of an electroconductivity aerated membrane. The maximum power density of 4.20 &plusmn; 0.12 W m3 was obtained at a current density of 4.10 &plusmn; 0.11 A m2 (external resistance = 10 ). Compared with an open-circuit system, the removal rates of NH4+-N and TN were improved by 9.48 &plusmn; 0.33% and 19.80 &plusmn; 0.84%, respectively, which could be ascribed to the electrochemical denitrification. The anode (chemical oxygen demand, COD) and cathode (NO3) chambers reached the maximum coulombic efficiencies (CEs) of 40.67 &plusmn; 1.05% and 42.84 &plusmn; 1.14%, respectively. It suggested that the electroconductivity MABR has some advantages in controlling aeration intensity, thus improving SND and CEs. Overall, EAM-MFC could successfully generate electricity from wastewater whilst showing high capacity for removing nitrogen at a low COD/N ratio of 2.8 &plusmn; 0.07 g COD g1 N.
Nguyen, D.D., Chang, S.W., Cha, J.H., Jeong, S.Y., Yoon, Y.S., Lee, S.J., Tran, M.C. & Ngo, H.H. 2017, 'Dry semi-continuous anaerobic digestion of food waste in the mesophilic and thermophilic modes: New aspects of sustainable management and energy recovery in South Korea', Energy Conversion and Management, vol. 135, pp. 445-452.
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&copy; 2016 Elsevier LtdIn this study, parallel, bench-scale, mesophilic and thermophilic, dry, semi-continuous anaerobic digestion (DScAD) of Korea food waste (FW, containing 22% total solids (TS) and 20% volatile solids (VS)) was investigated thoroughly under varying operational conditions, including hydraulic retention times (HRTs) and organic loading rates (OLRs). The aim was to evaluate the start-up, stability, overall removal efficiency, and inhibitory effects of toxic compounds on process performance over a long-term operation lasting 100 days. The results from both digesters indicate that the simultaneous reduction of VS and the production of gas improved as the HRT decreased or the OLR increased. The highest average rates of VS reduction (79.67%) and biogas production (162.14 m3 biogas/ton of FW, 61.89% CH4), at an OLR of 8.62 &plusmn; 0.34 kg VS/m3 day (25 days of HRT), were achieved under thermophilic DScAD. In addition, the average rates of reduction of VS and the production of biogas in thermophilic DScAD were higher by 6.88% and 16.4%, respectively, than were those in mesophilic DScAD. The inhibitory effects of ammonia, H2S, and volatile fatty acids (VFAs) on methane production was not clear from either of the digesters, although, apparently, their concentrations did fluctuate. This fluctuation could be attributed to the self-adaptation of the microbial well. However, digestion that was more stable and faster was observed under thermophilic conditions compared with that under mesophilic conditions. Based on our results, the optimum operational parameters to improve FW treatment and achieve higher energy yields could be determined, expanding the application of DScAD in treating organic wastes.
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.
Jin, P., Wang, X., Zhang, Q., Wang, X., Ngo, H.H. & Yang, L. 2016, 'A new activated primary tank developed for recovering carbon source and its application.', Bioresource technology, vol. 200, pp. 722-730.
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A novel activated primary tank process (APT) was developed for recovering carbon source by fermentation and elutriation of primary sludge. The effects of solids retention time (SRT), elutriation intensity (G) and return sludge ratio (RSR) on this recovery were evaluated in a pilot scale reactor. Results indicated that SRT significantly influenced carbon source recovery, and mechanical elutriation could promote soluble COD (SCOD) and VFA yields. The optimal conditions of APT were SRT=5d, G=152s(-1) and RSR=10%, SCOD and VFA production were 57.0mg/L and 21.7mg/L. Particulate organic matter in sludge was converted into SCOD and VFAs as fermentative bacteria were significantly enriched in APT. Moreover, the APT process was applied in a wastewater treatment plant to solve the problem of insufficient carbon source. The outcomes demonstrated that influent SCOD of biological tank increased by 31.1%, which improved the efficiency of removing nitrogen and phosphorus.
Hu, Y., Wang, X.C., Tian, W., Ngo, H.H. & Chen, R. 2016, 'Towards stable operation of a dynamic membrane bioreactor (DMBR): Operational process, behavior and retention effect of dynamic membrane', Journal of Membrane Science, vol. 498, pp. 20-29.
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&copy; 2015 Elsevier B.V. An experimental study was conducted for characterizing the whole operational cycle of a dynamic membrane bioreactor (DMBR). With a nylon mesh of 25. m pore size as support material, the filtration flux was suddenly halved within 5 min, indicating a rapid cake layer formation. Then the flux declined gradually and became stable at t=4. h, indicating the maturation of the dynamic membrane (DM) for stable operation. By periodical bottom aeration, the flux kept stable until t=24. h before physical cleaning should be conducted for DM regeneration. In such an operational cycle, effluent turbidity about 3. NTU was only detected at the start, dropped to about 0.5. NTU after 5 min and kept lower afterwards. Effective and stable removal of chemical oxygen demand (COD), ammonia, phosphorus was achieved in the 2-month continuous operation period. Although air backwashing brought about effective recovery of the flux, additional surface brushing could further remove the "irremovable fouling". By morphological and physicochemical analysis, it was identified that the DM could retain 15.3% of COD and 10.6% of polysaccharides from the activated sludge, as well as certain amount of protein-like and humic-like substances. These membrane fouling substances should be removed by physical cleaning for DM regeneration.
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.
Hu, L., Yang, Z., Cui, L., Li, Y., Ngo, H.H., Wang, Y., Wei, Q., Ma, H., Yan, L. & Du, B. 2016, 'Fabrication of hyperbranched polyamine functionalized graphene for high-efficiency removal of Pb(II) and methylene blue', Chemical Engineering Journal, vol. 287, pp. 545-556.
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&copy; 2015 Elsevier B.V. Multifunctional hyperbranched polyamine modified graphene oxide (HPA-GO) was successfully prepared and characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), zeta potential and scanning electron microscope (SEM) analyses. HPA-GO exhibited excellent adsorption performance for the removal of a heavy metal (Pb(II)) and a dye (methylene blue (MB)). The equilibrium adsorption capacity was 819.7 mg g-1 for Pb(II) and 740.7 mg g-1 for MB under the optimal conditions. The pseudo-second order equation and the Langmuir model exhibited good correlation with the adsorption kinetic and isotherm data, respectively, for these two pollutants. The thermodynamic results (G<0, H>0, S>0) implied that the adsorption process of Pb(II) and MB was feasible, endothermic and spontaneous in nature. A possible adsorption mechanism has been proposed where chelation and electrostatic attraction dominated the adsorption of Pb(II) and - stacking interactions and electrostatic attraction dominated the adsorption of MB. In addition, the excellent reproducibility endowed HPA-GO with the potential for application in water treatment.
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.
Gao, T., Chen, R., Wang, X., Ngo, H.H., Li, Y.Y., Zhou, J. & Zhang, L. 2016, 'Application of disease burden to quantitative assessment of health hazards for a decentralized water reuse system.', The Science of the total environment, vol. 551-552, pp. 83-91.
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The aim of this article is to introduce the methodology of disease burden (DB) to quantify the health impact of microbial regrowth during wastewater reuse, using the case study of a decentralized water reuse system in Xi'an Si-yuan University, located in Xi'an, China. Based on field investigation findings, Escherichia coli (E. coli), Salmonella and rotavirus were selected as typical regrowth pathogens causing potential health hazards during the reuse of reclaimed water. Subsequently, major exposure routes including sprinkler irrigation, landscape fountains and toilet flushing were identified. Mathematical models were established to build the relationship between exposure dose and disease burden by calculating the disability adjusted life year (DALY). Results of disease burden for this case study show that DALYs attributed to E. coli were significantly greater than those caused by other pathogens, and DALYs associated with sprinkler irrigation were higher than those originating from other routes. A correlation between exposure dose and disease was obtained by introducing a modified calculation of morbidity, which can extend the assessment endpoint of health risk to disease burden from the conventional infection rate.
Nguyen, D.D., Ngo, H.H. & Yoon, Y.S. 2016, 'Effect of internal recycling ratios on biomass parameters and simultaneous reduction of nitrogen and organic matter in a hybrid treatment system', Ecological Engineering, vol. 89, pp. 24-31.
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&copy; 2016 Elsevier B.V. A new large-scale pilot hybrid treatment system of 53 m3/day was developed by combining 3 treatment methods: switched internal recycling flows to equalization tank (EQ); rotating hanging media bioreactor (RHMBR); and submerged flat sheet membrane bioreactor (SMBR). The system was operated for more than 16 months in a real-world municipal wastewater treatment plant, using different internal recycling ratios and observing/monitoring the results. This paper addresses not only the urgent problems of treating nutrient and organic pollutants in municipal wastewater, but also assesses characteristics of biomass production, sludge yield, and observed yield during the pilot operation. It also details design parameters used to achieve these assessed levels. Furthermore, the effects and correlations of the loading rates, activated sludge and biomass parameters, on different runs were also studied. The purpose of this was to identify the most suitable indicator for assessing the hybrid system's performance. Results strongly indicated that increasing the internal circulation rate greatly influenced the declining yield trend. The lowest biomass production (Px,bio) and sludge yields (PX,VSS or PX,TSS) were shown for conditions in run 3, and run 4, respectively. Overall the developed treatment system performed extremely well in biological terms for actual municipal wastewater treatment and resulted in high pollutant removal efficiencies, reduced sludge production at a reasonable cost. The hybrid system is a potential option for wastewater treatment, reuse and economy.
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.
Hu, Y., Wang, X.C., Yu, Z., Ngo, H.H., Sun, Q. & Zhang, Q. 2016, 'New insight into fouling behavior and foulants accumulation property of cake sludge in a full-scale membrane bioreactor', Journal of Membrane Science, vol. 510, pp. 10-17.
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&copy; 2016 Elsevier B.V.. Cake sludge attached on membrane surfaces was collected and characterized in a full scale membrane bioreactor (MBR) compared with bulk sludge. The morphological, chemical and microbial properties were examined through microscopic observations, particle size distribution (PSD) analysis, chemical analysis, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy-diffusive X-ray (EDX) analysis, specific oxygen utilization rate (SOUR) measurements and Biolog assay. The results showed that fiber-like substances might have served as the skeleton of larger size aggregates in cake sludge. Moreover, much more polysaccharides and inorganic elements such as multivalent cations were accumulated in cake sludge than proteins and humics. Cake sludge showed lower microbial activity for aerobic degradation than bulk sludge, but higher metabolic activity for the degradation of refractory substances (aromatic proteins and humics) other than polysaccharides. Based on batch filtration experiments, it was found that cake sludge had much higher cake layer fouling potential but lower membrane pore blocking resistance, probably due to the heterogeneous structure of cake sludge resulting from accumulation and interaction of various inorganic and organic foulants. This investigation could assist in obtaining a better understanding of the fouling behavior and foulants accumulation properties of cake sludge in the full-scale MBRs.
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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&copy; 2016 Elsevier B.V. All rights reserved. The performance and membrane fouling of a lab-scale submerged sponge-membrane bioreactor (Sponge-MBR) and a conventional MBR were investigated and compared for hospital wastewater treatment at low fluxes of 2-6 LMH. COD removal by the Sponge-MBR was similar to that of the MBR, while the Sponge-MBR achieved 9-16% removed more total nitrogen than the MBR. This was due to 60% of total biomass being entrapped in the sponges, which enhanced simultaneous nitrification denitrification. Additionally, the fouling rates of the Sponge-MBR were 11-, 6.2- and 3.8-times less than those of the MBR at flux rates of 2, 4 and 6 LMH, respectively. It indicates the addition of sponge media into a MBR could effectively reduce the fouling caused by cake formation and absorption of soluble substances in a low flux scenario.
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.
Zhou, S., Huang, T., Ngo, H.H., Zhang, H., Liu, F., Zeng, M., Shi, J. & Qiu, X. 2016, 'Nitrogen removal characteristics of indigenous aerobic denitrifiers and changes in the microbial community of a reservoir enclosure system via in situ oxygen enhancement using water lifting and aeration technology.', Bioresource technology, vol. 214, pp. 63-73.
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Indigenous aerobic denitrifiers of a reservoir system were enhanced in situ by water lifting and aeration technology. Nitrogen removal characteristics and changes in the bacterial community were investigated. Results from a 30-day experiment showed that the TN in the enhanced water system decreased from 1.08-2.02 to 0.75-0.91mg/L and that TN removal rates varied between 21.74% and 52.54% without nitrite accumulation, and TN removal rate of surface sediments reached 41.37&plusmn;1.55%. The densities of aerobic denitrifiers in the enhanced system increased. Furthermore, the enhanced system showed a clear inhibition of Fe, Mn, and P performances. Community analysis using Miseq showed that diversity was higher in the in situ oxygen enhanced system than in the control system. In addition, the microbial composition was significantly different between systems. It can be concluded that in situ enhancement of indigenous aerobic denitrifiers is very effective in removing nitrogen from water reservoir systems.
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.
Kalaruban, M., Loganathan, P., Shim, W.G., Kandasamy, J., Ngo, H.H. & Vigneswaran, S. 2016, 'Enhanced removal of nitrate from water using amine-grafted agricultural wastes', SCIENCE OF THE TOTAL ENVIRONMENT, vol. 565, pp. 503-510.
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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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&copy; 2016 Elsevier B.V.Poor stability of land/water ecotone (L/WE) soil is a serious and increasing problem in the context of ecological restoration. Effective management by adding straw and polyacrylamide (PAM), i.e., SPAM, to soil may increase soil stability, including structure and fertility. Thus, it is important to explore the effects of SPAM on L/WE soil, as well as to determine the appropriate ratio of straw and PAM to achieve optimal increases. To investigate the soil properties and provide basis for ecological restoration, an indoor soil culture experiment, including nine straw and PAM combinations, was conducted. It was found that 3 g/kg straw with 1 g/kg PAM was optimal; thus, this scale was applied in engineering of Gonghu L/WE, which was turning Fishery to Lake. The survey explored changes in soil nutrients and structure, dry-sieved aggregate stability, and wet-sieved water aggregate stability under nine measures. Results indicated that the measurement of SPAM strongly affected soil properties, such as improvements in the fine sand and clay fraction, decreased coarse sand fraction and density, and enhanced content of the larger aggregates (>2 mm), organic matter (OM), availabl. e nitrogen (AN), available phosphorus (AP), and available potassium (AK). For soil nutrients, applying of Straw/PAM significantly improved the contents of OM/AN, respectively; showing an increasing trend with a dosage rate. Meanwhile, it was shown that SPAM was more effective than treating each individual component on AP and AK improvements. Regarding soil structure, application of PAM significantly increased contents of the dry-sieved aggregates and wet-sieved water-stable aggregates, especially aggregates >2 mm. Straw mulching only improved the content of dry-sieve medium size aggregates. However, when combining SPAM, the straw improved the medium particle size fraction, after which PAM converted a portion of the medium particles into >2.0 mm aggregates. Furthermore, the measur...
Zhang, Q.Y., Ma, X.Y., Wang, X.C. & Ngo, H.H. 2016, 'Assessment of multiple hormone activities of a UV-filter (octocrylene) in zebrafish (Danio rerio).', Chemosphere, vol. 159, pp. 433-441.
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In this study, zebrafish (Danio rerio) were exposed to a UV-filter-octocrylene (OCT) with elevated concentrations for 28&nbsp;d. The total body accumulation of OCT in zebrafish was found to reach 2321.01 ("L" level), 31,234.80 ("M" level), and 70,593.38&nbsp;ng&nbsp;g(-1) ("H" level) when the average OCT exposure concentration was controlled at 28.61, 505.62, and 1248.70&nbsp;g&nbsp;L(-1), respectively. Gross and histological observations as well as RT-qPCR analysis were conducted to determine the effects of OCT accumulation on zebrafish. After exposure, the gonad-somatic index and percentage of vitellogenic oocytes were found to increase significantly in the ovaries of female zebrafish at the H accumulation level. Significant up-regulation of esr1 and cyp19b were observed in the gonads, as well as vtg1 in the livers for both female and male zebrafish. At M and H accumulation levels, apparent down-regulation of ar was observed in the ovaries and testis of the female and male zebrafish, respectively. Although the extent of the effects on zebrafish differed at different accumulation levels, the induction of vtg1 and histological changes in the ovaries are indications of estrogenic activity and the inhibition of esr1 and ar showed antiestrogenic and antiandrogenic activity, respectively. Thus, as OCT could easily accumulate in aquatic life such as zebrafish, one of its most of concern hazards would be the disturbance of the histological development and its multiple hormonal activities.
Tran, N.H., Chen, H., Do, T.V., Reinhard, M., Ngo, H.H., He, Y. & Gin, K.Y. 2016, 'Simultaneous analysis of multiple classes of antimicrobials in environmental water samples using SPE coupled with UHPLC-ESI-MS/MS and isotope dilution.', Talanta, vol. 159, pp. 163-173.
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A robust and sensitive analytical method was developed for the simultaneous analysis of 21 target antimicrobials in different environmental water samples. Both single SPE and tandem SPE cartridge systems were investigated to simultaneously extract multiple classes of antimicrobials. Experimental results showed that good extraction efficiencies (84.5-105.6%) were observed for the vast majority of the target analytes when extraction was performed using the tandem SPE cartridge (SB+HR-X) system under an extraction pH of 3.0. HPLC-MS/MS parameters were optimized for simultaneous analysis of all the target analytes in a single injection. Quantification of target antimicrobials in water samples was accomplished using 15 isotopically labeled internal standards (ILISs), which allowed the efficient compensation of the losses of target analytes during sample preparation and correction of matrix effects during UHPLC-MS/MS as well as instrument fluctuations in MS/MS signal intensity. Method quantification limit (MQL) for most target analytes based on SPE was below 5ng/L for surface waters, 10ng/L for treated wastewater effluents, and 15ng/L for raw wastewater. The method was successfully applied to detect and quantify the occurrence of the target analytes in raw influent, treated effluent and surface water samples.
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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&copy; 2016 Elsevier B.V.Recent discovery of ammonia-oxidizing archaea (AOA) not only substantially improved our understanding of the global nitrogen cycle, but also provided new possibilities for nitrogen removal from wastewater. In particular, compared to ammonia-oxidizing bacteria (AOB), the high ammonia oxidation under oxygen-limited conditions driven by AOA is potentially more suitable for autotrophic nitrogen removal in a single-stage membrane aerated biofilm reactor (MABR) through coupling with anaerobic ammonia oxidation (Anammox). In this work, mathematical modeling is applied to assess the system performance and associated microbial community structure of an AOA&#8211;Anammox MABR under low- (30&nbsp;mg&nbsp;N&nbsp;L1) and high-strength (500&nbsp;mg&nbsp;N&nbsp;L1) ammonium conditions, with a side-by-side comparison to an AOB&#8211;Anammox MABR system under the same conditions. Results demonstrate that both ammonium surface loading (or hydraulic retention time) and oxygen surface loading significantly affect the system performance. In contrast to AOB&#8211;Anammox system, the AOA&#8211;Anammox MABR shows higher total nitrogen (TN) removal and lower oxygen supply, with much better repression of NOB and substantially wider operating window for high-level TN removal (>80%) in terms of varied oxygen and ammonium loadings. These results provide first insights and useful information for design and operation of this novel AOA&#8211;Anammox MABR system in its potential future applications.
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.
To, V.H.P., Nguyen, T.V., Vigneswaran, S. & Ngo, H.H. 2016, 'A review on sludge dewatering indices.', Water science and technology : a journal of the International Association on Water Pollution Research, vol. 74, no. 1, pp. 1-16.
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Dewatering of sludge from sewage treatment plants is proving to be a significant challenge due to the large amounts of residual sludges generated annually. In recent years, research and development have focused on improving the dewatering process in order to reduce subsequent costs of sludge management and transport. To achieve this goal, it is necessary to establish reliable indices that reflect the efficiency of sludge dewatering. However, the evaluation of sludge dewaterability is not an easy task due to the highly complex nature of sewage sludge and variations in solid-liquid separation methods. Most traditional dewatering indices fail to predict the maximum cake solids content achievable during full-scale dewatering. This paper reviews the difficulties in assessing sludge dewatering performance, and the main techniques used to evaluate dewatering performance are compared and discussed in detail. Finally, the paper suggests a new dewatering index, namely the modified centrifugal index, which is demonstrated to be an appropriate indicator for estimating the final cake solids content as well as simulating the prototype dewatering process.
Ma, X.Y., Wang, X.C., Wang, D., Ngo, H.H., Zhang, Q., Wang, Y. & Dai, D. 2016, 'Function of a landscape lake in the reduction of biotoxicity related to trace organic chemicals from reclaimed water.', Journal of hazardous materials, vol. 318, pp. 663-670.
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The storage of water in a landscape lake can act as a buffer zone between reclaimed water production and reuse, but there is still uncertainty about the variation of water quality and toxic effects during the open-storage process. In this study, long-term sample collection, chemical analyses and biotoxicity assessments were conducted on reclaimed water before and after open storage in a landscape lake. The organic contents, in terms of chemical oxygen demand and total organic carbon, were found to be slightly higher in the lake water than that in the reclaimed water, but substantial reduction of the total concentration of 52 trace organic chemicals was obtained and microorganism toxicity, phytotoxicity, aquatic vertebrate toxicity and genotoxicity, were significantly weakened after open storage. Furthermore, the total risk quotient (RQTotal) decreased from 5.12 (potential ecological risk level) in the reclaimed water to 0.18 (negligible ecological risk level) in the lake water. The removal of chlorpyrifos, dichlorphos and tetracycline was identified as the main reason for biotoxicity reduction after open storage. The seminatural environment of the landscape lake would have provided a favorable condition for the decay of toxic trace organic chemicals so that the stored water turned to be safer for further reuse.
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.
Nguyen, D.D., Ngo, H.H., Yoon, Y.S., Chang, S.W. & Bui, H.H. 2016, 'A new approach involving a multi transducer ultrasonic system for cleaning turbine engines' oil filters under practical conditions.', Ultrasonics, vol. 71, pp. 256-263.
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The purpose of this paper is to provide a green technology that can clean turbine engine oil filters effectively in ships using ultrasound, with ultrasonic devices having a frequency of 25kHz and different powers of 300W and 600W, respectively. The effects of temperature, ultrasonic cleaning times, pressure losses through the oil filter, solvent washing, and ultrasonic power devices were investigated. In addition, the cleaning efficiency of three modes (hand washing, preliminary washing and ultrasonic washing) were compared to assess their relative effectiveness. Experimental results revealed that the necessary ultrasonic time varied significantly depending on which solvent was used for washing. For instance, the optimum ultrasonic cleaning time was 50-60min when the oil filter was cleaned in a solvent of kerosene oil (KO) and over 80min when in a solvent of diesel oil (DO) using the same ultrasonic generator device (25kHz, 600W) and experimental conditions. Furthermore, microscopic examination did not reveal any damage or breakdown on or within the structure of the filter after ultrasonic cleaning, even in the filter's surfaces at a constantly low frequency of 25kHz and power specific capacity (100W/gal). Overall, it may be concluded that ultrasound-assisted oil filter washing is effective, requiring a significantly shorter time than manual washing. This ultrasonic method also shows promise as a green technology for washing oil filters in turbine engines in general and Vietnamese navy ships in particular, because of its high cleaning efficiency, operational simplicity and savings.
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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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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&copy; 2016 Elsevier B.V.This study investigated the rapid start-up of an anaerobic ammonium oxidation (anammox) reactor by inoculating denitrifying granular sludge mixed anammox bacteria. The mechanism of the anammox electron transport chain (AETC) was also studied using nine different inhibitors in batch tests. This is the first study that shortened the start-up anammox reactor time to 28 days. Nitrogen removal rates (NRRs) up to 0.72 kg/(m3 d) on day 28 were achieved. Each studied inhibitor had a different binding site in the AETC. The effect of each inhibitor was determined by comparing the total nitrogen removal efficiency between the presence of an inhibitor and an appropriate control. The results confirmed that each inhibitor had various inhibition degrees that distinctly affected the AETC. Finally, the AETC mechanism was explored in detail. These findings are important for developing fast start-up processes for anammox reactors.
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.
Le Thi Minh, T., Nguyen Phuoc, D., Dinh Quoc, T., Ngo, H.H. & Do Hong Lan, C. 2016, 'Presence of e-EDCs in surface water and effluents of pollution sources in Sai Gon and Dong Nai river basin', Sustainable Environment Research, vol. 26, no. 1, pp. 20-27.
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&copy; 2016This study aimed to assess the presence of estrogenic endocrine disrupting compounds (e-EDCs) including estriol, bisphenol A (BPA), atrazine (ATZ), octylphenol, octylphenol diethoxylate, octylphenol triethoxylate, nonylphenol, Nonylphenol triethoxylate (NPE3), nonylphenol diethoxylate (NPE2) and 17-estradiol in: (i) Sai Gon and Dong Nai river waters which have been major raw water sources for drinking water supply for Ho Chi Minh City (HCMC) and neighbouring provinces, and (ii) water pollution sources located in their catchment basin. NPE3 and NPE2 were detected in most of the surface water samples. Concentrations of NPE3 were in a range of less than 5.9&#8211;235&nbsp;ng&nbsp;L1, whereas BPA was detected at significantly high concentrations in the dry season in canals in HCMC. In the upstream of Sai Gon and Dong Nai Rivers, ATZ concentrations were observed at water intake of water treatment plants served for HCMC water supply system. Similarly, high potential risk of NPE2 and NPE3 contamination at Phu Cuong Bridge near Hoa Phu water intake was identified. The significant correlation between NPE2, dissolved organic carbon and total nitrogen was found. Estrogenic equivalent or estrogenic activity of Sai Gon and Dong Nai Rivers was lower than those of the previous studies. Compared with other studies, e-EDCs of pollution in Sai Gon river basin were relatively low.
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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&copy; 2016 The Royal Society of Chemistry.This work investigated the impact of gas slug flow on microfiltration in an airlift external loop tubular membrane reactor. A complete description for the characteristics of the slug flow was obtained as the aeration rate increased from 30 to 120 L h-1 with an interval of 30 L h-1. The shear stress of the falling film region could reach 6.37 10-3 Pa with the aeration rate of 90 L h-1. Experimental results showed that the growth of transmembrane pressure (TMP) could be controlled effectively by increasing the aeration rate and the optimal aeration rate in a slug flow was around 90 L h-1. However, a subsequent increase in the aeration rate had no significant effect on slowing down the TMP growth rate. Turning the constant air-flow into periodic pulsatile air-flow, low gas-velocity and high gas-velocity led to alternate operation in filtration. When the alternate interval of pulsatile air-flow was 60 s at the alternate aeration rates of 30/90 L h-1 and 60/90 L h-1, it could delay membrane fouling and save a lot of gas compared with implementing a constant air-flow of 90 L h-1. Finally, for different water outlet positions along the membrane tube, membrane fouling gradually slowed down from the bottom to the top.
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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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. 2016, 'Enhanced efficiency for better wastewater sludge hydrolysis conversion through ultrasonic hydrolytic pretreatment', Journal of the Taiwan Institute of Chemical Engineers.
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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.
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. 2016, '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.
Hu, J., Zhang, Q., Lee, D.J. & Ngo, H.H. 2016, 'Feasible use of microbial fuel cells for pollution treatment', Renewable Energy.
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&copy; 2017 Elsevier Ltd.The microbial fuel cells (MFC) can directly transform chemical energy in feed substance to electricity by anodic aspiration pathways. This mini review provides an order-of-magnitude argument that MFC has much lower catalyst density at electrode surface and much higher diffusional resistance for substrates than the chemical fuel cell, the former should not be used as an energy generation unit; rather, it should be applied in low power density level applications such as biofilm wastewater treatment. The literature studies using MFC for pollution treatment are discussed.
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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&copy; 2015 Elsevier B.V. Ultrasonic time domain reflectometry (UTDR) was used to monitor the deposition of combined organic-colloidal fouling on a nanofiltration membrane. The fouling experiments were performed with different feed solutions: a mixture of 1000. mg/L silica and 1000. mg/L NaCl, a mixture of 1000. mg/L silica and 250. mg/L BSA, and 250. mg/L BSA alone, respectively. Results showed that the rate of flux decline obtained in the constant-pressure experiment with the mixture of silica. +. BSA was greater than that with the mixture of silica. +. NaCl and BSA alone. The acoustic measurements indicated that the fouling layer obtained from the combined organic-colloidal fouling was denser than that obtained from the colloidal fouling layer in the presence of NaCl. Furthermore, the mixed foulants rapidly deposited on the membrane surface in the early fouling phase, and then reached a plateau in the later fouling phase under a constant pressure operation, whereas the mixed foulants gradually deposited on the membrane surface as the fouling progressed under a constant flux operation. The main reason for the rapid foulant deposition during the initial fouling stage under constant pressure operation was because the initial flux was above the critical flux. The off-line AFM analysis and zeta potential measurements corroborated the ultrasonic measurements.
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.
Ni, S.Q., Sun, N., Yang, H., Zhang, J. & Ngo, H.H. 2015, 'Distribution of extracellular polymeric substances in anammox granules and their important roles during anammox granulation', Biochemical Engineering Journal, vol. 101, pp. 126-133.
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&copy; 2015 Elsevier B.V. Extracellular matrix plays a significant role in formation of matrix structure, biogranulation process and improvement of stability of anammox granules. Distributions of cells and extracellular polymeric substances (EPS) in anammox granules cultured from activated sludge and inactive methanogenic granules were probed. Anammox bacteria secreted more EPS than anaerobic/aerobic granules. The layer of EPS surrounding anammox cells was thicker than other types of granules. In high-enriched granules, the proteins and -. d-glucopyranose polysaccharides were principally distributed at the core, whereas the cells and -. d-glucopyranose polysaccharide accumulated in both the interior and outer layers of granules. In low-enriched ones, cells and -. d-glucopyranose polysaccharides were mainly distributed at the outer rim and the -. d-glucopyranose polysaccharides were located in both the core and the outer layer, whilst the proteins were distributed throughout the whole structure of granules. EPS distribution indicated that low-enriched granules possessed higher stability than high-enriched ones, in consistent with granule strength test.
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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&copy; The Royal Society of Chemistry. The feasibility of preparing activated carbon (AC-CHs) from carbohydrates (glucose, sucrose and starch) with phosphoric acid activation was evaluated by comparing its physicochemical properties and Ni(ii) adsorption performance with a reference activated carbon (AC-PA) derived from Phragmites australis. The textural and chemical properties of the prepared activated carbon were characterized by N<inf>2</inf> adsorption/desorption isotherms, SEM, Boehm's titration and XPS. Although AC-CHs had much lower surface area (less than 700 m<sup>2</sup> g<sup>-1</sup>) than AC-PA (1057 m<sup>2</sup> g<sup>-1</sup>), they exhibited 45-70% larger Ni(ii) adsorption capacity which could be mainly attributed to their 50-75% higher contents of total acidic and basic groups. The comparison of XPS analyses for starch-based activated carbon before and after Ni(ii) adsorption indicated that Ni(ii) cation combined with the oxygen-containing groups and basic groups (delocalized -electrons) through the mechanisms of proton exchange, electrostatic attraction, and surface complexation. Kinetic results suggested that chemical reaction was the main rate-controlling step, and a very quick Ni(ii) adsorption performance of AC-CHs was presented with 95% of maximum adsorption within 30 min. Both adsorption capacity and rate of the activated carbon depended on the surface chemistry as revealed by batch adsorption experiments and XPS analyses. This study demonstrated that AC-CHs could be promising materials for Ni(ii) pollution minimization.
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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&copy; 2015 American Institute of Chemical Engineers. A filtration mathematical model was developed on the basis of complete mass balance and momentum balance for the local flux distribution prediction and optimization of submerged hollow fiber membrane module. In this model, the effect of radial permeate flow on internal flow resistance was considered through a slip parameter obtained from the local flux experiments. The effects of fiber length, inside diameter, and average operating flux on local flux distribution were investigated using this model. The predicted results were in good agreement with the experimental data obtained from literature. It was also found that the asymmetry distribution of local flux could be intensified with the increase of average operating flux and fiber length, but slowed down with the increase of fiber inside diameter. Furthermore, the simulation coupled with energy consumption analysis could efficiently predict and illustrate the relationship between fiber geometry and water production efficiency.
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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Tran, N.H., Ngo, H.H., Urase, T. & Gin, K.Y.-.H. 2015, 'A critical review on characterization strategies of organic matter for wastewater and water treatment processes', Bioresource Technology, vol. 193, pp. 523-533.
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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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&copy; 2015 The Royal Society of Chemistry. To reduce operating costs and membrane fouling of conventional membrane bioreactors (cMBR), a novel MBR using a non-woven fabric membrane (nMBR) was constructed and the performance of the two MBRs was compared for anaerobic ammonium oxidation (anammox) cultivation. The results showed that the start-up period for the nMBR (44 days) was notably shorter than that for the cMBR (56 days), meanwhile the nMBR achieved a 2-times higher nitrogen removal rate (231.5 mg N per L per d) compared to the cMBR (112.3 mg N per L per d). Illumina MiSeq sequencing showed that Candidatus Kuenenia and Candidatus Jettenia were the main distinguished anammox bacteria. FISH analysis revealed that anammox bacteria predominated in both reactors, especially in the nMBR (58%) corresponding to a qPCR analysis of 1.07 109 copies per mL (day 120). N2O emission analysis confirmed the advantage of the nMBR in N2O reduction to reduce the influence of greenhouse gas emission while treating identical nitrogen. These results clearly demonstrated that nMBRs could be a prospective choice for anammox start-up and performance enhancement.
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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&copy; 2015 The Royal Society of Chemistry. Five different types of activated carbon varying in porosity, structure, and functional groups were prepared and used as adsorbents. The effect of the key properties of each activated carbon on its adsorption capacity, rate and mechanisms on trimethoprim (TMP) removal were evaluated. The kinetics results suggested that chemical adsorption interactions and particle diffusion into micropores were the main rate-control steps for TMP adsorption, and the existence of mesopores promoted the diffusion of TMP into internal pores. The adsorption of TMP onto activated carbon can be attributed to the pore-filling effect (micropores and some narrow mesopores) and strong adsorptive interactions with the graphene surface or oxygenated groups. Regarding the surface area-normalized adsorption of TMP, porous activated carbon exhibited 50-500 times lower adsorption than nonporous carbon adsorbent due to the size-exclusion effect, especially when oxygen complexes presented on the edges of the pores of the activated carbon. From a system design point of view, a fast adsorption rate and high adsorption capacity are normally required, and these findings imply that activated carbon with high microporosity, a certain mesoporosity and approachable surface groups can have great application potential for TMP removal.
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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Tran, N.H., Gin, K.Y.-.H. & Ngo, H.H. 2015, 'Fecal pollution source tracking toolbox for identification, evaluation and characterization of fecal contamination in receiving urban surface waters and groundwater.', Sci Total Environ, vol. 538, pp. 38-57.
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The quality of surface waters/groundwater of a geographical region can be affected by anthropogenic activities, land use patterns and fecal pollution sources from humans and animals. Therefore, the development of an efficient fecal pollution source tracking toolbox for identifying the origin of the fecal pollution sources in surface waters/groundwater is especially helpful for improving management efforts and remediation actions of water resources in a more cost-effective and efficient manner. This review summarizes the updated knowledge on the use of fecal pollution source tracking markers for detecting, evaluating and characterizing fecal pollution sources in receiving surface waters and groundwater. The suitability of using chemical markers (i.e. fecal sterols, fluorescent whitening agents, pharmaceuticals and personal care products, and artificial sweeteners) and/or microbial markers (e.g. F+RNA coliphages, enteric viruses, and host-specific anaerobic bacterial 16S rDNA genetic markers) for tracking fecal pollution sources in receiving water bodies is discussed. In addition, this review also provides a comprehensive approach, which is based on the detection ratios (DR), detection frequencies (DF), and fate of potential microbial and chemical markers. DR and DF are considered as the key criteria for selecting appropriate markers for identifying and evaluating the impacts of fecal contamination in surface waters/groundwater.
Jin, P., Wang, X., Wang, X., Ngo, H.H. & Jin, X. 2015, 'A new step aeration approach towards the improvement of nitrogen removal in a full scale Carrousel oxidation ditch.', Bioresour Technol, vol. 198, pp. 23-30.
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Two aeration modes, step aeration and point aeration, were used in a full-scale Carrousel oxidation ditch with microporous aeration. The nitrogen removal performance and mechanism were analyzed. With the same total aeration input, both aeration modes demonstrated good nitrification outcomes with the average efficiency in removing NH4(+)-N of more than 98%. However, the average removal efficiencies for total nitrogen were 89.3% and 77.6% under step aeration and point aeration, respectively. The results indicated that an extended aerobic zone followed the aeration zones could affect the proportion of anoxic and oxic zones. The step aeration with larger anoxic zones indicated better TN removal efficiency. More importantly, step aeration provided the suitable environment for both nitrifiers and denitrifiers. The diversity and relative abundance of denitrifying bacteria under the step aeration (1.55%) was higher than that under the point aeration (1.12%), which resulted in an overall higher TN removal efficiency.
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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&copy; 2015 Elsevier B.V. All rights reserved. The effectiveness of a green bioflocculant (Gemfloc&reg;) on enhanced performance of a submerged membrane bioreactor (SMBR) was evaluated in terms of membrane fouling reduction and sludge characterization. Two MBRs were operated parallelly in this study, namely conventional MBR (CMBR) and MBR with Gemfloc&reg; addition (MBR-G). Results showed mitigated membrane fouling through Gemfloc&reg; addition in terms of cake layer formation and pore blocking. When compared to the CMBR, in spite of more extracellular polymeric substances (EPS) presented in activated sludge, the MBR-G demonstrated less soluble microbial products (SMP), larger sludge flocs, higher zeta potential and greater relative hydrophobicity of sludge flocs, which decreased cake layer resistance and pore blocking resistance. The reduced cake layer resistance in the MBR-G could be also ascribed to less growth of suspended biomass, lower sludge viscosity, as well as less EPS, SMP and biopolymer clusters in the cake layer. In addition, a modified resistance-in-series model was employed by considering SMP and mixed liquor suspended solids. The simulated results implied that the model could predict the influence of sludge characteristics on membrane fouling behavior of the SMBR.
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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&copy; The Royal Society of Chemistry. This study investigated the apparent zeta potential of fouled membranes for in-line coagulation membrane fouling monitoring in micro-polluted water treatment. Results show that the apparent zeta potentials are consistent with transmembrane pressures (TMPs) in both a direct filtration process and in-line coagulation ultrafiltration (C-UF). Furthermore, the curve between apparent zeta potential and filtration resistance of C-UF conformed to the form of the Michaelis-Menten equation. The changes of apparent zeta potential along with periodical backwashing were in accordance with the trend of TMP change. As a whole, apparent zeta potential could be a useful indicator for monitoring membrane fouling.
Thakur, I.S., Pandey, A. & Ngo, H.H. 2015, 'SPECIAL ISSUE ON "EMERGING TRENDS IN BIOTECHNOLOGY" Preface', INDIAN JOURNAL OF EXPERIMENTAL BIOLOGY, vol. 53, no. 6, pp. 315-315.
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.
Nguyen, D.D., Ngo, H. & Yoon, Y.S. 2014, 'A new hybrid treatment system of bioreactors and electrocoagulation for superior removal of organic and nutrient pollutants from municipal wastewater', Bioresource Technology, vol. 153, pp. 116-125.
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This paper evaluated a novel pilot scale hybrid treatment system which combines rotating hanging media bioreactor (RHMBR), submerged membrane bioreactor (SMBR) along with electrocoagulation (EC) as post treatment to treat organic and nutrient pollutants from municipal wastewater. The results indicated that the highest removal efficiency was achieved at the internal recycling ratio as 400% of the influent flow rate which produced a superior effluent quality with 0.26 mgBOD5 L-1, 11.46 mgCODCr L-1, 0.00 mgNH4-N L-1, and 3.81 mgT-N L-1, 0.03 mgT-P L-1. During 16 months of operation, NH4-N was completely eliminated and T-P removal efficiency was also up to 100%. It was found that increasing in internal recycling ratio could improve the nitrate and nitrogen removal efficiencies. Moreover, the TSS and coliform bacteria concentration after treatment was less than 5 mg L-1 and 30 PN mL-1, respectively, regardless of internal recycling ratios and its influent concentration.
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.
Tran, N.H., Nguyen, V., Urase, T. & Ngo, H. 2014, 'Role of nitrification in the biodegradation of selected artificial sweetening agents in biological wastewater treatment process', Bioresource Technology, vol. 161, pp. 40-46.
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The biodegradation of the six artificial sweetening agents including acesulfame (ACE), aspartame (ASP), cyclamate (CYC), neohesperidindihydrochalcone (NHDC), saccharin (SAC), and sucralose (SUC) by nitrifying activated sludge was first examined. Experimental results showed that ASP and NHDC were the most easily degradable compounds even in the control tests. CYC and SAC were efficiently biodegraded by the nitrifying activated sludge, whereas ACE and SUC were poorly removed. However, the biodegradation efficiencies of the ASs were increased with the increase in initial ammonium concentrations in the bioreactors. The association between nitrification and co-metabolic degradation was investigated and a linear relationship between nitrification rate and co-metabolic biodegradation rate was observed for the target artificial sweeteners (ASs). The contribution of heterotrophic microorganisms and autotrophic ammonia oxidizers in biodegradation of the ASs was elucidated, of which autotrophic ammonia oxidizers played an important role in the biodegradation of the ASs, particularly with regards to ACE and SUC.
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.
Kong, Q., Ngo, H., Shu, L., Fu, R., Jiang, C. & Miao, M. 2014, 'Enhancement of aerobic granulation by zero-valent iron in sequencing batch airlift reactor', Journal of Hazardous Materials, vol. 279, pp. 511-517.
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This study elucidates the enhancement of aerobic granulation by zero-valent iron (ZVI). A reactor aug-mented with ZVI had a start-up time of aerobic granulation (43 days) that was notably less than that fora reactor without augmentation (64 days). The former reactor also had better removal efficiencies forchemical oxygen demand and ammonium. Moreover, the mature granules augmented with ZVI had bet-ter physical characteristics and produced more extracellular polymeric substances (especially of protein).Three-dimensional-excitation emission matrix fluorescence showed that ZVI enhanced organic materialdiversity. Additionally, ZVI enhanced the diversity of the microbial community. Fe2+dissolution fromZVI helped reduce the start-up time of aerobic granulation and increased the extracellular polymericsubstance content. Conclusively, the use of ZVI effectively enhanced aerobic granulation.
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.
Nguyen, D.D., Ngo, H., Kim, S.D. & Yoon, Y.S. 2014, 'A specific pilot-scale membrane hybrid treatment system for municipal wastewater treatment', Bioresource Technology, vol. 169, pp. 52-61.
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A specifically designed pilot-scale hybrid wastewater treatment system integrating an innovative equalizing reactor (EQ), rotating hanging media bioreactor (RHMBR) and submerged flat sheet membrane bioreactor (SMBR) was evaluated for its effectiveness in practical, long-term, real-world applications. The pilot system was operated at a constant flux, but with different internal recycle flow rates (Q) over a long-term operating of 475 days. At 4Q internal recycle flow rate, BOD5, CODCr, NH4+-N, T-N, T-P and TSS was highly removed with efficiencies up to 99.88 &plusmn; 0.05%, 95.01 &plusmn; 1.62%, 100%, 90.42 &plusmn; 2.43%, 73.44 &plusmn; 6.03%, and 99.93 &plusmn; 0.28%, respectively. Furthermore, the effluent quality was also superior in terms of turbidity (<1 NTU), color (<15 TCU) and taste (inoffensive). The results indicated that with providing only chemically cleaned-in-place (CIP) during the entire period of operation, the membrane could continuously maintain a constant permeate flux of 22.77 &plusmn; 2.19 L/m2 h. In addition, the power consumption was also found to be reasonably low (0.921.62 kWh/m3).
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.
Nguyen, T.V., Loganathan, P., Vigneswaran, S., Krupanidhi, S., Pham, T.T.N. & Ngo, H.-.H. 2014, 'Arsenic waste from water treatment systems: characteristics, treatments and its disposal', Water Science and Technology-Water Supply, vol. 14, no. 6, pp. 939-950.
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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.
Liu, Q., Wang, X., Zhang, H., Shi, H., Hua, T. & Ngo, H. 2013, 'Characteristics of nitrogen transformation and microbial community in an aerobic composting reactor under two typical temperatures', Bioresource Technology, vol. 137, pp. 270-277.
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Batch experiments were conducted for feces composting using an aerobic composting reactor with sawdust as bulky matrix. In the 14-day composting processes at 35 &plusmn; 2 and 55 &plusmn; 2 C, compost samples were collected daily and chemical analyses and PCR-DGGE were carried out for investigating the influence of composting temperature on organic decomposition, nitrogen transformation, and microbial communities. At 55 &plusmn; 2 C, in addition to a slightly higher COD removal, nitrogen loss was greatly restrained. As organic nitrogen took about 85% of the total nitrogen originated from human feces, the suppression of ammonification process under thermophilic environment might be the main reason for less nitrogen loss at 55 &plusmn; 2 C. By PCR-DGGE analysis, the microbial community was found to undergo successions differently at 35 &plusmn; 2 and 55 &plusmn; 2 C. Certain sequences identified from the compost at 55 &plusmn; 2 C represented the microbial species which could perform nitrogen-fixation or sustain a lower pH in the compost so that gaseous ammonia emission was suppressed.
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.
Tran, N.H., Urase, T., Ngo, H., Hu, J. & Ong, S.L. 2013, 'Insight into metabolic and cometabolic activities of autotrophic and heterotrophic microorganisms in the biodegradation of emerging trace organic contaminants', Bioresource Technology, vol. 146, no. 1, pp. 721-731.
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Many efforts have been made to understand the biodegradation of emerging trace organic contaminants (EOCs) in the natural and engineered systems. This review summarizes the current knowledge on the biodegradation of EOCs while having in-depth discussion on metabolism and cometabolism of EOCs. Biodegradation of EOCs is mainly attributed to cometabolic activities of both heterotrophic and autotrophic microorganisms. Metabolism of EOCs can only be observed by heterotrophic microbes. Autotrophic ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaeal (AOA) cometabolize a variety of EOCs via the non-specific enzymes, such as ammonia monooxygenase (AMO). Higher biodegradation of EOCs is often noted under nitrification at high ammonia loading rate. The presence of a growth substrate promotes cometabolic biodegradation of EOCs. Potential strategies for enhancing the biodegradation of EOCs were also proposed in this review.
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.
Shim, W.G., Mohammed Abdul, J., Mohammed, T.M., Vigneswaran, S., Ngo, H. & Kandasamy, J.K. 2012, 'Biofilter In Leachate Treatment Processes', Desalination and Water Treatment, vol. 41, no. 1-3, pp. 249-257.
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Landfill leachate is produced when rainwater infiltrates into the landfill and permeates through the decomposing waste within the landfill leaching out with it contaminants and pollutants. Untreated leachates can permeate ground water or mix with surface
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.
Chiemchaisri, W., Chiemchaisri, C., Dumrongsukit, C., Threedeach, S., Ngo, H. & Vigneswaran, S. 2011, 'Removal Of Water-Borne Microorganisms In Floating Media Filter-Microfiltration System For Water Treatment', Bioresource Technology, vol. 102, no. 9, pp. 5438-5443.
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Floating plastic media pre-filter (PP) in combination with microfiltration membrane (MF) was applied to the removal of water-borne microorganism from surface water. The system was operated with and with-out coagulant addition. Jar-test results suggested
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
Nguyen, V., Zhang, R., Vigneswaran, S., Ngo, H., Kandasamy, J.K. & Mathes, P. 2011, 'Removal of organic matter from effluents by Magnetic Ion Exchange (MIEX)', Desalination, vol. 276, no. 1-3, pp. 96-102.
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Magnetic Ion Exchange Resin (MIEX&Acirc;&reg;) is effective in removing the majority of organic carbon from biologically treated wastewater. It removed 77% of dissolved organic carbon (DOC) from synthetic wastewater when operated in batch mode using a MIEX&Acirc;&reg; concentration of 10 mL/L. A pseudo secondorder reaction rate model namely the Ho model was used for the kinetic study and it was found that it provided a realistic description of the adsorption kinetics of DOC. A fluidised bed MIEX&Acirc;&reg; contactor effectively removed organic matter from synthetic biologically treated sewage effluent with more than 60% DOC removal even after 172 bed volumes. The regenerated MIEX&Acirc;&reg; resin did not display any significant reduction in its ability to remove organic matter.
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.
Wang, X.C., Luo, L., Chen, R. & Ngo, H. 2011, 'Thermodynamic analysis of an urban water system with reclaimed water as supplemental water resource', Desalination and Water Treatment, vol. 32, pp. 307-315.
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The natural water system maintains its dynamic equilibrium through a hydrological cycle that involves a series of natural processes. Such a natural water cycle has been much disturbed by human activities in the process of water use. An urban water system was thus modeled in this paper as a series of artificial water cycles overlaid upon the natural water cycle. The system was thermodynamically analyzed by calculating the entropy budget as &Icirc;S = &Icirc;iS + &Icirc;eS where &Icirc;iS and &Icirc;eS are the entropy increases due to natural and artificial contributions, respectively. The natural water cycle free from human disturbance should possess the nature of self maintenance of water and materials balance and could be assumed as a pseudo-reversible process with &Icirc;iS 0. &Icirc;eS was then supposed as to be contributed by artificial disturbances on water quantity such as by water withdrawal, and on water quality such as by pollutant discharge. A series of models were developed for calculating &Icirc;eS. As a result of scenario analysis of urban water system in Xi'an, a metropolitan in northwestern China, using these models, it was indicated that under the current condition of water supply and wastewater treatment, if 20% of the treated wastewater could be reused, &Icirc;eS would be decreased by 15.22% from the current level, while if the percent of treated wastewater reuse could be increased to 40%, &Icirc;eS would be decreased by 29.93%. Thermodynamic analysis thus provided a tool for quantitative evaluation of the effect of urban wastewater reclamation and reuse.
Mullai, P., Arulselvi, S., Ngo, H. & Sabarathinam, P. 2011, 'Experiments And Anfis Modelling For The Biodegradation Of Penicillin-G Wastewater Using Anaerobic Hybrid Reactor', Bioresource Technology, vol. 102, no. 9, pp. 5492-5497.
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The performance of an anaerobic hybrid reactor (AHR) for treating penicillin-G wastewater was investigated at the ambient temperatures of 30-35 degrees C for 245 days in three phases. The experimental data were analysed by adopting an adaptive network-ba
Yang, Y.L., Li, J., Wang, H., Song, X., Wang, T., He, B., Liang, X. & Ngo, H. 2011, 'An Electrocatalytic Membrane Reactor With Self-Cleaning Function For Industrial Wastewater Treatment', Angewandte Chemie-International Edition, vol. 50, no. 9, pp. 2148-2150.
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Industrial wastewater has become a global issue due to its high concentration of pollutants, especially refractory organic compounds.[1] Membrane technology has attracted considerable attention in industrial wastewater purification over the past decades owing to its high flexibility regarding water quality and low investment costs. However, inherent membrane fouling caused by concentration polarization and pore blocking leads to low plant reliability and limits wide industrial application in wastewater treatment.[2] Controlling and mitigating membrane fouling has become the most critical problem in the field of membrane technology for water and wastewater treatment.
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.
Ho, D., Vigneswaran, S., Ngo, H., Shon, H., Kandasamy, J.K., Chang, Y. & Chang, J. 2011, 'Photocatalysis of Trimethoprim (TRI) in Water', Sustainable Environment Research (SER), vol. 21, no. 3, pp. 149-154.
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The advantage of the use of photocatalysts to treat persistent organic pollutants (POP) was demonstrated with the decomposition of trimethoprim (TRI), an antibiotic most frequently detected in municipal wastewaters and surface waters. In this study, the oxidation process by UV/TiO2 was employed as an alternative to advanced oxidation process (AOP) to remove residual antibiotics from water. High concentrations of TRI were used to study the efficiency of photocatalysis. Both batch and continuous photoreactors were used. The decomposition of TRI by TiO2/UV photooxidation occurred gradually over time. On the other hand, with UV irradiation alone, the reduction of TRI mineralization was relatively small. The effect of light intensity showed there was no significant impact of UV light intensity on the degradation of TRI in the range of increasing intensities studied. The simulation using first-order kinetics provided a good fit with the experimental data. In the continuous system, the feed flow rate was adjusted to maximize the percentage of mineralization of targeted compounds inside the photoreactor. A lower flow rate, i.e., higher detention time, achieved higher percentage of TRI mineralization. The results indicated that TiO2/UV irradiation was effective in removing TRI.
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.
Yang, Y., Li, J., Wang, H., Song, X., Wang, T., He, B., Liang, X. & Ngo, H.H. 2011, 'An electrocatalytic membrane reactor with self-cleaning function for industrial wastewater treatment.', Angew Chem Int Ed Engl, vol. 50, no. 9, pp. 2148-2150.
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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.
Park, K.H., Shim, W.G., Shon, H., Lee, S.G., Ngo, H., Vigneswaran, S. & Moon, H. 2010, 'Adsorption Characteristics of Acetaldehyde on Activated Carbons Prepared from Corn-Based Biomass Precursor', Separation Science and Technology, vol. 45, no. 8, pp. 1084-1091.
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The ACs (R-1/2 and R-1/4) having two different textual and chemical properties are prepared from corn-based biomass precursor and evaluated together with a wood-based activated carbon (WAC) at room temperature using a gas chromatograph. The results obtained from the correlation studies indicate that the pore size distribution (below 8A &Euml; ) and the relatively lower energetic heterogeneity of ACs on acetaldehyde adsorption are considerable factors rather than that of a specific surface area and surface chemistry. The adsorption equilibrium of ACs is well correlated with the Sips equation. The pseudo second-order equation was better in describing the ACs&acirc; adsorption kinetic of acetaldehyde.
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
Ren, X., Shon, H., Jang, N., Lee, Y.G., Bae, M., lee, J., Cho, K. & Kim, I.S. 2010, 'Novel membrane bioreactor (MBR) coupled with a nonwoven fabric filter for household wastewater treatment', Water Research, vol. 44, no. 3, pp. 751-760.
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Conventional and modified membrane bioreactors (MBRs) are increasingly used in small-scale wastewater treatment. However, their widespread applications are hindered by their relatively high cost and operational complexity. In this study, we investigate a new concept of wastewater treatment using a nonwoven fabric filter bag (NFFB) as the membrane bioreactor. Activated sludge is charged in the nonwoven fabric filter bag and membrane filtration via the fabric is achieved under gravity flow without a suction pump. This study found that the biofilm layer formed inside the NFFB achieved 10 mg/L of suspended solids in the permeate within 20 min of initial operation. The dynamic biofilter layer showed good filterability and the specific membrane resistance consisted of 0.3&acirc;1.9 &Atilde; 1012 m/kg. Due to the low F/M ratio (0.04&acirc;0.10 kg BOD5/m3/d) and the resultant low sludge yield, the reactor was operated without forming excess sludge. Although the reactor provided aerobic conditions, denitrification occurred in the biofilm layer to recover the alkalinity, thereby eliminating the need to supplement the alkalinity. This study indicates that the NFFB system provides a high potential of effective wastewater treatment with simple operation at reduced cost, and hence offer an attractive solution for widespread use in rural and sparsely populated areas.
Ho, D., Vigneswaran, S. & Ngo, H. 2010, 'Integration of Photocatalysis and Microfiltration in Removing Effluent Organic Matter from Treated Sewage Effluent', Separation Science and Technology, vol. 45, no. 2, pp. 155-162.
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An integration of photocatalysis with low-pressure submerged membrane has attracted growing interest for its synergic advantages in water and wastewater treatment. In this study, the adsorption and photocatalytic oxidation of organic compounds by UV light responsive titanium dioxide (TiO2) were investigated. First, the adsorption behavior of the TiO2 was examined by the adsorption isotherm and kinetics experiments. The photocatalytic reactivity of the catalysts was then compared at different operating conditions. The results indicate that the Freundlich model described well the adsorption capacity of both materials. The photocatalytic kinetics showed that the highest removal of effluent organic matter (EfOM) was achieved at an optimum concentration of 1.0 g/L of TiO2. In addition, it was found that the pre-photosensitization with titanium dioxide/ultra-voilet radiation (TiO2/UV) could effectively reduce membrane fouling and enhance the permeate flux of the submerged membrane reactor when it was used as a post-treatment. An increase of 10% in organic removal efficiency was achieved by the posttreatment of membrane filtration. The sustainable flux of the membrane reactor increased from 25 up to 40 L/m2.h when the pretreatment of photocatalysis was used.
Chinu, K.J., Vigneswaran, S., Erdei, L., Shon, H., Kandasamy, J.K. & Ngo, H. 2010, 'Comparison of fouling indices in assessing pre-treatment for seawater reverse osmosis', Desalination and Water Treatment, vol. 18, no. 1-5, pp. 187-191.
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In this study, different processes such as flocculation with ferric chloride (FeCl3) and deep bed filtration (sand filtration and dual media filtration) as a pre-treatment were used for seawater desalination. The performance of these pre-treatments was determined in terms of silt density index (SDI) and modified fouling index by using microfilter (MF-MFI), ultrafilter (UF-MFI), and nanofilter (NF-MFI) membrane. MFI and SDI indicated that deep bed filtration with in-line flocculation was better pre-treatment than flocculation alone as colloidal particles are removed after this pretreatment. UF-MFI and NF-MFI indicated that these pretreatment cannot remove dissolved organic matter as the fouling reduction was smaller. Detailed molecular weight distribution (MWD) of seawater organic matter was examined after different pretreatments. MWD of the initial seawater mainly ranged from 1510 Da to 130 Da. Deep bed filtration with in-line flocculation removed relatively large molecular weight of organic matter (1510&acirc;1180 Da), while the small molecular weights (less than 530 Da) were not removed.
Nguyen, V., Vigneswaran, S., Ngo, H. & Kandasamy, J.K. 2010, 'Arsenic removal by iron oxide coated sponge: Experimental performance and mathematical models', Journal of Hazardous Materials, vol. 182, no. 1-3, pp. 723-729.
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Millions of people worldwide are at risk from the presence of arsenic in groundwater. In this study, adsorption equilibrium and long term experiments were carried out to evaluate the performance of iron oxide coated sponge (IOCSp) in arsenic removal. It was found that maximum adsorption capacity of IOCSp for As(III) and As(V) calculated by Sips isotherm was 4.2 and 4.6 mg/g of IOCSp, respectively. A filter packed with small amount of 25 g IOCSp maintained a consistent arsenic removal efficiency of 95% from synthetic solution containing arsenic concentration of as high as 1000g/L. This produced a throughput volume of 153 and 178 L of water containing As III) and As(V), respectively before any need for regeneration or disposal of IOCSp. IOCSp could be regenerated by washing it with NaOH solution. The dynamic (column) adsorption kinetics were successfully predicted by the Thomas and Nikolaidis modified models.
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.
Kim, S.H., Shon, H. & Ngo, H. 2010, 'Adsorption Characteristics Of Antibiotics Trimethoprim On Powdered And Granular Activated Carbon', Journal of Industrial and Engineering Chemistry, vol. 16, no. 3, pp. 344-349.
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The adsorption characteristics of trimethoprim (TMP) onto powdered activated carbon (PAC) and granular activated carbon (GAC) were studied. The adsorption isotherms could be plotted using the Langmuir, Freundlich and Toth models with a reasonable degree
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
Ho, D., Senthilnanthan, M., Mohammad, J., Vigneswaran, S., Ngo, H., Mahinthakumar, G. & Kandasamy, J.K. 2010, 'The Application Of Photocatalytic Oxidation In Removing Pentachlorophenol From Contaminated Water', Journal of Advanced Oxidation Technologies, vol. 13, no. 1, pp. 21-26.
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The degradation of sodium salt of pentachlorophenol (PCPS) by photocatalysis with titanium dioxide (TiO2) as the catalyst was investigated. The residual PCPS after photo-degradation was analyzed by high performance liquid chromatograph (HPLC) while the c
Senthilnanthan, M., Ho, D., Vigneswaran, S., Ngo, H. & Shon, H. 2010, 'Visible light responsive ruthenium-doped titanium dioxide for the removal of metsulfuron-methyl herbcide in aqueous phase', Separation and Purification Technology, vol. 75, no. 3, pp. 415-419.
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Titanium dioxide (TiO2) under UV light irradiation is one of the effective treatment methods to reduce the concentration of synthetic organic compounds in water. Nevertheless, only a small amount of UV light is absorbed in the solar light. This makes the less use of TiO2 for environmental applications. In this study, we prepared Ru-doped visible light responsive (VLR) TiO2 to improve visible light absorption and characterized it in terms of physical and chemical properties. The photocatalytic activity of VLR Rudoped TiO2 was investigated to remove metsulfuron-methyl (MSM) in aqueous phase. The Ru-doped TiO2 at different Ru concentrations was found to have the anatase phase. The undoped and Ru-doped TiO2 consisted of regular round shape. The photocatalytic activity of VLR photocatalyst was significantly improved on the addition of Ru from 40% for undoped TiO2 to 80% for Ru-doped TiO2. The removal efficiency of MSM was proportional to the increasing Ru-doped TiO2 under visible light. As the calcined temperature increased from 300 to 900 &acirc;&brvbar;C, the degradation efficiencies moderately changed from 65 to 90%. However, the effect of calcination duration was marginal on the photodegradation of MSM.
Ngo, H. 2010, 'Visible light responsive ruthenium-doped titanium dioxide for the removal of metsulfuron-methyl herbcide in aqueous phase', Separation and Purification Technology, vol. 75, pp. 415-419.
Jegatheesan, V., Shu, L. & Ngo, H.H. 2010, 'Special issue on the Challenges in Environmental Science and Engineering, CESE-2009 14-17 July, 2009--Jupiters Hotel, Townsville, Queensland, Australia.', Bioresource technology, vol. 101, no. 5, p. 1415.
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Ho, D., Vigneswaran, S. & Ngo, H. 2009, 'Photocatalysis - membrane hybrid system for organic removal from biological treated sewage effluent', Separation and Purification Technology, vol. 68, no. 2, pp. 145-152.
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The application of semiconductor photocatalysis in treating wastewater has attracted growing interest due to its complete mineralisation of organic matter. Furthermore, coupling of photocatalytic process with microfiltration provided considerable advantages over the conventional methods. In this study, the photocatalytic reactivity of the catalysts was assessed at different operating conditions. The results show that the dissolved organic carbon (DOC) content was halved at a concentration of 1.0 g/L of TiO2. With the addition of flocculant FeCl3, the oxidation process was significantly improved further by another 30%. The recovery of TiO2 upon photooxidation process was achieved by coupling the photocatalysis reactor with a low energy submerged membrane reactor. The results show superior DOC degradation of more than 80% by this hybrid system. Moreover, it was demonstrated that photosensitization with TiO2/UV could effectively reduce membrane fouling and enhance the permeate flux of the submerged membrane reactor.
Nguyen, V., Vigneswaran, S., Ngo, H., Shon, H. & Kandasamy, J.K. 2009, 'Arsenic removal by a membrane hybrid filtration system', Desalination, vol. 236, no. 1-3, pp. 363-369.
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Arsenic is a toxic semi-metallic element that can be fatal to human health. Membrane filtration can remove a number of contaminants from water, including arsenic. Removal of arsenic by membrane filtration is highly dependent on the species of arsenic and the properties of the membrane. The performance of the nanofilter is better for removing As(V) than As(III). About 57% of As(III) and 81% of As(V) was removed from 500 mg/L arsenic solutions by nanofiltration (NTR729HF, Nitto Denko Corp., Japan) of 700 molecular weight (MW) cutoff. The removal efficiency of microfiltration (MF) was much lower than that of nanofiltration (NF) due to its larger pore size. By comparison only 37% of As(III) and 40% of As(V) were removed by microfiltration (PVA membrane, Pure-Envitech, Korea). However, the removal efficiency of microfiltration was increased dramatically when a small amount of nanoscale zero valent iron (nZVI) was added. The removal efficiency by MF increased up to 90% with As(V) and 84% with As(III) when an amount of 0.1 g/L of nZVI was added into the arsenic solution.
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.
Chiemchaisri, C., Passananon, S., Ngo, H. & Vigneswaran, S. 2009, 'Simultaneous removal of particles and dissolved organic matter in floating media filter for surface water treatment', Desalination and Water Treatment, vol. 11, no. 1-3, pp. 109-114.
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This research investigated the performance of fl oating media fi lter in removing particles and dissolved organic matter from surface water. Pilot-scale study consists of fl oating plastic media pre-fi lter connected with either granular activated carbon (GAC) or sponge biological fi lter (BF) bed. In the fl oating plastic media fi lter, coagulation and fl occulation processes using poly-aluminum chloride (PACl) as coagulant at an optimum dose of 8 mg/L helped removing particles from raw water. The fl oating media fi lter was operated a fi ltration rate of 11 m3/m2.h whereas those in GAC and BF units were maintained at 2 m3/m2.h. Continuous operation for over 120 days gave 98% and 99% average removal effi ciencies of turbidity and UV254 in fl oating media fi lter in combination with GAC unit whereas and 78% and 52% removal effi ciencies of turbidity and UV254 removal were obtained in fl oating media fi lter in combination with BF. The removal of dissolved organic carbon in GAC and BF units reduced chlorine demand for disinfection by 29% and 14%. It could also reduce the sum of trihalomethane (THMs) ratio from 1.1 to 0.1 and 0.5 respectively.
Nguyen, V., Nguyen, T., Pham, T.L., Vigneswaran, S., Ngo, H., Kandasamy, J.K., Nguyen, H. & Nguyen, T.D. 2009, 'Adsorption and removal of arsenic from water by iron ore mining waste', Water Science and Technology, vol. 60, no. 9, pp. 2301-2308.
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There is a global need to develop low-cost technologies to remove arsenic from water for individual household water supply. In this study, a purified and enriched waste material (treated magnetite waste, TMW) from the Trai Cau's iron ore mine in the Thai Nguyen Province in Vietnam was examined for its capacity to remove arsenic. The treatment system was packed with TMW that consisted of 75% of ferrous-ferric oxide (Fe3O4) and had a large surface area of 89.7 m2/g. The experiments were conducted at a filtration rate of 0.05 m/h to treat groundwater with an arsenic concentration of 380 mg/L and iron, manganese and phosphate concentrations of 2.07 mg/L, 0.093 mg/L and 1.6 mg/L respectively. The batch experimental results show that this new material was able to absorb up to 0.74 mg arsenic/g. The results also indicated that the treatment system removed more than 90% arsenic giving an effluent with an arsenic concentration of less than 30 mg/L while achieving a removal efficiency of about 80% for Mn2 + and PO43-. This could be a promising and cost-effective new material for capturing arsenic as well as other metals from groundwater
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).
Nguyen, V., Rahman, A., Vigneswaran, S., Ngo, H., Kandasamy, J.K., Nguyen, T.D., Do, A.T. & Nguyen, K.T. 2009, 'Arsenic removal by iron oxide coated sponge: treatment and waste management', Water Science and Technology, vol. 60, no. 6, pp. 1489-1495.
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One of the problems in drinking water that raises concern over the world is that millions of people still have to use arsenic-contaminated water. There is a worldwide need to develop appropriate technologies to remove arsenic from water for household and community water supply systems. In this study, a new material namely iron oxide coated sponge (IOCSp) was developed and used to remove arsenic (As) from contaminated groundwater in Vietnam. The results indicated that IOCSp has a high capacity in removing both As (V) and As (III). The adsorption capacity of IOCSp was up to 4.6mg As/g IOCSp, showing better than many other materials. It was observed from a pilot study that a small quantity of IOCSp (180 g) could reduce As concentration of 480mg/L in 1.5m3 of contaminated natural water to below 40 mg/L. In addition, an exhausted IOCSp, containing a large amount of arsenic (up to 0.42 wt %) could safely be disposed through the solidification/stabilization with cement. Addition of fly ash also reduced the amount of arsenic in the leachate.
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.
Hoang, T., Vigneswaran, S., Ngo, H., Kandasamy, J.K., Shim, W.G., Chaudhary, D.S., Gotety, B.P. & Peiris, P. 2008, 'Performance evaluation and mathematical modelling of granular activated carbon biofiltration in wastewater treatment', Korean Journal of Chemical Engineering, vol. 25, no. 2, pp. 259-267.
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Biological filtration is an effective technique for removing organic matter from wastewater. The performance of a biofilter can be influenced by a range of operational conditions. In this study the performance of biofilters was investigated for the influence of filter media depth, influent concentrations, filtrations rates and backwashing. The results show that performance of GAC filters decreased with shallower filter bed depths. In addition, the GAC performed better at lower influent concentration and lower filtration rates. The daily backwash adopted to avoid the physical clogging of the biofilter did not have any significant effect on the organic removal efficiency of the filter. The concentration, activity and characteristics of the biomass are quantified and described. A mathematical model was developed to simulate the organic removal of the GAC biofiltration system. The performance of the GAC filter under different influent organic concentration levels, filtration rates and filter bed depths was adequately simulated by the mathematical model developed for this study.
Areerachakul, N., Vigneswaran, S., Ngo, H. & Kandasamy, J.K. 2008, 'A continuous photocatalysis system in the degradation of herbicide', Korean Journal of Chemical Engineering, vol. 25, no. 4, pp. 663-669.
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The performance of both batch and continuous photo-catalytic reactors was studied to evaluate their capabilities in removing the sulfonyl urea herbicide of metsulfuron methyl (MM). It was found in a batch reactor that the addition of a small amount of powder activated carbon (PAC) significantly increased the rate of degradation of MM. The continuous photo-catalytic system resulted in 57% of MM removal. When a small dose of activated carbon was added in the photo-catalytic system, MM removal increased to 7886% MM removal for retention times between of 5.2521 min (corresponding to withdrawal rates of 1040 mLmin-1). In this study, the pseudo first order rate constants of a continuous photo-catalytic system revealed that shorter retention times were associated with lower rate constants. Solid phase micro extraction/gas chromatography (SPME/GC) results showed that high concentrations of MM were broken down to small volatile organic compounds (VOCs) by photo-catalytic oxidation. PAC adsorbed the photo-products and increased the degradation of MM.
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.
Chiemchaisri, C., Passananon, S., Ngo, H. & Vigneswaran, S. 2008, 'Enhanced natural organic matter removal in floating media filter coupled with microfiltration membrane for river water treatment', Desalination, vol. 234, no. 1-3, pp. 335-343.
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This research work was carried out to determine natural organic matter (NOM) removal in floating media filter coupled with microfiltration membrane applied to the treatment of river water in Bangkok, Thailand. Polyaluminum chloride was found to be the most effective coagulant providing enhanced coagulation effect for NOM removal. Optimum filtration rate of floating media filter was 11 m3/m2 h at which highest NOM removal efficiencies of 82.2% was achieved. Subsequent treatment in microfiltration membrane unit operated at a filtration rate of 0.45 m3/m2 d provided total NOM removal of 85.786.6%. Periodical cleanings of floating media filter and microfiltration membrane were accomplished by using air scouring coupled with water flushing at every 8 and 24 h interval. As a result of NOM removal, the sum of trihalomethane (THM) ratio was reduced from 0.51.1 in raw water to 0.20.6 in treated water. Membrane fouling study revealed that both turbidity and NOM affected transmembrane pressure (TMP) built up but particulate fouling provided greater impact on TMP as compared to organic adsorption on the membrane surface.
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.
Nguyen, V., Vigneswaran, S., Ngo, H., Kandasamy, J.K. & Choi, H. 2008, 'Arsenic removal by photo-catalysis hybrid system', Separation and Purification Technology, vol. 61, no. 1, pp. 44-50.
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Arsenic is a toxic semi-metallic element that can be fatal to human health. Arsenic pollution in water is found in many parts of the world, especially in developing countries such as Bangladesh, India, Nepal, and Vietnam. Photo-oxidation experiments with titanium dioxide (TiO2) as photo-catalyst showed that photo-oxidation of As(III) to As(V) is possible within minutes. Further, TiO2 can also adsorb both As(III) and As(V) on its surface. Photo-catalysis reaction with TiO2 reduced about 98% of arsenite from water containing 500 ?g/L of arsenite. By adding nano-scale zero valent iron (nZVI) of 0.05 g/L in the photo-reactor, arsenic removal can be significantly enhanced. Further the TiO2 requirement is five times less in this photo-catalysis nZVI hybrid system. The photo-catalytic degradation processes was modeled using the first-order, second-order and LangmuirHinshelwood kinetics equations and removal rates were simulated.
Zhang, R., Vigneswaran, S., Ngo, H. & Nguyen, H.V. 2008, 'Fluidized bed magnetic ion exchange (MIEX) as pre-treatment process for a submerged membrane reactor in wastewater treatment and reuse', Desalination, vol. 227, no. 1-3, pp. 85-93.
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Magnetic ion exchange (MIEX) resin can effectively remove significant amounts of organic matter from biologically treated sewage effluent. The MIEX process has mainly been used as a batch process, which requires a large area for accommodating both contact tank and settling tank in the treatment process. In this study, a fluidized bed MIEX reactor (a semi-continuous process) was used as a pre-treatment for a submerged membrane. When used as a pre-treatment for a submerged membrane, the fluidized bed MIEX contactor could remove a significant amount of organic matter in the wastewater (80% removal). This pre-treatment helped to reduce membrane fouling and keep transmembrane pressure low during the membrane operation of 8 h (less than 19 kPa). The regeneration of MIEX resin (number of regeneration, regeneration time, etc.) did not have any adverse effect on the organic removal by MIEX
Kim, S., Ngo, H., Shon, H. & Vigneswaran, S. 2008, 'Adsorption and Photocatalysis Kinetics of Herbicide onto Titanium Oxide and Powdered Activated Carbon', Separation and Purification Technology, vol. 58, no. 3, pp. 335-342.
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The adsorption and photocatalysis kinetics of metsulfuron-methyl (MM) onto titanium oxide (TiO2) and powdered activated carbon (PAC) were studied at varying adsorbent amount and MM concentration. The overall mass transfer in adsorption was estimated from concentration decay curves obtained in the batch adsorber. The maximum adsorption capacity decreased with increasing adsorbent amount in TiO2 adsorption. The adsorption isotherms of MM could be plotted using the Langmuir isotherm model with a reasonable degree of accuracy having higher r2 values rather than Freundlich isotherm model. Linear driving force approximation (LDFA) kinetic equation with Langmuir adsorption isotherm model was successfully applied to predict the adsorption kinetics data in various concentrations of MM in photobatch reactor. The estimated mass transfer coefficient was used to be 3.0 10-5, 5.5 10-5, 9.1 10-5 m/s in PAC adsorption and 2.0 10-5, 1.1 10-5, 9.0 10-6 m/s in TiO2 adsorption for a different MM concentration of 20, 50 and 70 mg/L, respectively. Photocatalysis kinetics was same with TiO2 of 0.2 g/L regardless of TiO2 amounts and the MM degradation kinetics was enhanced by TiO2 catalysis rather than only UV light degradation. Among the photocatalysis kinetics model with first-order, second-order and LangmuirHinshelwood (LH) model, a second-order kinetic model was found to well present the experimental data of MM by TiO2 catalyst for the range of various TiO2 amounts and MM concentration studied.
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
Zhang, R., Vigneswaran, S., Ngo, H. & Nguyen, H.V. 2007, 'A Submerged Membrane Hybrid System Coupled With Magnetic Ion Exchange (miex (r)) And Flocculation In Wastewater Treatment', Desalination, vol. 216, no. 1-3, pp. 325-333.
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Wastewater treated by conventional secondary and tertiary processes cannot be reused directly without further treatment. The membrane process can achieve a high quality effluent, but membrane fouling caused by organic matter affects membrane performance
Shon, H., Vigneswaran, S., Kim, J.K. & Ngo, H. 2007, 'Application Of Hybrid Photocatalysis Systems Coupled With Flocculation And Adsorption To Biologically Treated Sewage Effluent For Organic Removal', Korean Journal Of Chemical Engineering, vol. 24, no. 4, pp. 618-623.
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The application of a photocatalysis hybrid system coupled with flocculation and adsorption in treating biologically treated sewage effluent (BTSE) was investigated. The removal of organic matter was studied in terms of dissolved organic matter (DOC), rem
Shon, H., Vigneswaran, S., Ngo, H., Kim, J.K. & Kandasamy, J.K. 2007, 'Effect Of Flocculation As A Pretreatment To Photocatalysis In The Removal Of Organic Matter From Wastewater', Separation And Purification Technology, vol. 56, no. 3, pp. 388-391.
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Effects of different flocculants (chloride-based salts and ferric and ferrous salts) and initial organic concentration of wastewater on flocculation-photocatalysis hybrid process were investigated. Titanium dioxide (TiO2) adsorption alone, flocculation a
Dunphy, A.J., Beecham, S.C., Vigneswaran, S., Ngo, H., McLaughlan, R.G. & Collins, A.P. 2007, 'Development of a Confined Water Sensitive Urban Design (WSUD) System Using Engineered Soils', Water Science and Technology, vol. 55, no. 4, pp. 211-214.
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Innovative Water Sensitive Urban Design (WSUD) systems are being investigated at three locations to the north and south of Sydney, Australia. These systems contain porous concrete pipes that are designed so that stormwater exfiltrates through the permeable walls of the pipes into the surrounding substrate media material. The porous pipes and media material treat the passing stormwater. The primary aim of the overall project is to develop a model to describe the treatment effectiveness of confined WSUD systems. This paper focuses on the system located at the Weathertex Industrial Site, Heatherbrae. Due to wood processing operations that occur at this site, it is recognised that the surface runoff will carry a heavy organics loading. Granulated Activated Carbon (GAC) is recognised for its ability to reduce the concentration of dissolved organics present in both wastewater and stormwater. GAC was therefore chosen as a filtration medium to be investigated at this site. To maximise the effectiveness of the GAC, extensive laboratory batch studies were undertaken prior to the field system being constructed to determine the optimum GAC/sand ratio. The purpose of the experimental work was to assess the dissolved organic removal potential through sorption of various concentrations of GAC. The aim of this paper is to describe these laboratory experiments and discuss how they related to the field system. Through these experiments it was determined that a sand/GAC ratio of 25:1 was ideal for the media material at the Heatherbrae site.
Kim, S. & Ngo, H. 2007, 'Adsorption Characteristics and pH-dependence of Metsulfuron-Methyl onto Activated Carbons', Separation Science and Technology, vol. 42, no. 8, pp. 1731-1745.
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The adsorption characteristics of metsulfuron-methyl (MM) onto powdered activated carbon (PAC) and granular activated carbon (GAC) were studied at varying solution pHs (49) and temperatures (20408C). The dependence of pH was observed in aqueous solution with MM. The film mass transfer and intraparticle diffusion coefficients were estimated from concentration decay curves obtained in the batch adsorber. The maximum adsorption capacity decreased with increasing pH and temperature. Among the PAC used, the coconut based PAC had the best adsorption capacity. The adsorption isotherms could be plotted using the Freundlich and Toth models with a reasonable degree of accuracy. The overall adsorption isotherm such as the modified-Toth model should be applied. The performances of the fixed-bed GAC system was also simulated by a model developed. The objective of the present study was to investigate the adsorption and pH dependence behavior of MM onto PAC and GAC in order to diminish the environmental risk of MM pollution.
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
Shon, H., Smith, P.J., Vigneswaran, S. & Ngo, H. 2007, 'Effect Of A Hydrodynamic Cleaning Of A Cross-flow Membrane System With A Novel Automated Approach', Desalination, vol. 202, no. 1-3, pp. 351-360.
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The effect of different hydraulic cleaning methods was investigated in terms of flux decline and resistance using the cross-flow UF unit. The use of varied production intervals, varied ratios of periodic relaxation and the use of a periodic high-rate cro
Areerachakul, N., Vigneswaran, S., Ngo, H. & Kandasamy, J.K. 2007, 'Granular activated carbon (GAC) adsorption-photocatalysis hybrid system in the removal of herbicide from water', Separation And Purification Technology, vol. 55, no. 2, pp. 206-211.
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The performance of the granular activated carbon (GAC) fixed bed adsorption, the continuous photocatalysis systems and a combination of the two were studied to evaluate their capabilities in removing the herbicide of metsulfuron-methyl (MM) from waste wa
Shon, H., Vigneswaran, S., Kim, J.H. & Ngo, H. 2007, 'Application of a Photocatalysis System to Wastewater: A Detailed Organic Removal of different fractions', Studies in Surface Science and Catalysis, vol. 172, pp. 559-560.
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A removal of detailed organic matter by photocatalysis was investigated in terms of molecular weight (MW) distribution and fraction (hydrophobic (HP), transphilic (TP) and hydrophilic (HL)). The photooxidation with TiO, removed the majority of MW (263 daltons, 580, 865, and 43109). Effluent organic matter (EfOM) removal in wastewater was high (80%) for HP and TP components. EfOM removal from the HL fraction was however minimum, suggesting that the HL fraction may be the fraction of low activity in photocatalytic degradation. Thus, the HL fraction has to be removed from BTSE in the application of photocatalysis for the purpose of wastewater reuse
Shon, H., Vigneswaran, S. & Ngo, H. 2006, 'Effect of partial flocculation and adsorption as pretreatment to ultrafiltration', Aiche Journal, vol. 52, no. 1, pp. 207-216.
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In this study, the sufficiency of flocculation and adsorption with reduced doses of ferric chloride and powdered activated carbon (PAC) as pretreatment to ultrafiltration. (UF) was investigated. A 50 mg/L dose of FeCl3 and 0.5 g/L of PAC removed a majori
Nguyen, V., Vigneswaran, S., Ngo, H., Pokhrel, D. & Viraraghavan, T. 2006, 'Specific treatment technologies for removing arsenic from water', Engineering In Life Sciences, vol. 6, no. 1, pp. 86-90.
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Arsenic (As) is a highly toxic metalloid found in ground and surface water. Arsenic contamination in drinking water leads to harmful effects on human health. To eliminate arsenic from drinking water, several technologies such as coagulation, adsorption,
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
Zhang, R., Vigneswaran, S., Ngo, H. & Nguyen, H.V. 2006, 'Magnetic ion exchange (MIEX (R)) resin as a pre-treatment to a submerged membrane system in the treatment of biologically treated wastewater', Desalination, vol. 192, no. 1-3, pp. 296-302.
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Magnetic ion exchange (MIEX (R)) resin can remove a majority of hydrophilic compounds and a significant amount of hydrophobic compounds from biologically treated secondary effluent within a short contact time of 20 min. It removed a majority of small mol
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.
Smith, P.J., Vigneswaran, S., Ngo, H., Nguyen, H.T. & Ben-Aim, R. 2006, 'Application of an automation system and a supervisory control and data acquisition (SCADA) system for the optimal operation of a membrane adsorption hybrid system', Water Science And Technology, vol. 53, no. 4-5, pp. 179-184.
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The application of automation and supervisory control and data acquisition (SCADA) systems to municipal water and wastewater treatment plants is rapidly increasing. However, the application of these systems is less frequent in the research and developmen
Shon, H., Vigneswaran, S., Kim, I., Cho, J. & Ngo, H. 2006, 'Fouling of ultrafiltration membrane by effluent organic matter A detailed characterization using different organic fractions in wastewater', Journal Of Membrane Science, vol. 278, no. 1-2, pp. 232-238.
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Membrane fouling caused by hydrophobic (HP), transphilic (TP), and hydrophilic (HL) fractions in biologically treated sewage effluent (BTSE) are still not well understood. Some researches reported that the HP fraction (humic substances) were the major pr
Yadav, N.N., Maheswaran, S.M., Shutthanandan, V., Thevuthasan, S., Hart, T.R., Ngo, H. & Vigneswaran, S. 2006, 'Comparison of analytical techniques for analysis of arsenic adsorbed on carbon', Water Quality Research Journal Of Canada, vol. 41, no. 2, pp. 185-189.
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Activated carbon (AC) has been used extensively to treat arsenic-contaminated groundwater for a number of years. To date, attempts to quantify directly the amount of arsenic removed by the activated carbon using nondestructive methods has been limited. H
Smith, P.J., Vigneswaran, S., Ngo, H., Nguyen, H.T. & Aim, R.B. 2006, 'A New Approach to backwash initiation in Membrance Systems', Journal of Membrane Science, vol. 278, no. 1-2, pp. 381-389.
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Yadav, N.N., Maheswaran, S.M., Shutthanandan, V., Thevuthasan, S., Ngo, H. & Vigneswaran, S. 2006, 'Quantification of Arsenic in activated carbon using particle induced X-ray emission', Nuclear Instruments and Methods in Physics Research B, vol. 251, no. 1, pp. 191-196.
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To date, the trace elemental analysis of solids with inhomogencous internal structure has been limited, particularly in the case of adsorbents. High-energy ion beam based particle induced X-ray emission (PIXE) is an ideal analytical too] suitable for sim
Shon, H., Vigneswaran, S., Ngo, H., Johnston, A.J., Kim, I.S. & Cho, J. 2006, 'Performance of Flocculation and Adsorption Pretreatments to Ultrafiltration of Biologically Treated Sewage Effluent: the Effect of Seasonal Variations', Separation Science and Technology, vol. 41, no. 16, pp. 3585-3596.
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The effect of seasonal variations on ultrafiltration (UF) following pretreatment was investigated in terms of organic removal, removal of fraction, and molecular weight (MW) distribution. The MW range of effluent organic matter (EfOM) in biologically treated sewage effluent during winter (BTSE-W) consisted of large MW. However, the MW ranged from 3000 to 200 daltons in biologically treated sewage effluent in the summer (BTSE-S). During filtration experiments of BTSE-S, the UF NTR 7410 filter showed rapid flux decline with time without pretreatment. FeCl3 flocculation removed the hydrophobic (HP) and hydrophilic (HL) fractions with different trends. In winter the HP fraction was removed up to 68.5%, whereas during the summer season, the HL fraction was removed by up to 59.8%. Flocculation removed large MW organics together with small MW, while PAC removed the majority of small MW organics. The flux decline with adsorption was also more severe than that with flocculation. Considering MW distribution, when large MW was removed by flocculation, the flux decline was minimized, whereas PAC adsorption which removed small MW still decreased the permeate flux.
Areerachakul, N., Shon, H., Vigneswaran, S. & Ngo, H. 2006, 'Photocatalytic hybrid system in degradation of herbicide (metsulfuron-methyl)', Water Science & Technology: Water Supply, vol. 6, no. 2, pp. 109-114.
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Photocatalytic oxidation is becoming an emerging technology in water and wastewater Photocatalysis often leads to complete degradation of organic pollutants without any need for chemicals. this study, the removal of the herbicide metsulfuron-methyl (MM)
Smith, P.J., Shon, H., Vigneswaran, S., Ngo, H. & Nguyen, H.T. 2006, 'Productivity enhancement in a cross-flow ultrafiltration membrane system through automated de-clogging operations', Journal Of Membrane Science, vol. 280, no. 1-2, pp. 82-88.
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A membrane system only has a limited operational lifetime, whereby it becomes so severely fouled that continued operation must be stopped. In the cross-flow configuration of membrane filtration of wastewater, both increased cross-flow velocities and decr
Nguyen, V., Vigneswaran, S., Ngo, H., Pokhre, D. & Viraraghavan, T. 2006, 'Iron-coated sponge as effective media to remove arsenic from drinking water', Water Quality Research Journal Of Canada, vol. 41, no. 2, pp. 164-170.
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Arsenic (As) contamination in drinking water is a serious problem in a number of countries in the world, especially in small communities and developing countries. Arsenic is related to many health diseases. Several technologies such as coagulation, adsor
Smith, P.J., Shon, H.K., Vigneswaran, S., Ngo, H.H. & Nguyen, H. 2006, 'Productivity enhancement in a cross-flow ultrafiltration membrane system through automated de-clogging operations', Journal of Membrane Science, vol. 280, no. 1-2, pp. 82-88.
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A membrane system only has a limited operational lifetime, whereby it becomes so severely fouled that continued operation must be stopped. In the cross-flow configuration of membrane filtration of wastewater, both increased cross-flow velocities and decreased operational transmembrane pressures can be used to decrease membrane fouling and extend the life cycle of the membrane separation process. The study found that an optimised usage of two de-clogging techniques, with a 1 h production period followed by a 1 min relaxation period and then a 1 min high cross-flow rate period, resulted in a net productivity increase of 14.8%. The study involved a detailed investigation into the utilization of two automated cleaning techniques to reduce fouling problems encountered when cross-flow membrane systems are operated with high permeate flux rates. The two cleaning techniques studied were periodic membrane relaxation and a periodic high rate cross-flow. During both the relaxation and high rate cross-flow periods, permeate production was stopped. This results in an operational loss in productivity. When each cleaning technique was operated individually, there was a net productivity decrease of 0.7%, due to the 3.2% operational loss due to cleaning technique being implemented. The system was developed using a Programmable Logic Controller (PLC) and a Supervisory Control and Data Acquisition (SCADA) system to accurately control and monitor the process. &copy; 2006 Elsevier B.V. All rights reserved.
Shon, H., Vigneswaran, S., Ngo, H., Kim, I.S. & Ben Aim, R.M. 2005, 'Foulant Characterization of the NF Membranes with and without Pretreatment of Biologically Treated Wastewater', Water Science And Technology, vol. 51, no. 6-7, pp. 277-284.
In this study, different pretreatment methods such as ferric chloride (FeCl3) flocculation and powdered activated carbon (PAC) adsorption were evaluated in terms of their capability in removing effluent organic matter (EfOM) and the characteristics of the foulants on the NF membranes. A detailed experiment was conducted with two NF membranes (NTR 729HF with MWCO 700 daltons and LF 10 with MWCO 200 daltons). With pretreatment, the concentration of organic matter on the membranes decreased to 5.67110+3 (NTR 729HF) and 4.94010+3 (LF 10) mg EfOM/cm2 of membrane from 6.37210+3 (NTR 729HF) and 4.97910+3 (LF 10) mg EfOM/cm2 of membrane. The MW of the solute fraction of biologically treated sewage effluent (BTSE) ranged from 250 daltons to about 3573 (the most important being 250-520 daltons). The weight-averaged MW values of the foulants on the NTR 729HF membrane reduced from 304 daltons without pre-treatment to 208 daltons with pretreatment. In the case of EfOM, the small molecules (MW 300 to 500 daltons) are mainly responsible for the membrane fouling. Thus, the MW distribution of organic matter in the effluent and in the foulant can be used as a representative tool to evaluate the efficiency of pretreatment and NF and in the selection of their operating conditions.
Chiemchaisri, C., Chiemchaisri, W., Kornboonraksa, T., Dumrongsukit, C., Threedeach, S., Ngo, H. & Vigneswaran, S. 2005, 'Particle and microorganism removal in floating plastic media coupled with microfiltration membrane for surface water treatment', Water Science And Technology, vol. 51, no. 10, pp. 93-100.
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Floating plastic media followed by hollow fiber microfiltration membrane was applied for surface water treatment. The performance of the system in terms of particle and microorganisms was investigated. The floating filter was examined at different filtra
Shon, H., Vigneswaran, S., Ngo, H., Kim, I. & Ben Aim, R.M. 2005, 'Foulant characterization of the NF membranes with and without pretreatment of biologically treated wastewater', Water Science And Technology, vol. 51, no. 6-7, pp. 277-284.
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In this study, different pretreatment methods such as ferric chloride (FeCl3) flocculation and powdered activated carbon (PAC) adsorption were evaluated in terms of their capability in removing effluent organic matter (EfOM) and the characteristics of th
Shon, H., Vigneswaran, S., Ben Aim, R.M., Ngo, H., Kim, I.S. & Cho, J. 2005, 'Influence of flocculation and adsorption as pretreatment on the fouling of ultrafiltration and nanofiltration membranes: Application with biologically treated sewage effluent', Environmental Science & Technology, vol. 39, no. 10, pp. 3864-3871.
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Membrane fouling is a critical limitation on the application of membranes to wastewater reuse. This work aims to understand the fouling phenomenon which occurs in ultrafiltration (UF; 17500 molecular weight cutoff (MWCO)) and nanofiltration (NF; 250 MWCO
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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Shon, H., Vigneswaran, S., Kim, H., Ngo, H. & Park, N. 2005, 'Comparison of nanofiltration with flocculation - microfiltration - photocatalysis hybrid system in dissolved organic matter removal', Filtration: International Journal for Filtration and Separation, vol. July, pp. 215-221.
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In this research, a NTR 729HF nanofiltration (NF) membrane was employed to remove synthetic organic matter (SOM) from wastewater. NF alone led to a removal of 92.4% of dissolved organic carbon (DOC). The performance of NF was compared with that of a microfiltration (MF) hybrid system consisting of FeCl3 flocculation, MF and photocatalysis. Flocculation and microfiltration followed by photocatalysis led to more than 96% dissolved organic carbon (DOC) removal. A detailed molecular weight (MW) distribution study of organic matter indicated that the photocatalysis initially breaks the large MW organics and then the small MW organics were removed by a photoreactor process. Flocculation with an optimum dose of FeCl3 (68 mg/L as FeCl3) gave rise to the highest removal of organics including small MW organics. The small MW organics remaining after the treatment of flocculation could successfully be removed by photocatalysis.
Shon, H., Vigneswaran, S., Ngo, H. & Aim, R.B. 2005, 'Is semi-flocculation effective as pretreatment to ultrafiltration in wastewater treatment?', Water Research, vol. 39, no. 1, pp. 147-153.
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In this study, ferric chloride (FeCl3) flocculation was used as a pretreatment to ultrafiltration (UF) in treating synthetic wastewater containing synthetic organic matter (SOM). The effect of flocculant dose was studied in terms of organic removal and m
Smith, P.J., Vigneswaran, S., Ngo, H., Ben-Aim, R. & Nguyen, H.T. 2005, 'Design of a generic control system for optimising back flush durations in a submerged membrane hybrid reactor', Journal Of Membrane Science, vol. 255, no. 38749, pp. 99-106.
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Organic fouling on the membrane can be minimised through powdered activated carbon (PAC) usage in the submerged membrane reactor to adsorb dissolved organic matter and reduce direct organic loading on the membrane. However, fouling cannot be totally alle
Shon, H., Vigneswaran, S., Ngo, H. & Kim, J.K. 2005, 'Chemical coupling of photocatalysis with flocculation and adsorption in the removal of organic matter', Water Research, vol. 39, no. 12, pp. 2549-2558.
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An experimental investigation was made to study the effects of chemical coupling of flocculation and adsorption with photocatalysis in treating persistent organic pollutants in wastewater. The photocatalysis alone showed initial reverse reaction when tit
Shon, H.K., Vigneswaran, S., Ngo, H.H. & Aim, R.B. 2005, 'Is semi-flocculation effective as pretreatment to ultrafiltration in wastewater treatment?', WATER RESEARCH, vol. 39, no. 1, pp. 147-153.
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Shon, H., Vigneswaran, S., Kim, I.S., Cho, J. & Ngo, H. 2004, 'The effect of pretreatment to ultrafiltration of biologically treated sewage effluent: a detailed effluent organic matter (EfOM) characterization', Water Research, vol. 38, pp. 1933-1939.
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Shim, W.G., Chaudhary, D.S., Vigneswaran, S., Ngo, H., Lee, J.W. & Moon, H. 2004, 'Mathematical modeling of granular activated carbon (GAC) biofiltration system', Korean Journal Of Chemical Engineering, vol. 21, no. 1, pp. 212-220.
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In this study, a mathematical model of a fixed bed Granular Activated Carbon (GAC) biofiltration system was developed to predict the organic removal efficiency of the filter. The model consists of bulk transportation, adsorption, utilization, and biodegradation of organics. The variation of the specific surface area due to biofilm growth and the effect of filter backwash were also included in the model. The intrapellet diffusion and the diffusion of substrate in the biofilm were described by linear driving force approximation (LDFA) method. Biodegradation of organics was described by Monod kinetics. Sips adsorption isotherm was used to analyze the initial adsorption equilibrium of the system. The model showed that the organic removal efficiency of the biofilter greatly depends on the parameters related to the biological activities such as the maximum rate of substrate utilization (kmax) and biomass yield (Y) coefficients. Parameters such as suspended cell concentration (Xs) and decay constant (Kd) had little effects on the model simulation results. The filter backwash also had no significant impact on the performance of the biofilter.
Smith, P.J., Vigneswaran, S., Ngo, H., Ben-Aim, R. & Nguyen, H.T. 2004, 'Investigation of Membrane De-Clogging Techniques in the Submerged Filtration Absorption Hybrid System (SMFAHS)', Fluid/Particle Separation Journal, vol. 16, no. 2, pp. 165-173.
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Vigneswaran, S., Shon, H., Boothanon, H., Ngo, H. & Ben-Aim, R. 2004, 'Membrane-flocculation-adsorption Hybrid System in Wastewater Treatment: Micro and Nano Size Organic Matter Removal', Water Science and Technology, vol. 50, no. 12, pp. 265-271.
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Nguyen, V., Vigneswaran, S., Ngo, H., Pokhrel, D. & Viraraghavan, T. 2004, 'Iron Coated Sponge In Arsenic Removal', Fluid/Particle Separation Journal, vol. 16, no. 2, pp. 175-184.
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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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Hoang, T., Shon, H., Chaudhary, D.S., Vigneswaran, S. & Ngo, H. 2004, 'Granular Activated Carbon (GAC) Biofilter For Low Strength Wastewater Treatment', Fluid/Particle Separation Journal, vol. 16, no. 2, pp. 185-191.
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Nguyen, V., Chaudhary, D.S., Ngo, H. & Vigneswaran, S. 2004, 'Arsenic in water: Concerns and treatment technologies', Journal of Industrial and Engineering Chemistry, vol. 10, pp. 337-348.
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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.
Shon, H., Vigneswaran, S., Kim, I.S., Cho, J. & Ngo, H. 2004, 'The effect of pretreatment on the fouling of membranes: application in biologically treated sewage effluent', Journal Of Membrane Science, vol. 234, no. 1-2, pp. 111-120.
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Reuse of wastewater can help in maintaining environmental quality and relieving the unrelenting pressure on conventional and natural freshwater sources. Membrane processes find an important place in the wastewater treatment for reuse. Nonetheless, reverse osmosis (RO) and nanofiltration (NF), i.e. non-porous membranes require higher operational costs and energy. Thus, in this research NTR 7410 ultrafiltration (UF) membrane which is porous was used without and with pretreatment to treat biologically treated sewage effluent (BTSE). Four different pretreatment methods, namely, ferric chloride (FeCl3) flocculation, powdered activated carbon (PAC) adsorption, flocculation followed by adsorption, and granular activated carbon (GAC) biofilter were used in this study to compare their relative merits. Experimental results indicate that the most suitable pretreatment was flocculation followed by adsorption leading to a total organic carbon (TOC) removal of 90%. To assess the suitability of the membranes, it is important to conduct a detailed membrane characterization. The fouled NTR 7410 membrane surface was analyzed in terms of contact angle, zeta potential, attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), flux decline, and TOC removal. The contact angle of the fouled membrane surface was lower than that of the clean membrane surface. This suggests that the majority of the foulants may have been the hydrophilic organic compounds such as polysaccharides, urea, etc. which are the extracellular enzyme of microorganisms in BTSE
Chiemchaisri, C., Panchawaranon, C., Rutchatanunti, S., Kludpiban, A., Ngo, H. & Vigneswaran, S. 2003, 'Development of floating plastic media filtration system for water treatment and wastewater reuse', Journal Of Environmental Science And Health Part A-toxic/hazardous Substances & Environmental Engineering, vol. 38, no. 10, pp. 2359-2368.
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Chaudhary, D.S., Vigneswaran, S., Ngo, H., Kim, S.H. & Moon, H. 2003, 'Effects of biodegradation and background inorganic substances on granular activated carbon adsorption of wastewater', Separation Science And Technology, vol. 38, no. 11, pp. 2515-2531.
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Background inorganic substances are thought to disrupt the adsorption process used in wastewater treatment systems. In this study, a low-strength synthetic wastewater was investigated for biodegradation and adsorption onto granular activated carbon, with and without the presence of background inorganic compounds. Overall, organic compounds in the synthetic wastewater underwent slow biodegradation, but when a solution was prepared with only one or two individual organic components present in the wastewater, biodegradation ceased. This effect was noticed both in the presence and absence of inorganic compounds. The association theory was found to describe the overall adsorption equilibrium of the system better than the more commonly used Freundlich isotherm. The isotherm patterns of the synthetic wastewater indicated that the dissolved inorganic substances had unfavorable effects on the adsorption of dissolved organic substances.
Chaudhary, D.S., Vigneswaran, S., Jegatheesan, V., Ngo, H., Moon, H., Shim, W.G. & Kim, S.H. 2003, 'Granular activated carbon (GAC) adsorption in tertiary wastewater treatment: experiments and models', Water Science And Technology, vol. 47, no. 1, pp. 113-120.
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Chaudhary, D.S., Vigneswaran, S., Ngo, H., Kim, S.H. & Moon, H. 2003, 'Comparison of Association Theory and Freundlich Isotherm For Describing Granular Activated Carbon Adsorption of Secondary Sewager Effluent', Journal of Environmental Engineering and Science, vol. 2, no. 2, pp. 111-118.
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Chaudhary, D.S., Vigneswaran, S., Ngo, H., Shim, W.G. & Moon, H. 2003, 'Granular Activated Carbon (GAC) Biofilter for Low Strength Wastewater', Environmental Engineering Research, vol. 8, no. 4, pp. 184-192.
Chaudhary, D.S., Vigneswaran, S., Ngo, H., Shim, W.G. & Moon, H. 2003, 'Biofilter in Water and Wastewater Treatment', Korean Journal of Chemical Engineering, vol. 20, no. 6, pp. 1054-1065.
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Ngo, H., Jegatheesan, V. & Vigneswaran, S. 2003, 'High Rate Filtration Using Bouyant Medium: Experiments and Mathematical Models', Water Intelligence Online, vol. N/A, no. NA, pp. 1-9.
Vigneswaran, S., Chaudhary, D.S., Ngo, H., Shim, W.G. & Moon, H. 2003, 'Application of a PAC-membrane hybrid system for removal of organics from secondary sewage effluent: Experiments and modelling', Separation Science And Technology, vol. 38, no. 10, pp. 2183-2199.
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As world supplies of clean, fresh water come under increasing pressure and the need for water reuse rises, membrane technology is becoming increasingly important as a possible solution. However, membrane fouling is a major obstacle to the successful operation of the membrane process in wastewater treatment. In this study, a submerged hollow-fiber membrane with powdered activated carbon (PAC) adsorption was investigated for the removal of organics from secondary sewage effluent from a sewage treatment plant. The use of PAC in the membrane system was found to be very effective, not only in removing refractory organics, but also in reducing membrane clogging. A simple mathematical model was developed to predict the effluent quality [in terms of total organic carbon (TOC)] of the submerged membrane-adsorption hybrid system.
Kim, S.H., Ngo, H., Chaudhary, D.S., Kim, J.C., Vigneswaran, S. & Moon, H. 2002, 'Characterisation procedure for absorption of DC (Dissolved Organic Carbon) from synthetic waste water', Korean Journal of Chemical Engineers, vol. 19, no. 5, pp. 888-894.
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Chapman, H.A., Vigneswaran, S., Ngo, H., Dyer, S. & Ben Aim, R.M. 2002, 'Pre-flocculation of secondary treated wastewater in enhancing the performance of microfiltration', Desalination, vol. 146, no. N/A, pp. 367-372.
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Thiruvenkatachari, R., Ngo, H., Hagare, P., Vigneswaran, S. & Ben Aim, R.M. 2002, 'Flocculation-cross-flow microfiltration hybrid system for natural organic matter (NOM) removal using hematite as a flocculent', Desalination, vol. 147, no. N/A, pp. 83-88.
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Jegatheesan, V., Lamsal, P.R., Visvanathan, C., Ngo, H. & Shu, L. 2002, 'Effect of natural organic compounds on the removal of organic carbon in coagulation and flocculation processes', Water Science & Technology: Water Supply, vol. 2, no. 5,6, pp. 473-479.
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Ngo, H., Vigneswaran, S., Hu, J.Y., Thirunavukkarasu, O. & Viraraghavan, T. 2002, 'A comparison of conventional and non-conventional treatment technologies on arsenic removal from water', Water Science & Technology: Water Supply, vol. 2, no. 5,6, pp. 119-125.
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Kim, S.H., Bidkar, A., Ngo, H., Vigneswaran, S. & Moon, H. 2001, 'Adsorption and mass transfer characteristics of Metsulfuron-Methyl on activated carbon', Korean Journal of Chemical Engineering, vol. 18, no. 2, pp. 163-169.
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Hagare, P., Thiruvenkatachari, R. & Ngo, H. 2001, 'A feasibility study of using haematite to remove dissolved organic carbon in water treatment', Separation Science and Technology, vol. 3, no. 3, pp. 2547-2560.
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Hagare, P., Thiruvenkatachari, R. & Ngo, H.H. 2001, 'A feasibility study of using hematite to remove dissolved organic carbon in water treatment', SEPARATION SCIENCE AND TECHNOLOGY, vol. 36, no. 11, pp. 2547-2559.
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Ngo, H., Vigneswaran, S., Kim, S.H., Bidkar, A. & Moon, H. 2000, 'Microfiltration - absorption hybrid system in organic removal from water', Water Science and Technology, vol. Volume 41, no. 0, pp. 51-57.
Vigneswaran, S., Ngo, H., Hashimoto, K., Hasegawa, T. & Watanabe, Y. 2000, 'High Rate Floating Medium Flocculation-filtration With In-line Polysilicato-iron (PSI) Addition', Environmental Technology, vol. 21, no. 3, pp. 317-325.
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The performance of a high rate floating medium flocculation-filtration system with an in-line addition of a silica-polymer compound, namely polysilicato-iron (PSI) has been investigated for water treatment. This study is intended to investigate the applicability of PSI as a sole flocculant or as a combined flocculant with an organic polymer in the downflow floating medium filter. The filter system was operated at a high loading rate of up to 60 m3 m-2 h-1. Filter column experiments were conducted at different PSI doses, filtration rates, filter depths and buoyant medium types and sizes. Results showed the filter system was able to yield uniform and filterable flocs (15 - 20 &Acirc;&micro;m), even at a very high filtration rate of 60 m-3 h-1, through out the filter run time of 4 hours. Better filter performance was obtained when: (i) polystyrene beads of 1.9 mm diameter or polypropylene beads of 3.8 mm diameter; (ii) an in-line single dosage of 2.5 mg l-1 PSI; (iii) in-line combined dosages of 1.5 mg l-1 PSI and 0.4-0.6 mg l-1 organic polymers (cationic polyacrylamides, cationic polystyrene or Pollyallylamine hydrochloride) were used. When PSI was introduced as a sole flocculant, more than 90% turbidity was removed from a 54 NTU artificial kaolin clay suspension at a filtration rate of 30 m-3 m-2h-1 with very low headloss development. Greater removals were achieved when SIF was used in combination with a polymer (e.g.greater than 95% turbidity removal). Frequent (once in every 90 minutes) but short duration backwash (less than 60 s) by air and water enables the system to maintain a superior effluent quality (e.g. turbidity less than 1 NTU) during the filter run. Backwash water requirement was very low (approximately 1%-2% of filtered water production). A lower amount of sludge was produced from the filter in case of combined PSI and organic polymer coagulant addition.
Vigneswaran, S., Kwon, D., Ngo, H. & Hu, J. 2000, 'Improvement of microfiltration perfromance in water treatment: Is critical flux, a viable solution?', Water Science and Technology, vol. Volume 41, no. 0, pp. 309-310.
Vigneswaran, S., Ngo, H. & Lee, K.L. 1999, 'Effluent recycle and waste minimization in prawn farm effluent', Journal of Cleaner Production, vol. 7, no. 2, pp. 121-126.
Prawn farms withdraw huge quantities of sea water and discharge 5&acirc;30% of it back to the estuary during water exchange process. The effluent from the prawn ponds contains large quantities of solids, nitrogen, phosphorus and algae and it cannot be discharged into the estuary or ocean without proper effluent treatment. Sedimentation could form a partial treatment system. In this study, about 28&acirc;38% removal was achieved at an overflow rate of 40 m3/m2.d. Because of low loading, it requires a large area. Co-culture systems may be technically feasible but it is difficult to control the prawns growth. Considering the water quantity requirement, it is necessary to design a high rate treatment system to treat the effluent and recycle it in the system. A high rate floating medium filter led to 68% removal of suspended solids at 20 m3/m2.h and with a depth of 1.2 m. The removal efficiency increased when flocculant was added. A combined downflow floating medium and sand filter gave rise to almost 90% solids and phosphorus removal. Another way is to control the nutrient discharge by optimizing the feed and reducing its waste. &Atilde; 1999 Elsevier Science Ltd. All rights reserved.
Peiris, P., Bailey, J., Ngo, H. & Vigneswaran, S. 1998, 'Bacterial Removal From Secondary Sewage Effluent By A Combined Downflow Floating Medium Flocculatorperprefilter And Sand Filter', Indian Journal Of Engineering And Materials Sciences, vol. 5, no. 4, pp. 217-222.
semi pilot-scale study conducted with the combined downflow floating medium flocculatorperprefilter and sand filter indicated that, it is an effective filter system for removing bacteria from the secondary sewage effluent. Since the filter system can rem
Ngo, H. & Vigneswaran, S. 1998, 'Process Optimisation Of A Combined System Of Floating Medium And Sand Filter In Prawn Farm Effluent Treatment', Water Science And Technology, vol. 38, no. 4-5, pp. 87-93.
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A treatment technology known as "a combined system of floating medium and sand filter (FMSF)" was developed and tested successfully with prawn farm effluent. This system has a remarkable techno-economical advantages. Laboratory and semi pilot-scale studies were carried out to optimise the filter bed depth, backwash method and other operating conditions. The dewatering characteristics of sludge from filter backwash was also analysed. The filter was operated at a high rate. The experimental results indicated that: (i) in case of no in-line chemical addition, the smaller ratio between floating medium and sand filter depth gave rise better filter performance. At the filtration rate of 7.5 - 20 m3/m2.h and with an in-line chemical addition, the suitable depth of floating medium varied from 400-1000 mm for a sand filter depth of 400 mm; (ii) frequent (once in every 90-120 minutes) but short duration of backwash (not more than 60 seconds) was found to be suitable. During the backwash, the water and air were sent for 30 seconds in upward direction and then followed with upflow of water for another 30 seconds. Backwash water amount comprised only 1.2-1.8% of the filtered water production. A mechanical backwash system using rotating paddles is a promising alternative for floating medium filter; and (iii) the filterability of the sludge from filter backwash was low in case of no in-line chemical addition (specific resistance, r = 9.34 1010 m/kg) but improved with in-line flocculant addition (r = 3.07 109 - 1.29 1010 m/kg).
Vigneswaran, S., Ngo, H. & Jeyaseelan, J. 1997, 'Application Of Non-conventional Filtration Technologies In Pollution Control', Environmental Monitoring And Assessment, vol. 44, no. 1-3, pp. 231-240.
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Deep bed filtration is becoming increasing important in wastewater treatment particularly in tertiary treatment as stringent water quality standards are emphasized. A detailed pilot-scale filtration study conducted with secondary effluent in a sewage treatment plant indicated that tertiary filtration with prior alum flocculation is capable of producing high quality effluent, particularly an effluent with phosphorus content of less than 0.3 mg/L (Vigneswaran and Ngo, 1994). Main problem of dual media filter has been rapid headloss development thus frequent backwash requirement. To overcome this problem two independent experimental studies were conducted: one with mobile bed filtration (MBF) and the other with combined downflow floating medium flocculator/prefilter (DFF) and coarse sand filter (CSF) system. A semi-pilot scale mobile bed filtration study conducted using oxidation pond effluent indicated that MBF with contact-flocculation arrangement was good in removing COD, T-P and turbidity with practically no headloss development. Sand of 0.6-0.84 nm dia and 50 cm depth was sufficient to reduce the COD and P from 55 mg/L and 4.5 mg/L to 15 mg/L and 0.5 mg/L respectively at a filtration rate of 7.5 m3/m2.h. Another experimental study with combined DFF-CSF system indicated that the DFF with in-line flocculation addition is a good pretreatment unit to reduce the phosphate upto 80-90%. The fact that DFF resulted in uniform filterable-flocs, it can also successfully be used as a static flocculator/prefilter unit. The introduction of DFF on top of a coarse sand filter increased the filter run time and removal efficiency (more 90-95% of NH3-N and T-P removal respectively). Most importantly, the backwashing of this system was achieved with small quantity of water at low backwash indicated that the removal efficiency was also superior with this system apart from the major advantage of low operating cost.
Kwon, D., Vigneswaran, S., Ngo, H. & Shin, H. 1997, 'An Enhancement Of Critical Flux In Crossflow Microfiltration With A Pretreatment Of Floating Medium Flocculatorperprefilter', Water Science And Technology, vol. 36, no. 12, pp. 267-274.
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In this study, use of a combined system of flocculation-microfiltration was assessed for its capability in removing solids and organics. The improvement of flux by the preflocculation was also investigated. The experimental set-up consisted of (i) Millipore flat plate microfiltration module with constant permeate withdrawal arrangement and (ii) a floating medium flocculator/filter consisting of polypropylene beads as a pretreatment. Commercial ferric chloride(FeCl3) was used for flocculation. The purpose of floating medium filter was primarily to produce filterable flocs and also to achieve partial solids and organics removal. The critical flux of kaolin clay suspension of 10 - 100mg/L was measured for membrane of pore size of 0.2m in the presence of 0 - 4mg/L of fulvic acid in the suspension without any pretreatment. The critical flux was found to decrease with the increase in kaolin clay concentration. The results also indicated that there was no significant effect of organic (fulvic acid) concentration on critical flux. The pretreatment of floating medium filter alone without flocculant addition removed 30 - 40% of solids and resulted in a significant improvement of critical flux in crossflow microfiltration. Degree of solids and organic removal and the variation in critical flux were then studied in detail for the preflocculated/filtered kaolin clay suspension in the presence of organics. The pretreatment of flocculation/prefiltration removed approximately 50% of organics while producing uniform microflocs of 13 - 16 m size. In addition, it enhanced the critical flux by 70% and resulted in 30 - 70% of the remaining organic removal in the crossflow microfiltration.
Ngo, H., Vigneswaran, S. & Jegatheesan, V. 1996, 'Mathematical Modelling Of Downflow Floating Medium Filter (dff) With In-line Flocculation Arrangement', Water Science And Technology, vol. 34, no. 3-4, pp. 355-362.
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A laboratory-scale set-up consisting of rapid mixing device and floating medium filter was used to study the use of a downflow floating medium filter (DFF) with an in-line flocculation arrangement as a static flocculator and a prefilter. The semi-empirical mathematical model formulated incorporates flocculation within the filter, particle/floc attachment onto the filter and the detachment of flocs from the medium. The mathematical model for filtration takes into account the expansion of the filter bed. The removal efficiency of DFF and headloss development were successfully simulated for different conditions of filtration velocity, filter depth and influent suspended solids (SS). The values of attachment coefficient ap and headloss coefficient were found to be independent of filtration velocity, filter depth and influent SS concentration.
Ngo, H. & Vigneswaran, S. 1996, 'Application Of Downflow Floating Medium Flocculatorperprefilter (dff) - Coarse Sand Filter (csf) In Nutrient Removal', Water Science And Technology, vol. 33, no. 8, pp. 63-70.
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In this study, the applicability and the advantages of the downflow floating medium filter (DFF) in wastewater treatment were examined. The experimental results indicated that the DFF with in-line fiocculation addition is a good pretreatment unit to reduce phosphorus load (up to 80&acirc;89% removal). The DFF also resulted in uniform filterable-floes of 32&acirc;42 (am throughout the filter run. Thus it can also successfully be used as a flocculator. The backwashing of floating medium was achieved with a small quantity of water and at low backwash velocity. The introduction of floating medium filter bed on top of a coarse sand filter unit (CSF) increased the filter run time and removal efficiency (more than 87 and 94% of NH3-N and T-P removal respectively), particularly at a low filtration rate (5 m3/m2.h).
Ngo, H. & Vigneswaran, S. 1995, 'Application Of Floating Medium Filter In Water And Waste-water Treatment With Contact-flocculation Filtration Arrangement', Water Research, vol. 29, no. 9, pp. 2211-2213.
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Conventional granular filtration, although successfully used in water treatment and tertiary wastewater treatment, suffers from some disadvantages such as limited retention capacity and high energy requirement for backwashing. Use of floating filter medium overcomes these shortcomings especially when direct filters are used in the treatment plants. A laboratory-scale study carried out indicated that the floating medium filter with downflow direct filter arrangement was a good pretreatment unit to reduce the pollutant load in rapid filters used as polishing filter units. Due to its ability to form uniform micro-flocs of the order of 26&acirc;40 &Icirc;&frac14;m throughout the filter run, the floating medium filter can serve as an excellent static flocculator.
Ngo, H., Vigneswaran, S. & Miller, S.C. 1995, 'Optimization Of Direct-filtration - Experiments And Mathematical-models', Environmental Technology, vol. 16, no. 1, pp. 55-63.
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A laboratory-scale set-up consisting of helicoidal flocculator and rapid sand filter was used to study the implication of flocs in direct filtration for optimizing the design parameters. Two different methods, one using a flocculation and filtration mathematical model and other using Ives' filterability number were used to optimize the direct filtration. The results indicated that (i) there is an optimum range of floc size which resulted in prolonged filter run, (ii) alum dose played an important role in floc size and density, (iii) a good compromise between velocity gradient and flocculation time is essential in optimizing the direct filtration performance, and (iv) the optimum filter depth increased with higher filtration rate. The simulation results indicated that a floc size of 62 &Acirc;&micro;m was found to be optimum for direct filtration which corresponded to 2.5 minutes of flocculation time at the velocity gradient values of 26.5 s-1. This optimum value shifted with filter medium size, depth and filtration velocity. On the other hand, Ives' filterability number indicated that a floc size of 57-76 &Acirc;&micro;m was found to be optimum which corresponded to 4.8 - 7.2 minutes of flocculation time and at a velocity gradient values of 33.6 - 79.6 s-1. These methods will help in optimizing the design parameters of direct filtration in a rational manner using minimum number of experiments with the specific raw water and chemicals.
Vigneswaran, S., Ngo, H.H., Maheswaran, S., Ostarcevis, E. & Potter, A. 1995, 'Improved phosphorus and bacterial removal in sewage treatment plants: A pilot-scale study', Water Treatment, vol. 10, no. 1, pp. 75-80.
Studies have shown, superior removal of phosphorus (up to the level of less than 0.03 mg/L in the treatment plant effluent) is essential to the improvement of water quality of Hawkesbury-Nepean River in New South Wales, Australia. But the chemical precipitation presently adopted in the secondary treatment step can only decrease phosphorus level to about 1 mg/L. A detailed pilot-scale filtration study conducted with secondary effluent in a sewage treatment plant indicated that tertiary filtration with a prior alum flocculation is essential in achieving superior B removal. The best results were obtained with sand (ES = 0.85-0.95; U = 1.25-1.50 mm) as filter medium and 4.4 min of preflocculation. Alum at 40 mg/L was found to be the most suitable chemical. Dual media filter also produced comparable effluent quality (although slightly inferior) while leading to longer filter runs.
Waite, T.D., Amal, R., Ngo, H. & Vigneswaran, S. 1993, 'Effects Of Adsorbed Organic-matter On Size, Structure And Filterability Of Iron Oxyhydroxide Flocs', Water Science And Technology, vol. 27, no. 11, pp. 133-142.
The presence of organic matter may modify the nucleation and aggregation process of the oxide flocculants being used in water treatment processes. Such organic induced modifications in floc behaviour may necessitate a variation in treatment process. The effects of adsorbed fulvic acid, a naturally occurring organic acid, on the aggregation and filtration of hematite particles are investigated. Evidence is presented to show that the structure of the aggregates formed in the presence of fulvic acid depends on the aggregation kinetics and the amount of the fulvic acid. The presence of fulvic acid also greatly affects the filter efficiency due in part to the reversal of charge on the particles but also to the variables of particle size and structure. Since the filtration and the removal of these particles depends on their characteristic size, shape and chemical nature, the studies of the aggregation kinetics and the resulting structure of organic influenced particles are relevant to the removal of pollutants from surface waters (A).

Memorandum of Understanding (MOU)

  • Tongji University (State Key Lab. Of Pollution Control and Resource Reuse) and Tianjin Polytechnic University (Stae Key Lab. of Separation Membrane and Membrane Processeses)
  • National Taiwan University (Department of Chemical Engineering)

Collaborative Agreement:

  • Xi'an University of  Architecture and Technology