The Experts below are selected from a list of 231 Experts worldwide ranked by ideXlab platform
Maria D Kennedy - One of the best experts on this subject based on the ideXlab platform.
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assessing pretreatment effectiveness for particulate organic and Biological Fouling in a full scale swro desalination plant
Membranes, 2021Co-Authors: Almotasembellah Abushaban, Sergio G Salinasrodriguez, Delia Pastorelli, Jan C Schippers, Subhanjan Mondal, Said A Goueli, Maria D KennedyAbstract:In this study, the removal of particulate, organic and Biological Fouling potential was investigated in the two-stage dual media filtration (DMF) pretreatment of a full-scale seawater reverse osmosis (SWRO) desalination plant. Moreover, the removal of Fouling potential in two-stage DMF (DMF pretreatment) was compared with the removal in two-stage DMF installed after dissolved air floatation (DAF) (DAF-DMF pretreatment). For this purpose, the silt density index (SDI), modified Fouling index (MFI), bacterial growth potential (BGP), organic fractions and microbial adenosine triphosphate (ATP) were monitored in the pretreatment processes of two full-scale SWRO plants. Particulate Fouling potential was well controlled through the two stages of DMF with significant removal of SDI15 (>80%), MFI0.45 (94%) and microbial ATP (>95%). However, lower removal of Biological/organic Fouling potential (24–41%) was observed due to frequent chlorination (weekly) of the pretreatment, resulting in low Biological activity in the DMFs. Therefore, neutralizing chlorine before media filtration is advised, rather than after, as is the current practice in many full-scale SWRO plants. Comparing overall removal in the DAF-DMF pretreatment to that of the DMF pretreatment showed that DAF improved the removal of Biological/organic Fouling potential, in which the removal of BGP and biopolymers increased by 40% and 16%, respectively. Overall, monitoring ATP and BGP during the pretreatment processes, particularly in DMF, would be beneficial to enhance Biological degradation and lower bioFouling potential in SWRO feed water.
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seawater reverse osmosis desalination and harmful algal blooms
Desalination, 2015Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, Jan C Schippers, Assiyeh Alizadeh S Tabatabai, Donald M AndersonAbstract:Abstract This article reviews the occurrence of HABs in seawater, their effects on the operation of seawater reverse osmosis (SWRO) plants, the indicators for quantifying/predicting these effects, and the pretreatment strategies for mitigating operational issues during algal blooms. The potential issues in SWRO plants during HABs are particulate/organic Fouling of pretreatment systems and Biological Fouling of RO membranes, mainly due to accumulation of algal organic matter (AOM). The presence of HAB toxins in desalinated water is also a potential concern but only at very low concentrations. Monitoring algal cell density, AOM concentrations and membrane Fouling indices is a promising approach to assess the quality of SWRO feedwater and performance of the pretreatment system. When geological condition is favourable, subsurface intake can be a robust pretreatment for SWRO during HABs. Existing SWRO plants with open intake and are fitted with granular media filtration can improve performance in terms of capacity and product water quality, if preceded by dissolved air flotation or sedimentation. However, the application of advanced pretreatment using ultrafiltration membrane with in-line coagulation is often a better option as it is capable of maintaining stable operation and better RO feed water quality during algal bloom periods with significantly lower chemical consumption.
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improved method for measuring transparent exopolymer particles tep and their precursors in fresh and saline water
Water Research, 2015Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, Jan C Schippers, Yuli Ekowati, Helga N CalixponceAbstract:Transparent exopolymer particles (TEP) and their precursors produced by phyto-/bacterio-planktons in fresh and marine aquatic environments are increasingly considered as a major contributor to organic/particulate and Biological Fouling in micro-/ultra-filtration and reverse osmosis membrane (RO) systems. However, currently established methods which are based on Alcian blue (AB) staining and spectrophotometric techniques do not measure TEP-precursors and have the tendency to overestimate concentration in brackish/saline water samples due to interference of salinity on AB staining. Here we propose a new semi-quantitative method which allows measurement of both TEP and their colloidal precursors without the interference of salinity. TEP and their precursors are first retained on 10 kDa membrane, rinsed with ultra-pure water, and re-suspended in ultra-pure water by sonication and stained with AB, followed by exclusion of TEP-AB precipitates by filtration and absorbance measurement of residual AB. The concentration is then determined based on the reduction of AB absorbance due to reaction with acidic polysaccharides, blank correction and calibration with Xanthan gum standard. The extraction procedure allows concentration of TEP and their pre-cursors which makes it possible to analyse samples with a wide range of concentrations (down to <0.1 mg Xeq/L). This was demonstrated through application of the method for monitoring these compounds in algal cultures and a full-scale RO plant. The monitoring also revealed that concentrations of the colloidal precursors were substantially higher than the concentration of TEP themselves. In the RO plant, complete TEP removal was observed over the pre-treatment processes (coagulation-sedimentation-filtration and ultrafiltration) but the TEP precursors were not completely removed, emphasising the importance of measuring this colloidal component to better understand the role of TEP and acidic polysaccharides in RO membrane Fouling.
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the fate of transparent exopolymer particles tep in seawater uf ro system a pilot plant study in zeeland the netherlands
Desalination and Water Treatment, 2010Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, Rinnert Schurer, Jan C SchippersAbstract:For many years, transparent exopolymer particles (TEP) were found abundant in various marine and freshwater environments, which are currently the main sources of raw water in desalination plants. Just recently, TEP have been identified as a potential foulant capable of causing organic and Biological Fouling in membrane systems. A pilot plant study was conducted to monitor the fate of TEP through the treatment process and to investigate their effects on the operational performance of a seawater UF-RO plant. Using spectrophotometric measurements, particulate (p-TEP > 0.4 mm) and colloidal (0.05 < c-TEP < 0.40 mm) species of TEP were measured at selected points in the plant. TEP monitoring in the raw water recorded a significant increase in both p-TEP and cTEP starting in early spring (March). This period was also marked by an increase of chlorophyll-a and total organic carbon (TOC) mainly attributed to an algal bloom occurrence in the water source. Total TEP from the raw water were partially removed by the micro-strainer (11–21%) and the UF system (*28%). Low Fouling rates in the UF were observed in January and February but severe Fouling were observed in late March and April, coinciding with the increase in TEP level. The severe Fouling was mitigated by applying in-line coagulation before the UF for which irreversible Fouling was significantly reduced. Deposition analyses indicated that significant amounts of p-TEP and c-TEP were deposited in the RO system. However, there was no significant decrease of RO normalized flux during the 4 months of operation in the plant. Long term monitoring is needed to better assess the adverse effects of TEP accumulation in the RO systems.
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the fate of transparent exopolymer particles tep in integrated membrane systems removal through pre treatment processes and deposition on reverse osmosis membranes
Water Research, 2009Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, J C SchippersAbstract:Abstract The abundance of Transparent Exopolymer Particles (TEP) in surface waters has been unnoticed for many years until recently as a potential foulant in reverse osmosis systems. Recent studies indicate that TEP may cause organic and Biological Fouling and may enhance particulate/colloidal Fouling in reverse osmosis membranes. The presence of TEP was measured in the raw water, the pre-treatment processes and reverse osmosis (RO) systems of 6 integrated membrane installations. A spectrophotometric method was used to measure TEP in the particulate size range (>0.40 μm) and was extended to measure TEP in the colloidal size range (0.05–0.40 μm). Ultrafiltration pre-treatment applied in 4 plants, totally removed particulate TEP while microfiltration systems (2 plants) and coagulation/sedimentation/rapid sand filtration systems (3 plants) partially removed this fraction. None of the pre-treatment systems investigated totally removed colloidal TEP. Biopolymer analysis using LC–OCD showed consistency between colloidal TEP and polysaccharide removal by UF pre-treatment and further verified the presence of TEP in the RO feedwater. TEP deposition in the RO system was determined after measuring total TEP concentrations in the RO feed and concentrate. The TEP deposition factors and specific deposition rates indicate that TEP accumulation had occurred in all plants investigated. This observation was verified by an autopsy of RO modules from two RO plants. Further improvement and verification of the (modified) TEP method, in particular the calibration, is necessary so that it can be employed to investigate the role of TEP in the Fouling of RO systems.
Gary L Amy - One of the best experts on this subject based on the ideXlab platform.
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seawater reverse osmosis desalination and harmful algal blooms
Desalination, 2015Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, Jan C Schippers, Assiyeh Alizadeh S Tabatabai, Donald M AndersonAbstract:Abstract This article reviews the occurrence of HABs in seawater, their effects on the operation of seawater reverse osmosis (SWRO) plants, the indicators for quantifying/predicting these effects, and the pretreatment strategies for mitigating operational issues during algal blooms. The potential issues in SWRO plants during HABs are particulate/organic Fouling of pretreatment systems and Biological Fouling of RO membranes, mainly due to accumulation of algal organic matter (AOM). The presence of HAB toxins in desalinated water is also a potential concern but only at very low concentrations. Monitoring algal cell density, AOM concentrations and membrane Fouling indices is a promising approach to assess the quality of SWRO feedwater and performance of the pretreatment system. When geological condition is favourable, subsurface intake can be a robust pretreatment for SWRO during HABs. Existing SWRO plants with open intake and are fitted with granular media filtration can improve performance in terms of capacity and product water quality, if preceded by dissolved air flotation or sedimentation. However, the application of advanced pretreatment using ultrafiltration membrane with in-line coagulation is often a better option as it is capable of maintaining stable operation and better RO feed water quality during algal bloom periods with significantly lower chemical consumption.
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improved method for measuring transparent exopolymer particles tep and their precursors in fresh and saline water
Water Research, 2015Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, Jan C Schippers, Yuli Ekowati, Helga N CalixponceAbstract:Transparent exopolymer particles (TEP) and their precursors produced by phyto-/bacterio-planktons in fresh and marine aquatic environments are increasingly considered as a major contributor to organic/particulate and Biological Fouling in micro-/ultra-filtration and reverse osmosis membrane (RO) systems. However, currently established methods which are based on Alcian blue (AB) staining and spectrophotometric techniques do not measure TEP-precursors and have the tendency to overestimate concentration in brackish/saline water samples due to interference of salinity on AB staining. Here we propose a new semi-quantitative method which allows measurement of both TEP and their colloidal precursors without the interference of salinity. TEP and their precursors are first retained on 10 kDa membrane, rinsed with ultra-pure water, and re-suspended in ultra-pure water by sonication and stained with AB, followed by exclusion of TEP-AB precipitates by filtration and absorbance measurement of residual AB. The concentration is then determined based on the reduction of AB absorbance due to reaction with acidic polysaccharides, blank correction and calibration with Xanthan gum standard. The extraction procedure allows concentration of TEP and their pre-cursors which makes it possible to analyse samples with a wide range of concentrations (down to <0.1 mg Xeq/L). This was demonstrated through application of the method for monitoring these compounds in algal cultures and a full-scale RO plant. The monitoring also revealed that concentrations of the colloidal precursors were substantially higher than the concentration of TEP themselves. In the RO plant, complete TEP removal was observed over the pre-treatment processes (coagulation-sedimentation-filtration and ultrafiltration) but the TEP precursors were not completely removed, emphasising the importance of measuring this colloidal component to better understand the role of TEP and acidic polysaccharides in RO membrane Fouling.
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the fate of transparent exopolymer particles tep in seawater uf ro system a pilot plant study in zeeland the netherlands
Desalination and Water Treatment, 2010Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, Rinnert Schurer, Jan C SchippersAbstract:For many years, transparent exopolymer particles (TEP) were found abundant in various marine and freshwater environments, which are currently the main sources of raw water in desalination plants. Just recently, TEP have been identified as a potential foulant capable of causing organic and Biological Fouling in membrane systems. A pilot plant study was conducted to monitor the fate of TEP through the treatment process and to investigate their effects on the operational performance of a seawater UF-RO plant. Using spectrophotometric measurements, particulate (p-TEP > 0.4 mm) and colloidal (0.05 < c-TEP < 0.40 mm) species of TEP were measured at selected points in the plant. TEP monitoring in the raw water recorded a significant increase in both p-TEP and cTEP starting in early spring (March). This period was also marked by an increase of chlorophyll-a and total organic carbon (TOC) mainly attributed to an algal bloom occurrence in the water source. Total TEP from the raw water were partially removed by the micro-strainer (11–21%) and the UF system (*28%). Low Fouling rates in the UF were observed in January and February but severe Fouling were observed in late March and April, coinciding with the increase in TEP level. The severe Fouling was mitigated by applying in-line coagulation before the UF for which irreversible Fouling was significantly reduced. Deposition analyses indicated that significant amounts of p-TEP and c-TEP were deposited in the RO system. However, there was no significant decrease of RO normalized flux during the 4 months of operation in the plant. Long term monitoring is needed to better assess the adverse effects of TEP accumulation in the RO systems.
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the fate of transparent exopolymer particles tep in integrated membrane systems removal through pre treatment processes and deposition on reverse osmosis membranes
Water Research, 2009Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, J C SchippersAbstract:Abstract The abundance of Transparent Exopolymer Particles (TEP) in surface waters has been unnoticed for many years until recently as a potential foulant in reverse osmosis systems. Recent studies indicate that TEP may cause organic and Biological Fouling and may enhance particulate/colloidal Fouling in reverse osmosis membranes. The presence of TEP was measured in the raw water, the pre-treatment processes and reverse osmosis (RO) systems of 6 integrated membrane installations. A spectrophotometric method was used to measure TEP in the particulate size range (>0.40 μm) and was extended to measure TEP in the colloidal size range (0.05–0.40 μm). Ultrafiltration pre-treatment applied in 4 plants, totally removed particulate TEP while microfiltration systems (2 plants) and coagulation/sedimentation/rapid sand filtration systems (3 plants) partially removed this fraction. None of the pre-treatment systems investigated totally removed colloidal TEP. Biopolymer analysis using LC–OCD showed consistency between colloidal TEP and polysaccharide removal by UF pre-treatment and further verified the presence of TEP in the RO feedwater. TEP deposition in the RO system was determined after measuring total TEP concentrations in the RO feed and concentrate. The TEP deposition factors and specific deposition rates indicate that TEP accumulation had occurred in all plants investigated. This observation was verified by an autopsy of RO modules from two RO plants. Further improvement and verification of the (modified) TEP method, in particular the calibration, is necessary so that it can be employed to investigate the role of TEP in the Fouling of RO systems.
Loreen O Villacorte - One of the best experts on this subject based on the ideXlab platform.
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seawater reverse osmosis desalination and harmful algal blooms
Desalination, 2015Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, Jan C Schippers, Assiyeh Alizadeh S Tabatabai, Donald M AndersonAbstract:Abstract This article reviews the occurrence of HABs in seawater, their effects on the operation of seawater reverse osmosis (SWRO) plants, the indicators for quantifying/predicting these effects, and the pretreatment strategies for mitigating operational issues during algal blooms. The potential issues in SWRO plants during HABs are particulate/organic Fouling of pretreatment systems and Biological Fouling of RO membranes, mainly due to accumulation of algal organic matter (AOM). The presence of HAB toxins in desalinated water is also a potential concern but only at very low concentrations. Monitoring algal cell density, AOM concentrations and membrane Fouling indices is a promising approach to assess the quality of SWRO feedwater and performance of the pretreatment system. When geological condition is favourable, subsurface intake can be a robust pretreatment for SWRO during HABs. Existing SWRO plants with open intake and are fitted with granular media filtration can improve performance in terms of capacity and product water quality, if preceded by dissolved air flotation or sedimentation. However, the application of advanced pretreatment using ultrafiltration membrane with in-line coagulation is often a better option as it is capable of maintaining stable operation and better RO feed water quality during algal bloom periods with significantly lower chemical consumption.
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improved method for measuring transparent exopolymer particles tep and their precursors in fresh and saline water
Water Research, 2015Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, Jan C Schippers, Yuli Ekowati, Helga N CalixponceAbstract:Transparent exopolymer particles (TEP) and their precursors produced by phyto-/bacterio-planktons in fresh and marine aquatic environments are increasingly considered as a major contributor to organic/particulate and Biological Fouling in micro-/ultra-filtration and reverse osmosis membrane (RO) systems. However, currently established methods which are based on Alcian blue (AB) staining and spectrophotometric techniques do not measure TEP-precursors and have the tendency to overestimate concentration in brackish/saline water samples due to interference of salinity on AB staining. Here we propose a new semi-quantitative method which allows measurement of both TEP and their colloidal precursors without the interference of salinity. TEP and their precursors are first retained on 10 kDa membrane, rinsed with ultra-pure water, and re-suspended in ultra-pure water by sonication and stained with AB, followed by exclusion of TEP-AB precipitates by filtration and absorbance measurement of residual AB. The concentration is then determined based on the reduction of AB absorbance due to reaction with acidic polysaccharides, blank correction and calibration with Xanthan gum standard. The extraction procedure allows concentration of TEP and their pre-cursors which makes it possible to analyse samples with a wide range of concentrations (down to <0.1 mg Xeq/L). This was demonstrated through application of the method for monitoring these compounds in algal cultures and a full-scale RO plant. The monitoring also revealed that concentrations of the colloidal precursors were substantially higher than the concentration of TEP themselves. In the RO plant, complete TEP removal was observed over the pre-treatment processes (coagulation-sedimentation-filtration and ultrafiltration) but the TEP precursors were not completely removed, emphasising the importance of measuring this colloidal component to better understand the role of TEP and acidic polysaccharides in RO membrane Fouling.
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algal blooms and membrane based desalination technology
2014Co-Authors: Loreen O VillacorteAbstract:Seawater desalination is rapidly growing in terms of installed capacity (~80 million m3/day in 2013), plant size and global application. An emerging threat to this technology is the seasonal proliferation of microscopic algae in seawater known as algal blooms. Such blooms have caused operational problems in seawater reverse osmosis (SWRO) plants due to clogging and poor effluent quality of the pre-treatment system which eventually forced the shutdown of the plant to avoid irreversible Fouling of downstream SWRO membranes. As more extra large SWRO plants (>500,000 m3/day) are expected to be constructed in the coming years, frequent chemical cleaning (>1/year) of SWRO installations will not be feasible, and more reliable pre-treatment system will be required. To maintain stable operation in SWRO plants during algal bloom periods, pre-treatment using ultrafiltration (UF) membranes has been proposed. This thesis addresses the effect of algal blooms on the operation of UF pre-treatment and SWRO. Experimental investigations demonstrated that marine algal blooms can impact the backwashability of UF and can accelerate Biological Fouling in RO. However, it is unlikely that algae themselves are the main causes of Fouling but rather the transparent exopolymer particles (TEPs) that they produce. To better monitor TEPs, a new method capable of measuring TEP as small as 10 kDa was developed and showed that TEPs can be effectively removed by UF pre-treatment prior to SWRO. This work also demonstrated that although TEPs and other algal-derived material (AOM) are very sticky and can adhere to UF and RO membranes, adhesion can be much stronger on membranes already fouled with AOM. Moreover, a model was developed to predict the accumulation of algal cells in capillary UF membranes which further demonstrated that the role of algal cells in UF Fouling is not as significant as that of AOM and TEPs. Overall, this study demonstrates that better analytical methods and tools are essential in elucidating the adverse impacts of algal blooms in seawater on the operation of membrane-based desalination plants (UF-RO). It also highlighted the importance of developing effective pre-treatment processes to remove AOM from the raw water and reduce the membrane Fouling potential of the feed water for downstream SWRO membranes.
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the fate of transparent exopolymer particles tep in seawater uf ro system a pilot plant study in zeeland the netherlands
Desalination and Water Treatment, 2010Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, Rinnert Schurer, Jan C SchippersAbstract:For many years, transparent exopolymer particles (TEP) were found abundant in various marine and freshwater environments, which are currently the main sources of raw water in desalination plants. Just recently, TEP have been identified as a potential foulant capable of causing organic and Biological Fouling in membrane systems. A pilot plant study was conducted to monitor the fate of TEP through the treatment process and to investigate their effects on the operational performance of a seawater UF-RO plant. Using spectrophotometric measurements, particulate (p-TEP > 0.4 mm) and colloidal (0.05 < c-TEP < 0.40 mm) species of TEP were measured at selected points in the plant. TEP monitoring in the raw water recorded a significant increase in both p-TEP and cTEP starting in early spring (March). This period was also marked by an increase of chlorophyll-a and total organic carbon (TOC) mainly attributed to an algal bloom occurrence in the water source. Total TEP from the raw water were partially removed by the micro-strainer (11–21%) and the UF system (*28%). Low Fouling rates in the UF were observed in January and February but severe Fouling were observed in late March and April, coinciding with the increase in TEP level. The severe Fouling was mitigated by applying in-line coagulation before the UF for which irreversible Fouling was significantly reduced. Deposition analyses indicated that significant amounts of p-TEP and c-TEP were deposited in the RO system. However, there was no significant decrease of RO normalized flux during the 4 months of operation in the plant. Long term monitoring is needed to better assess the adverse effects of TEP accumulation in the RO systems.
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the fate of transparent exopolymer particles tep in integrated membrane systems removal through pre treatment processes and deposition on reverse osmosis membranes
Water Research, 2009Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, J C SchippersAbstract:Abstract The abundance of Transparent Exopolymer Particles (TEP) in surface waters has been unnoticed for many years until recently as a potential foulant in reverse osmosis systems. Recent studies indicate that TEP may cause organic and Biological Fouling and may enhance particulate/colloidal Fouling in reverse osmosis membranes. The presence of TEP was measured in the raw water, the pre-treatment processes and reverse osmosis (RO) systems of 6 integrated membrane installations. A spectrophotometric method was used to measure TEP in the particulate size range (>0.40 μm) and was extended to measure TEP in the colloidal size range (0.05–0.40 μm). Ultrafiltration pre-treatment applied in 4 plants, totally removed particulate TEP while microfiltration systems (2 plants) and coagulation/sedimentation/rapid sand filtration systems (3 plants) partially removed this fraction. None of the pre-treatment systems investigated totally removed colloidal TEP. Biopolymer analysis using LC–OCD showed consistency between colloidal TEP and polysaccharide removal by UF pre-treatment and further verified the presence of TEP in the RO feedwater. TEP deposition in the RO system was determined after measuring total TEP concentrations in the RO feed and concentrate. The TEP deposition factors and specific deposition rates indicate that TEP accumulation had occurred in all plants investigated. This observation was verified by an autopsy of RO modules from two RO plants. Further improvement and verification of the (modified) TEP method, in particular the calibration, is necessary so that it can be employed to investigate the role of TEP in the Fouling of RO systems.
Nidal Hilal - One of the best experts on this subject based on the ideXlab platform.
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reverse osmosis desalination a state of the art review
Desalination, 2019Co-Authors: Muhammad Qasim, Mohamed Badrelzaman, Noora Darwish, Naif A Darwish, Nidal HilalAbstract:Abstract Water scarcity is a grand challenge that has always stimulated research interests in finding effective means for pure water production. In this context, reverse osmosis (RO) is considered the leading and the most optimized membrane-based desalination process that is currently dominating the desalination market. In this review, various aspects of RO desalination are reviewed. Theories and models related to concentration polarization and membrane transport, as well as merits and drawbacks of these models in predicting polarization effects, are discussed. An updated review of studies related to membrane modules (plate and frame, tubular, spiral wound, and hollow fiber) and membrane characterization are provided. The review also discusses membrane cleaning and different pre-treatment technologies in place for RO desalination, such as feed-water pre-treatment and biocides. RO pre-treatment technologies, which include conventional (e.g., coagulation-flocculation, media filtration, disinfection, scale inhibition) and non-conventional (e.g., MF, UF, and NF) are reviewed and their relative attributes are compared. As per the available literature, UF, MF and coagulation-flocculation are considered the most widely used pre-treatment technologies. In addition, this review discusses membrane Fouling, which represents a serious challenge in RO processes due to its significant contribution to energy requirements and process economy (e.g., flux decline, permeate quality, membrane lifespan, increased feed pressure, increased pre-treatment and membrane maintenance cost). Different membrane Fouling types, such as colloidal, organic, inorganic, and Biological Fouling, are addressed in this review. Principles of RO process design and the embedded economic and energy considerations are discussed. In general, cost of water desalination has dropped to values that made it a viable option, comparable even to conventional water treatment methods. Finally, an overview of hybrid RO desalination processes and the current challenges faced by RO desalination processes are presented and discussed.
Jan C Schippers - One of the best experts on this subject based on the ideXlab platform.
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assessing pretreatment effectiveness for particulate organic and Biological Fouling in a full scale swro desalination plant
Membranes, 2021Co-Authors: Almotasembellah Abushaban, Sergio G Salinasrodriguez, Delia Pastorelli, Jan C Schippers, Subhanjan Mondal, Said A Goueli, Maria D KennedyAbstract:In this study, the removal of particulate, organic and Biological Fouling potential was investigated in the two-stage dual media filtration (DMF) pretreatment of a full-scale seawater reverse osmosis (SWRO) desalination plant. Moreover, the removal of Fouling potential in two-stage DMF (DMF pretreatment) was compared with the removal in two-stage DMF installed after dissolved air floatation (DAF) (DAF-DMF pretreatment). For this purpose, the silt density index (SDI), modified Fouling index (MFI), bacterial growth potential (BGP), organic fractions and microbial adenosine triphosphate (ATP) were monitored in the pretreatment processes of two full-scale SWRO plants. Particulate Fouling potential was well controlled through the two stages of DMF with significant removal of SDI15 (>80%), MFI0.45 (94%) and microbial ATP (>95%). However, lower removal of Biological/organic Fouling potential (24–41%) was observed due to frequent chlorination (weekly) of the pretreatment, resulting in low Biological activity in the DMFs. Therefore, neutralizing chlorine before media filtration is advised, rather than after, as is the current practice in many full-scale SWRO plants. Comparing overall removal in the DAF-DMF pretreatment to that of the DMF pretreatment showed that DAF improved the removal of Biological/organic Fouling potential, in which the removal of BGP and biopolymers increased by 40% and 16%, respectively. Overall, monitoring ATP and BGP during the pretreatment processes, particularly in DMF, would be beneficial to enhance Biological degradation and lower bioFouling potential in SWRO feed water.
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seawater reverse osmosis desalination and harmful algal blooms
Desalination, 2015Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, Jan C Schippers, Assiyeh Alizadeh S Tabatabai, Donald M AndersonAbstract:Abstract This article reviews the occurrence of HABs in seawater, their effects on the operation of seawater reverse osmosis (SWRO) plants, the indicators for quantifying/predicting these effects, and the pretreatment strategies for mitigating operational issues during algal blooms. The potential issues in SWRO plants during HABs are particulate/organic Fouling of pretreatment systems and Biological Fouling of RO membranes, mainly due to accumulation of algal organic matter (AOM). The presence of HAB toxins in desalinated water is also a potential concern but only at very low concentrations. Monitoring algal cell density, AOM concentrations and membrane Fouling indices is a promising approach to assess the quality of SWRO feedwater and performance of the pretreatment system. When geological condition is favourable, subsurface intake can be a robust pretreatment for SWRO during HABs. Existing SWRO plants with open intake and are fitted with granular media filtration can improve performance in terms of capacity and product water quality, if preceded by dissolved air flotation or sedimentation. However, the application of advanced pretreatment using ultrafiltration membrane with in-line coagulation is often a better option as it is capable of maintaining stable operation and better RO feed water quality during algal bloom periods with significantly lower chemical consumption.
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improved method for measuring transparent exopolymer particles tep and their precursors in fresh and saline water
Water Research, 2015Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, Jan C Schippers, Yuli Ekowati, Helga N CalixponceAbstract:Transparent exopolymer particles (TEP) and their precursors produced by phyto-/bacterio-planktons in fresh and marine aquatic environments are increasingly considered as a major contributor to organic/particulate and Biological Fouling in micro-/ultra-filtration and reverse osmosis membrane (RO) systems. However, currently established methods which are based on Alcian blue (AB) staining and spectrophotometric techniques do not measure TEP-precursors and have the tendency to overestimate concentration in brackish/saline water samples due to interference of salinity on AB staining. Here we propose a new semi-quantitative method which allows measurement of both TEP and their colloidal precursors without the interference of salinity. TEP and their precursors are first retained on 10 kDa membrane, rinsed with ultra-pure water, and re-suspended in ultra-pure water by sonication and stained with AB, followed by exclusion of TEP-AB precipitates by filtration and absorbance measurement of residual AB. The concentration is then determined based on the reduction of AB absorbance due to reaction with acidic polysaccharides, blank correction and calibration with Xanthan gum standard. The extraction procedure allows concentration of TEP and their pre-cursors which makes it possible to analyse samples with a wide range of concentrations (down to <0.1 mg Xeq/L). This was demonstrated through application of the method for monitoring these compounds in algal cultures and a full-scale RO plant. The monitoring also revealed that concentrations of the colloidal precursors were substantially higher than the concentration of TEP themselves. In the RO plant, complete TEP removal was observed over the pre-treatment processes (coagulation-sedimentation-filtration and ultrafiltration) but the TEP precursors were not completely removed, emphasising the importance of measuring this colloidal component to better understand the role of TEP and acidic polysaccharides in RO membrane Fouling.
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the fate of transparent exopolymer particles tep in seawater uf ro system a pilot plant study in zeeland the netherlands
Desalination and Water Treatment, 2010Co-Authors: Loreen O Villacorte, Maria D Kennedy, Gary L Amy, Rinnert Schurer, Jan C SchippersAbstract:For many years, transparent exopolymer particles (TEP) were found abundant in various marine and freshwater environments, which are currently the main sources of raw water in desalination plants. Just recently, TEP have been identified as a potential foulant capable of causing organic and Biological Fouling in membrane systems. A pilot plant study was conducted to monitor the fate of TEP through the treatment process and to investigate their effects on the operational performance of a seawater UF-RO plant. Using spectrophotometric measurements, particulate (p-TEP > 0.4 mm) and colloidal (0.05 < c-TEP < 0.40 mm) species of TEP were measured at selected points in the plant. TEP monitoring in the raw water recorded a significant increase in both p-TEP and cTEP starting in early spring (March). This period was also marked by an increase of chlorophyll-a and total organic carbon (TOC) mainly attributed to an algal bloom occurrence in the water source. Total TEP from the raw water were partially removed by the micro-strainer (11–21%) and the UF system (*28%). Low Fouling rates in the UF were observed in January and February but severe Fouling were observed in late March and April, coinciding with the increase in TEP level. The severe Fouling was mitigated by applying in-line coagulation before the UF for which irreversible Fouling was significantly reduced. Deposition analyses indicated that significant amounts of p-TEP and c-TEP were deposited in the RO system. However, there was no significant decrease of RO normalized flux during the 4 months of operation in the plant. Long term monitoring is needed to better assess the adverse effects of TEP accumulation in the RO systems.