The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Claudia Pahl-wostl - One of the best experts on this subject based on the ideXlab platform.
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Chapter 2.6:Stakeholder Responsive Research as an Approach to Support Adaptive Integrated Water Management: Examples from the Newater Project
Water System Science and Policy Interfacing, 2009Co-Authors: Claudia Pahl-wostl, Britta Kastens, Ilke Borowski, Darya HirschAbstract:In the past decade, a major change in the rhetoric surrounding water resources management has become evident. The debate is now dominated by an increased awareness of integrated management approaches, taking into account environmental, economic and social considerations, and by the search for strate...
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Assessing Framing of Uncertainties in Water Management Practice
Water Resources Management, 2009Co-Authors: Nicola Isendahl, Art Dewulf, Greet François, Marcela Brugnach, Sabine Möllenkamp, Claudia Pahl-wostlAbstract:Dealing with uncertainties in water management is an important issue and is one which will only increase in light of global changes, particularly climate change. So far, uncertainties in water management have mostly been assessed from a scientific point of view, and in quantitative terms. In this paper, we focus on the perspectives from water management practice, adopting a qualitative approach. We consider it important to know how uncertainties are framed in water management practice in order to develop practice relevant strategies for dealing with uncertainties. Framing refers to how people make sense of the world. With the aim of identifying what are important parameters for the framing of uncertainties in water management practice, in this paper we analyze uncertainty situations described by decision-makers in water management. The analysis builds on a series of “Uncertainty Dialogues” carried out within the Newater project with water managers in the Rhine, Elbe and Guadiana basins in 2006. During these dialogues, representatives of these river basins were asked what uncertainties they encountered in their professional work life and how they confronted them. Analysing these dialogues we identified several important parameters of how uncertainties get framed. Our assumption is that making framing of uncertainty explicit for water managers will allow for better dealing with the respective uncertainty situations.
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Guest Editorial, part of a Special Feature on New Methods for Adaptive Water Management Resources Management in Transition
2009Co-Authors: Claudia Pahl-wostl, Jan Sendzimir, Paul JeffreyAbstract:management under uncertainty). This special feature showcases some of the key work efforts conducted under the umbrella of the Newater project. One major goal of Newater has been the development of a conceptual and methodological framework for the transition of prevailing watermanagement regimes to adaptive ones. Based on this framework, specific approaches and tools have been further developed for practical applications in a number of case studies in Europe (Elbe, Guadiana, Rhine, and Tisza), in Central Asia (Amudarya), and in Africa (Nile and Orange). The emphasis of the work reported in this special feature is on the development of conceptual foundations and methodological innovations.
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Title The relationship between IWRM and Adaptive Water Management
2008Co-Authors: Claudia Pahl-wostl, Jan SendzimirAbstract:Purpose This document has been written to inform the discussions on the relationship between IWRM and Adaptive Water Management in the Newater international platforms. The goal is to develop a joint view on the expected contributions of the Newater project to improving the conceptual foundations and the practical implementation of the IWRM principle
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The Newater Management and Transition Framework — state and development process —
Adaptive and Integrated Water Management, 2008Co-Authors: Claudia Pahl-wostl, Jörn Möltgen, Eva Ebenhoeh, Georg HoltzAbstract:This paper presents the first completed version of the Management and Transition Framework developed in the Newater1 project. The framework is an interdisciplinary conceptual framework supporting the analysis of water systems and management regimes to improve the scientific understanding of system properties and to give practical guidance for the implementation of transition processes towards more adaptive systems. The framework integrates a range of concepts to develop a more coherent understanding of the complexity of water management regimes. Specific emphasis is given to adaptive capacity and learning processes. The framework has been developed in a participatory process involving a wide range of researchers from different disciplines. The framework development process made thus an important contribution to the process of integration within the project.
Claudia Pahlwostl - One of the best experts on this subject based on the ideXlab platform.
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the Newater management and transition framework state and development process
2008Co-Authors: Claudia Pahlwostl, Jörn Möltgen, Eva Ebenhoeh, Georg HoltzAbstract:This paper presents the first completed version of the Management and Transition Framework developed in the Newater1 project. The framework is an interdisciplinary conceptual framework supporting the analysis of water systems and management regimes to improve the scientific understanding of system properties and to give practical guidance for the implementation of transition processes towards more adaptive systems. The framework integrates a range of concepts to develop a more coherent understanding of the complexity of water management regimes. Specific emphasis is given to adaptive capacity and learning processes. The framework has been developed in a participatory process involving a wide range of researchers from different disciplines. The framework development process made thus an important contribution to the process of integration within the project.
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transitions towards adaptive management of water facing climate and global change
Water Resources Management, 2006Co-Authors: Claudia PahlwostlAbstract:Water management is facing major challenges due to increasing uncertainties caused by climate and global change and by fast changing socio-economic boundary conditions. More attention has to be devoted to understanding and managing the transition from current management regimes to more adaptive regimes that take into account environmental, technological, economic, institutional and cultural characteristics of river basins. This implies a paradigm shift in water management from a prediction and control to a management as learning approach. The change towards adaptive management could be defined as “learning to manage by managing to learn”. Such change aims at increasing the adaptive capacity of river basins at different scales. The paper identifies major challenges for research and practice how to understand a transition in water management regimes. A conceptual framework is introduced how to characterize water management regimes and the dynamics of transition processes. The European project Newater project is presented as one approach where new scientific methods and practical tools are developed for the participatory assessment and implementation of adaptive water management.
Harry Seah - One of the best experts on this subject based on the ideXlab platform.
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From R&D to application: membrane bioreactor technology for water reclamation
Water Practice & Technology, 2017Co-Authors: Winson C.l. Lay, Guihe Tao, Yahya Abd Ghani, Charles Lim, Lee Yingjie, Bee Hong Kwok, Kah Seng Lee, Chua Seng Chye, Yuen Long Wah, Harry SeahAbstract:PUB Singapore has been developing the membrane bioreactor (MBR) technology for water reclamation. The MBR technology has significant versatility and can be applied for production of industrial water or combined with reverse osmosis to produce Newater. The MBR technology offers greater opportunity for process intensification and further enhancement to achieve water sustainability. Compared to conventional treatment, MBR is a 3-in-1 solution that combines bioreactor, secondary sedimentation tank and microfiltration/ultrafiltration in one single step. The advantages of MBR include process robustness, superior filtrate quality and compact footprint. Progressing from pilot studies and demonstration testing, the MBR technology is currently implemented at full-scale in Jurong and Changi Water Reclamation Plant. Moving forward, PUB continues to embark on R&D in developing innovative MBR systems for future application that includes the forthcoming Tuas Water Reclamation Plant as part of the Deep Tunnel Sewerage System Phase 2 project. This manuscript provides an overview of R&D initiatives for developing the MBR technology for water reclamation spanning more than a decade at PUB.
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RO brine treatment and recovery by biological activated carbon and capacitive deionization process.
Water Science and Technology, 2011Co-Authors: Guihe Tao, Bala Viswanath, Kiran A. Kekre, Lai Yoke Lee, Say Leong Ong, Harry SeahAbstract:The generation of brine solutions from dense membrane (reverse osmosis, RO or nanofiltration, NF) water reclamation systems has been increasing worldwide, and the lack of cost effective disposal options is becoming a critical water resources management issue. In Singapore, Newater is the product of a multiple barrier water reclamation process from secondary treated domestic effluent using MF/UF-RO and UV technologies. The RO brine (concentrates) accounts for more than 20% of the total flow treated. To increase the water recovery and treat the RO brine, a CDI based process with BAC as pretreatment was tested. The results show that ion concentrations in CDI product were low except SiO2 when compared with RO feed water. CDI product was passed through a RO and the RO permeate was of better quality including low SiO2 as compared to Newater quality. It could be beneficial to use a dedicated RO operated at optimum conditions with better performance to recover the water. BAC was able to achieve 15-27% TOC removal of RO brine. CDI had been tested at a water recovery ranging from 71.6 to 92.3%. CDI based RO brine treatment could improve overall water recovery of Newater production over 90%. It was found that calcium phosphate scaling and organic fouling was the major cause of CDI pressure increase. Ozone disinfection and sodium bisulfite dosing were able to reduce CDI fouling rate. For sustainable operation of CDI organic fouling control and effective organic fouling cleaning should be further studied.
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Capacitive Deionization for RO brine recovery in Newater production
Water Practice & Technology, 2008Co-Authors: Lai Yoke Lee, Guihe Tao, K. Kekre, B. Viswanath, Say Leong Ong, Winson Lay, Harry SeahAbstract:Reverse osmosis (RO) brine from water reclamation facility is a potential untapped water source, provided a feasible and economical treatment process is available to recover this waste stream. Organic and inorganic compounds are two major groups of pollutants in the RO brine. In this study, an integrated treatment scheme consisting of a biological activated carbon (BAC) column and a low pressure Capacitive Deionization (CDI) process was investigated. BAC was used as a pretreatment to remove the organic compounds prior to the inorganic removal using the CDI process. Two empty bed contact times, namely 20 min and 40 min tested in the BAC columns provided similar TOC removal efficiency within the range of 15–21%. High ions removals of more than 85% from the RO brine were achieved in the CDI process when operated with water recovery up to 89%. This study has successfully demonstrated that the integrated BAC with CDI process has high potential to increase water recovery of a water reclamation plant while gaining the advantage of a reduced volume of RO brine for disposal. This system could further contribute to enhancement of sustainable water reclamation practice.
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MBR-RO for high-grade water (Newater) production from domestic used water
Water Practice & Technology, 2006Co-Authors: Guihe Tao, K. Kekre, J.j. Qin, C.l. Ting, B. Viswanath, Harry SeahAbstract:Singapore has been developing new technologies to reclaim water to drinking water standards from domestic used water. The water produced with drinking water standards by dual membrane process is called Newater in Singapore. After the successful pilot study of membrane bioreactor for water reclamation, MBR-RO integrated system was also studied at pilot scale to investigate the new option of producing Newater at a more reliable and economical way. A MBR-RO pilot plant with capacity of 20m3/d was used for this study. Settled domestic used water was used for the feed. The pilot study demonstrated that the MBR offered better synergy between membrane and activated sludge process. The new MBR-RO process could produce equivalent or better high grade water (Newater) and have better resistance to shock loading than the conventional AS-MF/UF-RO from the domestic used water. RO membranes in the MBR-RO process could be operated 30% higher flux than in AS-MF/UF-RO process for Newater production.
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New option of MBR-RO process for production of Newater from domestic sewage
Journal of Membrane Science, 2006Co-Authors: J.j. Qin, Guihe Tao, Bala Viswanath, Kiran A. Kekre, Maung Nyunt Wai, Ting Cui Lee, Harry SeahAbstract:Abstract The membrane bioreactor (MBR), a combination of conventional activated sludge process (ASP) and membrane separation, can produce consistently high quality of effluent from municipal wastewater. Successful pilot studies have already demonstrated the advantages of MBR technology for reclaiming the domestic sewage in Singapore. The objective of this pilot study was to further investigate a new option of the MBR-RO process to produce high grade water directly from domestic sewage. The MBR-RO process was evaluated over 5 months for its ability to produce better quality effluent. Trial runs on various fluxes of the RO membrane were conducted. Comparison of the new MBR-RO process to the conventional ASP-MF-RO process was also made. The results showed that the new MBR-RO process demonstrated the capability of producing the same or more consistent product quality (in terms of TOC, NH4 and NO3) compared to the conventional ASP-MF-RO process in reclamation of domestic sewage. RO membranes in the MBR-RO process could be operated at 22 L m−2 h−1 without CIP during the whole study period of 5 months, which was 30% higher than that (17 L m−2 h−1) in the ASP-UF-RO process for Newater production. RO permeate quality was improved with increasing the membrane flux. It was concluded that the MBR-RO process could be a new option for Newater production.
Yu Liu - One of the best experts on this subject based on the ideXlab platform.
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Development of an integrated aerobic granular sludge MBR and reverse osmosis process for municipal wastewater reclamation.
Science of The Total Environment, 2020Co-Authors: Siyu Wang, Jia Wei Chew, Yu LiuAbstract:Abstract The reclamation of municipal wastewater to obtain high-grade product water is a growing need due to the pressing global water shortage. However, the existing municipal wastewater treatment plants (WWTPs) with the conventional activated sludge process as a core is not a sustainable engineering solution towards future water sustainability. To tackle such an emerging water-wastewater nexus, a ferrous-assisted aerobic granular sludge membrane bioreactor and reverse osmosis (AGSMBR-RO) process was developed for municipal wastewater reclamation. Results show that about 99.9%, 99.7% and nearly 100% of dissolved organic carbon (DOC), ammonium-N and total phosphorus (TP), respectively, could be removed in the ferrous-assisted AGSMBR-RO process, while the product water could meet the typical Newater quality of Singapore with respect to the parameters analysed in this study. Moreover, it was found that an addition of 6 mg/L of ferrous could improve the stability of aerobic granular sludge (AGS) through the coagulation and flocculation of suspended flocs as well as phosphorus removal. These in turn led to reduced membrane fouling in both AGSMBR and RO units. Consequently, the proposed process is a promising alternative for municipal wastewater reclamation.
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Environmental sustainability: a pressing challenge to biological sewage treatment processes
Current Opinion in Environmental Science & Health, 2019Co-Authors: Xiaoyuan Zhang, Hang Liu, Meng Zhang, Yu LiuAbstract:Abstract The operation of current biological sewage treatment processes is mainly based on the bio-oxidation principle with the input of substantial amount of energy for oxidation of sewage COD and ammonia. Meanwhile, an extremely large quantity of waste sludge is inevitably produced through biological conversion of soluble chemical oxygen demand (COD) to biomass. With tightened effluent discharge standards worldwide, upgrading of the current mainstream biological process with advanced treatment units appears necessary, while making the whole system highly complicated and costly with enlarged footprint. In such a situation, the sewage treatment philosophy has been seriously challenged by its environmental sustainability. Therefore, this article proposes that A-B process enabling direct capture of wastewater chemical energy should be considered as a feasible option toward energy self-sufficient sewage reclamation with minimized sludge production. Furthermore, a conceptual integrated anaerobic membrane bioreactor with reverse osmosis system is elucidated for reclaiming sewage to Newater-like product water, and it may offer a new avenue to overcome the challenges faced in the current sewage treatment plants.
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Technology feasibility and economic viability of an innovative integrated ceramic membrane bioreactor and reverse osmosis process for producing ultrapure water from municipal wastewater
Chemical Engineering Journal, 2019Co-Authors: Siyu Wang, Hang Liu, Huifang Sun, Meng Zhang, Yu LiuAbstract:Abstract Nowadays, it has been widely accepted that the production of ultrapure water (e.g. Newater in Singapore) from municipal wastewater reclamation is a promising alternative to alleviate the severe water scarcity. However, the current Newater production process is extremely complicated, with intensive excess sludge production and large footprint. To address these emerging issues, an innovative process integrating moving bed ceramic membrane bioreactor (MBCMBR) and reverse osmosis (RO) was developed for reclamation of municipal wastewater to ultrapure product water. In this process, the MBCMBR was developed for simultaneous COD and nitrogen removal, while RO was designed for ultrapure water production. The results obtained under different DO conditions showed that more than 99.7% of COD and 96.7% of total nitrogen were removed in the MBCMBR-RO process. It was demonstrated that the product water could meet the Newater and Chinese Class IV standards in terms of total organic carbon, ammonium, nitrate and phosphate, with an insignificant RO membrane fouling propensity evidenced by a dTMP/dt smaller than 0.06 bar/day. In addition, more than 36% and 60% of reduction in footprint and excess sludge production could be achieved in the proposed integrated process against the current Newater production process. Moreover, the Newater-like product water produced from the MBCMBR-RO process can be safely discharged to any surface water, while it can also be supplied to various industrial sectors at an attractive commercial price. Consequently, this study offers an innovative approach for producing ultrapure water from municipal wastewater with small footprint, less sludge production and remarkable economic viability.
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Performance, membrane fouling control and cost analysis of an integrated anaerobic fixed-film MBR and reverse osmosis process for municipal wastewater reclamation to Newater-like product water
Journal of Membrane Science, 2019Co-Authors: Hang Liu, Siyu Wang, Meng Zhang, Yu LiuAbstract:Abstract To relieve the increasing pressure on water scarcity, reclamation and reuse of municipal wastewater represent a global trend. However, the current process for high-grade reclaimed water production faces increasing pressure because of the intensive energy consumption, excessive sludge generation, highly complicated process configuration and large footprint. To tackle these challenges, an integrated anaerobic fixed-film membrane bioreactor (AnfMBR) and reverse osmosis (RO) process was proposed in this study for municipal wastewater reclamation to high-grade product water. Results showed that the product water of the proposed process could meet the typical Newater quality. As fixed anaerobic biofilms were adopted in the reaction chamber of AnfMBR, the intensity of gas sparging for membrane scouring was significantly reduced due to the low suspended solids (SS) in mixed liquor. It was found that the membrane fouling in AnfMBR was dominated by the cake layer, while biofilms and organic substances were the major components in RO foulants. Compared to the current Newater production process, about 35.7% reduction in total cost could be achieved in the AnfMBR-RO process due to the significantly improved energy efficiency. Consequently, the proposed AnfMBR-RO process appeared to be a promising and feasible alternative to the current municipal wastewater reclamation process.
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An innovative anaerobic MBR-reverse osmosis-ion exchange process for energy-efficient reclamation of municipal wastewater to Newater-like product water
Journal of Cleaner Production, 2019Co-Authors: Hang Liu, Siyu Wang, Meng Zhang, Yu LiuAbstract:Abstract The rapid population growth and urbanization have led to an increasing need on recycle and reuse of municipal wastewater. In the current practice for high-grade reclaimed water production, municipal wastewater was first treated by conventional biological process, and further purified through microfiltration and reverse osmosis. However, such a multi-stage process has received more and more critiques due to the process complexity, intensive energy consumption, excessive sludge production and large footprint. To address these emerging issues, this study evaluated the feasibility of an innovative integrated anaerobic membrane bioreactor (AnMBR)-reverse osmosis (RO)-ion exchange (IE) process for treatment of municipal wastewater to high-grade reclaimed water with high energy efficiency and minimized waste sludge production. In this integrated process, an AnMBR was employed as the lead for energy recovery through direct COD capture, and AnMBR effluent was subsequently reclaimed to Newater-like product water through combined RO and IE. Results showed that nearly 76.8% of influent COD was converted to methane in AnMBR equivalent to 0.41 kWh/m3 wastewater treated, while more than 95% of organic carbon, ammonium, phosphate, major ions and cations in AnMBR effluent were rejected by RO. After further polishing by IE, the product water quality appeared to be comparable or even better than the typical Newater quality in Singapore. This study showed that the integrated AnMBR-RO-IE process could produce Newater-like product water with compact footprint, near-zero sludge production, high operation stability, maximized energy recovery and reduced energy consumption compared to the current process for Newater production from municipal wastewater. It is expected that the proposed process can offer new insights into the direction of future wastewater reclamation.
Kiran A. Kekre - One of the best experts on this subject based on the ideXlab platform.
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RO brine treatment and recovery by biological activated carbon and capacitive deionization process.
Water Science and Technology, 2011Co-Authors: Guihe Tao, Bala Viswanath, Kiran A. Kekre, Lai Yoke Lee, Say Leong Ong, Harry SeahAbstract:The generation of brine solutions from dense membrane (reverse osmosis, RO or nanofiltration, NF) water reclamation systems has been increasing worldwide, and the lack of cost effective disposal options is becoming a critical water resources management issue. In Singapore, Newater is the product of a multiple barrier water reclamation process from secondary treated domestic effluent using MF/UF-RO and UV technologies. The RO brine (concentrates) accounts for more than 20% of the total flow treated. To increase the water recovery and treat the RO brine, a CDI based process with BAC as pretreatment was tested. The results show that ion concentrations in CDI product were low except SiO2 when compared with RO feed water. CDI product was passed through a RO and the RO permeate was of better quality including low SiO2 as compared to Newater quality. It could be beneficial to use a dedicated RO operated at optimum conditions with better performance to recover the water. BAC was able to achieve 15-27% TOC removal of RO brine. CDI had been tested at a water recovery ranging from 71.6 to 92.3%. CDI based RO brine treatment could improve overall water recovery of Newater production over 90%. It was found that calcium phosphate scaling and organic fouling was the major cause of CDI pressure increase. Ozone disinfection and sodium bisulfite dosing were able to reduce CDI fouling rate. For sustainable operation of CDI organic fouling control and effective organic fouling cleaning should be further studied.
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Preliminary study on novel backwash cleaning for reverse osmosis fouling control in water reuse
Water Science & Technology: Water Supply, 2010Co-Authors: J.j. Qin, Kiran A. KekreAbstract:We have demonstrated a novel backwash cleaning technique of direct osmosis (DO)-high salinity (HS) for reverse osmosis (RO) fouling control in water reuse. An UF-RO pilot system was continuously (24-h) operated on site with the secondary effluent as the feed over 4 months. The RO plant was run at 75% recovery and at the membrane flux of 17 l m −2 h −1 (LMH) to simulate the full scale Newater production when DO-HS treatment was conducted once per day and five times per week during the last two months. Permeability of RO membranes as a function of elapse time of the pilot operation was monitored and compared over different durations. Impact of DO-HS treatment on RO product quality in terms of TOC and conductivity was investigated. It was concluded that the DO-HS treatment preliminarily demonstrated a benefit to low RO fouling rate by 2.5–4 times in 30–60 days without interruption on RO operation and impact on RO product quality.
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New option of MBR-RO process for production of Newater from domestic sewage
Journal of Membrane Science, 2006Co-Authors: J.j. Qin, Guihe Tao, Bala Viswanath, Kiran A. Kekre, Maung Nyunt Wai, Ting Cui Lee, Harry SeahAbstract:Abstract The membrane bioreactor (MBR), a combination of conventional activated sludge process (ASP) and membrane separation, can produce consistently high quality of effluent from municipal wastewater. Successful pilot studies have already demonstrated the advantages of MBR technology for reclaiming the domestic sewage in Singapore. The objective of this pilot study was to further investigate a new option of the MBR-RO process to produce high grade water directly from domestic sewage. The MBR-RO process was evaluated over 5 months for its ability to produce better quality effluent. Trial runs on various fluxes of the RO membrane were conducted. Comparison of the new MBR-RO process to the conventional ASP-MF-RO process was also made. The results showed that the new MBR-RO process demonstrated the capability of producing the same or more consistent product quality (in terms of TOC, NH4 and NO3) compared to the conventional ASP-MF-RO process in reclamation of domestic sewage. RO membranes in the MBR-RO process could be operated at 22 L m−2 h−1 without CIP during the whole study period of 5 months, which was 30% higher than that (17 L m−2 h−1) in the ASP-UF-RO process for Newater production. RO permeate quality was improved with increasing the membrane flux. It was concluded that the MBR-RO process could be a new option for Newater production.
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TOC removal in reclamation of municipal wastewater by RO
Separation and Purification Technology, 2005Co-Authors: J.j. Qin, Maung Nyunt Wai, Kiran A. KekreAbstract:Abstract A pilot study on total organic carbon (TOC) removal in reclamation of municipal wastewater by RO has been conducted in Singapore. Secondary effluent from final clarifier was used as a feed to the system. RE4040-FL and RE4040-FE RO membranes from Saehan were applied in the study. The pilot results showed that on-line TOC measurements of the RO permeate were in range of 36–66 ppb for RE4040-FL membrane at operating pressure of 60 psi. For RE4040-FE membrane, they were in the range of 32–44 and 30–36 ppb at operating pressure of 70 and 107 psi, respectively. The low TOC level of the reclaimed water does not appear to be reported previously for the application of RO in reclamation of municipal wastewater. TOC and salt rejections of the RE4040-FE membrane were over 99.5 and 97.8%, respectively. The permeate quality and salt rejections of RE4040-FE membrane were better than that of RE4040-FL, which was comparable to High Grade Water (Newater) quality.