The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
A G Fane - One of the best experts on this subject based on the ideXlab platform.
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behavior of oil droplets at the membrane surface during crossFlow microfiltration of oil water emulsions
Journal of Membrane Science, 2016Co-Authors: Emily N Tummons, Volodymyr V Tarabara, Jia Wei Chew, A G FaneAbstract:Abstract A fundamental study of microfiltration membrane fouling by emulsified oil was conducted using a combination of real-time visualization, force balance on a droplet, and Permeate flux analysis. The model 0.1% v/v hexadecane-in-water emulsions contained sodium dodecyl sulfate (0.1 mM, 0.4 mM, or 0.8 mM) to regulate interfacial tension. Direct Observation Through the Membrane tests with Anopore ( d pore =0.2 µm) and track-etch ( d pore =5 µm) membranes revealed three characteristic stages of membrane fouling: (1) droplet attachment and clustering, (2) droplet deformation, and (3) droplet coalescence. In qualitative agreement with visualization results, the force balance predicted that droplets ≲ 36–40 µm would remain pinned at d pore =5 µm pores while larger droplets would be swept off the surface by the crossFlow drag. In a separate set of constant pressure crossFlow filtration tests with track-etch membranes, the average oil rejection was ≥98% while the Permeate flux decreased to a pseudo-steady-state ~10% of the initial value. The results indicate that membrane fouling by emulsified oil is controlled by droplet coalescence and crossFlow shear: the transport of oil to the membrane surface by the Permeate Flow is balanced by the shear-induced removal of the droplets that coalesce to exceed a critical size.
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performance enhancement and scaling control with gas bubbling in direct contact membrane distillation
Desalination, 2013Co-Authors: Guizi Chen, Xing Yang, Rong Wang, A G FaneAbstract:This study incorporates gas bubbling into direct contact membrane distillation (DCMD) and examines its effect on the MD performance especially at elevated salt concentrations in the feed steam. Process optimization in the bubbling assisted DCMD process was carried out which involved varying operating conditions and module configurations. Also, observations were performed for the scaling status on the membrane surface with operating time in different modules to further understand the role of gas bubbling in affecting the behavior of crystal deposition when the salt concentration has reached super-saturation. Due to intensified local mixing and physical Flow disturbance in the liquid boundary layer on the feed side, a higher flux enhancement could be achieved in a bubbling system with either a higher feed operating temperature, lower feed and Permeate Flow velocities, inclined module orientation, shorter fiber length or lower packing density. It was also found that gas bubbling not only enhanced the permeation flux by average 26% when concentrating feed solution from 18% salt concentration to saturation, but also delayed the occurrence of major flux decline due to crystal deposition when compared to the module with spacers. These results were confirmed by membrane surface autopsy at different operating stages using SEM.
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the use of constant temperature anemometry for Permeate Flow distribution measurement in a submerged hollow fibre system
Journal of Membrane Science, 2009Co-Authors: Filicia Wicaksana, A G Fane, Adrian Wingkeung LawAbstract:This study investigates the application of the Constant Temperature Anemometry (CTA) technique to determine the Flow distribution among hollow fibre bundles in a submerged membrane system. Membrane filtration was performed at constant Permeate flux with five submerged hollow fibre membrane mini-bundles, representing regions of a submerged module, operating in parallel through a common suction pump. Five CTA sensors were located in a matrix above the outlets of the bundles so that the individual contributions of each bundle region to the net Permeate Flow could be monitored. This allowed measurement of the system response to simulated localised fouling or blocking, aeration failure and restoration of aeration. The CTA sensors were able to monitor the Permeate Flow distribution among the fibre bundles when mal-distribution of Flow occurred in the system. Satisfactory performance of the CTA sensors was verified by comparing the amount of cake deposited on the membrane surface of the fibre bundles with the local flux behaviour. The results demonstrated the potential of using the CTA approach to characterise the cross-sectional fouling or blocking variation in a submerged hollow fibre membrane system. It is evident that this approach could be applied in other module configurations. Technical challenges to this CTA application are discussed.
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analysis of constant Permeate Flow filtration using dead end hollow fiber membranes
Journal of Membrane Science, 2006Co-Authors: Sheng Chang, A G Fane, T D WaiteAbstract:Abstract Dead-end filtration of colloids using hollow fibers has been analysed theoretically and experimentally. A mathematical model for constant flux filtration using dead-end hollow fiber membranes has been developed by combining the Hagen–Poiseuille equation, the (standard) filtration equation, and cake filtration theory of Petsev et al. [D.N. Petsev, V.M. Starov, I.B. Ivanov, Concentrated dispersions of charged colloidal particles: sedimentation, ultrafiltration and diffusion, Colloid Surf. A: Physicochem. Eng. Aspects, 81 (1993) 65–81.] to describe the time dependence of the filtration behavior of hollow fiber membranes experiencing particle deposition on their surface. Instead of using traditional constitutive equations, the resistance of the cake layer formed by the deposited colloids has been directly correlated to the cake structure. This structure is determined by application of a force balance on a particle in the cake layer combined with the assumption that an electrostatically stable cake layer of mono-sized particles would be ordered in a regular packing geometry of minimum energy. The developed model has been used to identify the relationship between the filtration behavior of the hollow fiber membrane and the particle properties, fiber size, and imposed average flux. Filtration experiments using polystyrene latex particles of relatively narrow size distribution with a single dead-end hollow fiber membrane demonstrate good consistency between experimental results and model prediction. The developed model has been used to simulate the distribution of the cake resistance, transmembrane pressure, and flux along the hollow fiber membrane and used to assess the effect of fiber size, particle size, zeta potential, and the average imposed flux on the suction pressure-time profiles, flux, and cake resistance distributions. These results provide new insights into the filtration behavior of the hollow fiber membrane under constant flux conditions.
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the effects of intermittent Permeate Flow and crossFlow on membrane coalescence of oil in water emulsions
Desalination, 2002Co-Authors: Amauri C Hong, A G Fane, Robert P BurfordAbstract:Abstract Membrane coalescence is a chemical-free technique for breaking stable oil-in-water emulsions. In this work the effect of oil droplet residence time within the membrane porous matrix was investigated and a novel process is proposed based on intermittent Permeate Flow (Flow or no Flow) at 0.01 Hz. Polytetrafluoroethylene membranes with 0.45 and 1.20 μm nominal average pore size were used to coalesce emulsions with an average 1.5 μm droplet diameter. Experiments were carried out in a crossFlow filtration cell and crossFlow velocities were varied from 0.07 to 0.28 ms−1. Fluxes were found to increase with crossFlow although oil rejection was zero, implying no concentration polarization. Results also demonstrated an improvement in coalescence performance during intermittent operation at low crossFlow velocities. Under some conditions intermittent Permeate Flow operation produced higher Permeate fluxes than without intermittent operation and is a potential novel process for membrane coalescence.
Yoram Cohen - One of the best experts on this subject based on the ideXlab platform.
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effect of thermodynamic restriction on energy cost optimization of ro membrane water desalination
Industrial & Engineering Chemistry Research, 2009Co-Authors: Panagiotis D Christofides, Yoram CohenAbstract:Advances in highly permeable reverse osmosis (RO) membranes have enabled desalting operations, in which it is practically feasible for the applied pressure to approach the osmotic pressure of the exit brine stream. However, energy cost remains a major contributor to the total cost of water produced by RO membrane desalination. Reduction of the overall cost of water production represents a major challenge and, in the present work, various elements of water production cost are evaluated from the viewpoint of optimization, with respect to various costs (energy, membrane area and permeability, brine management, and pressure drop), as well as the important thermodynamic cross-Flow constraint, utilization of energy recovery devices, and operational feed and Permeate Flow rate constraints. More specifically, in the present study, an approach to the optimization of product water recovery at pressures that approach the osmotic pressure of the exit brine stream is presented via several simple RO process models that...
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energy consumption optimization of reverse osmosis membrane water desalination subject to feed salinity fluctuation
Industrial & Engineering Chemistry Research, 2009Co-Authors: Aihua Zhu, Panagiotis D Christofides, Yoram CohenAbstract:We study the energy consumption optimization of a reverse osmosis water desalination process producing a constant Permeate Flow in the presence of feed concentration fluctuation. We propose a time-varying optimal operation strategy that can significantly reduce the specific energy consumption compared to time-invariant process operation. We present both computational and experimental results that demonstrate the effectiveness of the proposed optimal operation policy.
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energy consumption optimization of ro membrane desalination subject to feed salinity fluctuation the present work was supported in part by the international desalination association channabasappa memorial scholarship to aihua zhu california departmen
IFAC Proceedings Volumes, 2009Co-Authors: Aihua Zhu, Panagiotis D Christofides, Yoram CohenAbstract:Abstract Abstract We study the energy consumption optimization of a reverse osmosis water desalination process producing a constant Permeate Flow in the presence of feed concentration fluctuation. We propose a time-varying optimal operation strategy that can significantly reduce the specific energy consumption compared to time-invariant process operation.
M Sancho - One of the best experts on this subject based on the ideXlab platform.
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aquapot study of the causes in reduction of Permeate Flow in spiral wound uf membrane simulation of a non rigorous cleaning protocol in a drinkable water treatment facility
Desalination, 2008Co-Authors: J M Arnal, B Garciafayos, G Verdu, J Lora, M SanchoAbstract:In the last two years, international AQUAPOT project has carried out the installation of three drinking water treatment plants based on ultrafiltration (UF), in rural areas of the Andean region of Ecuador without access to drinking water. In addition, the project has carried out an applied parallel investigation in the Naquera Research Centre (CIN) in Valencia that has by objective the anticipation to the problems that can arise in the operation of the drinking water facilities already installed, as a consequence of a non-rigorous cleaning protocol. For the investigation, analogous drinking water treatment plants to the ones installed in Ecuador have been used, working continuously in long-term operation assay and using as feed superficial water with a high microbiological contamination. Cleaning protocol was applied every 7 days using a cleaning solution an basic and acid agent followed by a disinfectant reagent. Results after 6 months of test, showed a progressive decrease of the Permeate Flow and presence of microbiological contamination. This work exposes main results and conclusions from real assays, and recommendations to achieve a correct operation of the UF plant.
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aquapot study of several cleaning solutions to recover Permeate Flow in a humanitarian drinking water treatment facility based on spiral wound uf membrane preliminary test i
Desalination, 2008Co-Authors: J M Arnal, B Garciafayos, G Verdu, J Lora, M SanchoAbstract:Abstract Access to safe drinkable water is a basic human right and an international goal. Since 1996, AQUAPOT international project, has researched and developed low cost, easy to use and effective water treatment technologies able to be used in developing countries. Recently, the project has carried out the design of three potabilization units based on membrane technology and its installation in rural areas of Ecuador with no access to safe water. Field experience has shown that maintenance and cleaning of spiral wound ultrafiltration membranes is not done properly what can reduce the membrane’s life due to biofilm growth. In a medium term, this growth would affect the quality and the volume of the pure water produced by the drinkable water treatment facility. An applied research has been initiated to study several cleaning solutions that allow to recover an optimum Permeate Flow. For the preliminary test, samples from UF membrane were used. Methodology includes static assays in which membrane’s samples were immersed in a cleaning solution for over 12 or 24h at a temperature of 25 to 40°C. The study has allowed to select the most effective membrane’s cleaning solutions and the optimum conditions for its application. In addition, the study has allowed to verify the efficiency of the cleaning reagent in a drinkable water treatment plant.
J M Arnal - One of the best experts on this subject based on the ideXlab platform.
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aquapot study of the causes in reduction of Permeate Flow in spiral wound uf membrane simulation of a non rigorous cleaning protocol in a drinkable water treatment facility
Desalination, 2008Co-Authors: J M Arnal, B Garciafayos, G Verdu, J Lora, M SanchoAbstract:In the last two years, international AQUAPOT project has carried out the installation of three drinking water treatment plants based on ultrafiltration (UF), in rural areas of the Andean region of Ecuador without access to drinking water. In addition, the project has carried out an applied parallel investigation in the Naquera Research Centre (CIN) in Valencia that has by objective the anticipation to the problems that can arise in the operation of the drinking water facilities already installed, as a consequence of a non-rigorous cleaning protocol. For the investigation, analogous drinking water treatment plants to the ones installed in Ecuador have been used, working continuously in long-term operation assay and using as feed superficial water with a high microbiological contamination. Cleaning protocol was applied every 7 days using a cleaning solution an basic and acid agent followed by a disinfectant reagent. Results after 6 months of test, showed a progressive decrease of the Permeate Flow and presence of microbiological contamination. This work exposes main results and conclusions from real assays, and recommendations to achieve a correct operation of the UF plant.
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aquapot study of several cleaning solutions to recover Permeate Flow in a humanitarian drinking water treatment facility based on spiral wound uf membrane preliminary test i
Desalination, 2008Co-Authors: J M Arnal, B Garciafayos, G Verdu, J Lora, M SanchoAbstract:Abstract Access to safe drinkable water is a basic human right and an international goal. Since 1996, AQUAPOT international project, has researched and developed low cost, easy to use and effective water treatment technologies able to be used in developing countries. Recently, the project has carried out the design of three potabilization units based on membrane technology and its installation in rural areas of Ecuador with no access to safe water. Field experience has shown that maintenance and cleaning of spiral wound ultrafiltration membranes is not done properly what can reduce the membrane’s life due to biofilm growth. In a medium term, this growth would affect the quality and the volume of the pure water produced by the drinkable water treatment facility. An applied research has been initiated to study several cleaning solutions that allow to recover an optimum Permeate Flow. For the preliminary test, samples from UF membrane were used. Methodology includes static assays in which membrane’s samples were immersed in a cleaning solution for over 12 or 24h at a temperature of 25 to 40°C. The study has allowed to select the most effective membrane’s cleaning solutions and the optimum conditions for its application. In addition, the study has allowed to verify the efficiency of the cleaning reagent in a drinkable water treatment plant.
Panagiotis D Christofides - One of the best experts on this subject based on the ideXlab platform.
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effect of thermodynamic restriction on energy cost optimization of ro membrane water desalination
Industrial & Engineering Chemistry Research, 2009Co-Authors: Panagiotis D Christofides, Yoram CohenAbstract:Advances in highly permeable reverse osmosis (RO) membranes have enabled desalting operations, in which it is practically feasible for the applied pressure to approach the osmotic pressure of the exit brine stream. However, energy cost remains a major contributor to the total cost of water produced by RO membrane desalination. Reduction of the overall cost of water production represents a major challenge and, in the present work, various elements of water production cost are evaluated from the viewpoint of optimization, with respect to various costs (energy, membrane area and permeability, brine management, and pressure drop), as well as the important thermodynamic cross-Flow constraint, utilization of energy recovery devices, and operational feed and Permeate Flow rate constraints. More specifically, in the present study, an approach to the optimization of product water recovery at pressures that approach the osmotic pressure of the exit brine stream is presented via several simple RO process models that...
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energy consumption optimization of reverse osmosis membrane water desalination subject to feed salinity fluctuation
Industrial & Engineering Chemistry Research, 2009Co-Authors: Aihua Zhu, Panagiotis D Christofides, Yoram CohenAbstract:We study the energy consumption optimization of a reverse osmosis water desalination process producing a constant Permeate Flow in the presence of feed concentration fluctuation. We propose a time-varying optimal operation strategy that can significantly reduce the specific energy consumption compared to time-invariant process operation. We present both computational and experimental results that demonstrate the effectiveness of the proposed optimal operation policy.
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energy consumption optimization of ro membrane desalination subject to feed salinity fluctuation the present work was supported in part by the international desalination association channabasappa memorial scholarship to aihua zhu california departmen
IFAC Proceedings Volumes, 2009Co-Authors: Aihua Zhu, Panagiotis D Christofides, Yoram CohenAbstract:Abstract Abstract We study the energy consumption optimization of a reverse osmosis water desalination process producing a constant Permeate Flow in the presence of feed concentration fluctuation. We propose a time-varying optimal operation strategy that can significantly reduce the specific energy consumption compared to time-invariant process operation.