Drinking-water contamination by per-and poly uorinated alkyl substances (PFAS) is a global concer... more Drinking-water contamination by per-and poly uorinated alkyl substances (PFAS) is a global concern. Nano ltration is a promising PFAS removal technology due to its scalability and cost-effectiveness. However, nano ltration cannot typically reduce PFAS concentrations below current drinking-water recommendations. To enhance PFAS removal, we developed mixed-matrix-composite nano ltration (MMCNF) membranes-an active nano ltration layer on porous adsorptive support that synergetically combines ltration and adsorption. We synthesized MMCNF membranes comprising thin polyelectrolyte multilayer lms deposited on thick (~400 µm) polyethersulfone supports incorporating β-cyclodextrin microparticles. These membranes achieved near complete removal (>99.9%) of model PFAS (per uorooctanoic acid) for signi cantly longer ltration times compared to a control membrane without β-cyclodextrin, but otherwise identical. The spent MMCNF membrane was regenerated using ethanol, showing consistent performances in three ltration cycles. Per uorooctanoic acid was concentrated 38fold in the ethanol eluent. Further concentration by evaporation is straightforward and can enable eluent recycling and effective PFAS destruction.
The anaerobic treatment of industrial wastewater has attracted a significant amount of interest. ... more The anaerobic treatment of industrial wastewater has attracted a significant amount of interest. 11 However, excessive fouling complicates the treatment of anaerobic reactor effluent with 12 membranes, which limits the application of membranes as a tertiary treatment. Here, we use an 13 anaerobic sequencing batch reactor coupled to electrically conducting ultrafiltration and 14 nanofiltration membranes to treat high-strength industrial wastewater containing high 15 concentrations of benzyl alcohol, a commercial paint stripper. We demonstrate that an anaerobic 16 process can be used successfully to degrade this contaminant. We also show that the application 17 of negative electrical potential to the ultrafiltration membrane surface prevents membrane 18 fouling and allows for higher operational fluxes during the treatment of complex wastewater 19 streams. The application of positive potential to the membrane surface increases membrane 20 fouling, as well as hindering the cleaning and recovery of the nanofiltration membranes. Overall,
Bacterial biofilm formation on membrane surfaces remains a serious challenge in water treatment s... more Bacterial biofilm formation on membrane surfaces remains a serious challenge in water treatment systems. The impact of low voltages on microbial attachment to electrically conducting ultrafiltration membranes was investigated using a direct observation crossflow membrane system mounted on a fluorescence microscope. E.coli and microparticle deposition and detachment rates were measured as a function of the applied electrical potential to the membrane surface. Selecting bacteria and particles with low surface charge minimized electrostatic interactions between the bacteria and charged membrane surface. Application of an electrical potential had a significant impact on the detachment of live bacteria in comparison to dead bacteria and particles. Image analysis indicated that when a potential of 1.5 V was applied to the membrane/counter electrode pair, the percent of dead bacteria was 32±2.1% and 67±3.6%, when the membrane was used as a cathode or anode, respectively while at a potential of 1 V, 92±2.4% were alive. The application of low electrical potentials resulted in the production of low (µM) concentrations of hydrogen peroxide (HP) through the electroreduction of oxygen. The electrochemically-produced HP reduced microbial cell viability and increased cellular permeability. Exposure to low concentrations of electrochemically-produced HP on the membrane surface prevents bacterial attachment, thus ensuring biofilm-free conditions during membrane filtration operations.
Hexavalent chromium (Cr(VI)) contamination in drinking water resources remains a challenge in man... more Hexavalent chromium (Cr(VI)) contamination in drinking water resources remains a challenge in many parts of the United States, as well as in regions affected by industrial pollution. In this study, we demonstrated how electrically conducting carbon nanotube (CNT)polyvinyl alcohol (PVA) composite ultrafiltration (UF) membranes can be used to remove Cr(VI) from water through a combined process of electrostatic repulsion, electrochemical reduction, and precipitation. The impact of different operational (flux, contact time, applied electrical potential) and environmental (pH and salinity) conditions on Cr(VI) removal were evaluated. Due to the native electrical potential of the CNT/PVA UF membrane material, approximately 45% removal of 1 ppm Cr(VI) solution was detected under neutral pH conditions in deionized water. Increased Cr(VI) removal was observed with increasing membrane surface charge density, which was accomplished through the application of an external potential (3V, 5V and 7V, membrane as cathode) to the electrically conductive membrane surface. The solution ionic strength showed a significant impact on Cr(VI) removal. By increasing the ionic strength without applying external potential on the membrane, the electrostatic repulsive force between the charged membrane surface and the CrO 4 2ion was eliminated, and Cr(VI) removal dropped to zero. The highest removal (95%) was achieved when 7V was applied to the membrane/counter electrode with a 6 µm-thick membrane. Here, Cr(VI) was electrochemically reduced to Cr(III) on the membrane surface, followed by Cr(III) precipitation as chromium hydroxide Cr(OH) 3(s) , which occurred by Cr(III) reacting with hydroxide ions generated via water splitting on the CNT network. Precipitated Cr(OH) 3 was then removed by the UF membrane. In addition, CNT-PVA UF membranes were used to treat tap water spiked with Cr(VI); under these conditions, 99% Cr(VI) removal was observed when 7V were applied to the membrane/counter electrode. Furthermore, we demonstrate that other trace inorganic contaminants, such as uranium, were effectively removed as well.
ABSTRACT A commercial polypropylene spacer was coated via sonochemical nanosilver-deposition.•The... more ABSTRACT A commercial polypropylene spacer was coated via sonochemical nanosilver-deposition.•The modified spacer was efficient hindering biofouling in adjacent membranes.•HRSEM/CLSM analyses displayed significantly less attached bacteria on the membranes.•The silver coated spacers improved the permeate flux during the 10 days of the experiment.•Flow/mass transfer simulations show increased Ag concentration near the membrane.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This work aims to provide effective strategies and practical tools to control the diameter of fib... more This work aims to provide effective strategies and practical tools to control the diameter of fibers, a long-lasting challenge in the application of free surface melt electrospinning, mainly by hig...
• Antibacterial spacer was produced by grafting polymeric quaternary ammonium by ATRP. • A spacer... more • Antibacterial spacer was produced by grafting polymeric quaternary ammonium by ATRP. • A spacer coated via sonochemical nanosilver-deposition served as reference. • Both modified spacers efficiently hindered biofouling in adjacent membranes. • pQA grafted spacers display a localized antibacterial activity by direct contact. • nAg coated spacers have long-distance antibacterial activity-active species release.
In populated, water-scarce regions, seawater and wastewater are considered as potable water resou... more In populated, water-scarce regions, seawater and wastewater are considered as potable water resources that require extensive treatment before being suitable for consumption. The separation of water from salt, organic, and inorganic matter is most commonly done through membrane separation processes. Because of permeate flux and concentration polarization, membranes are prone to fouling, resulting in a decline in membrane performance and increased energy demands. As the physical and chemical properties of commercially available membranes (polymeric and ceramic) are relatively static and insensitive to changes in the environment, there is a need for stimuli-reactive membranes with controlled, tunable surface and transport properties to decrease fouling and control membrane properties such as hydrophilicity and permselectivity. In this review, we first describe the application of electricity-conducting and electricity-responsive membranes (ERMs) for fouling mitigation. We discuss their ability to reduce organic, inorganic, and biological fouling by several mechanisms, including control over the membrane’s surface morphology, electrostatic rejection, piezoelectric vibrations, electrochemical reactions, and local pH changes. Next, we examine the use of ERMs for permselectivity modification, which allows for the optimization of rejection and control over ion transport through the application of electrical potentials and the use of electrostatically charged membrane surfaces. In addition, electrochemical reactions coupled with membrane filtration are examined, including electro-oxidation and electro-Fenton reactions, demonstrating the capability of ERMs to electro-oxidize organic contaminates with high efficiency due to high surface area and reduced mass diffusion limitations. When applicable, ERM applications are compared with commercial membranes in terms of energy consumptions. We conclude with a brief discussion regarding the future directions of ERMs and provide examples of several applications such as pore size and selectivity control, electrowettability, and capacitive deionization. To provide the reader with the current state of knowledge, the review focuses on research published in the last 5 years.
bioRxiv (Cold Spring Harbor Laboratory), Jun 15, 2023
Mechanistic models can provide predictive insight into the design and optimization of engineered ... more Mechanistic models can provide predictive insight into the design and optimization of engineered biological systems, but the kinetic parameters in the models need to be frequently calibrated and uniquely identified. This limitation can be addressed by integrating mechanistic models with data-driven approaches, a strategy known as hybrid modeling. Herein, we developed a hybrid modeling strategy using bioelectrochemical systems as a platform system. The data-driven component of the model consisted of artificial neural networks (ANNs) that were trained by using mechanistically derived parameter values (e.g., the maximum specific growth rate µ max and the maximum substrate utilization rate k max for the fermentative, electroactive, and methanogenic populations, and the mediator yield for electroactive microbes Y M) as outputs to compute error signals. The hybrid model was built using 148 samples collected from 25 publications. After tenfold cross-validation, the model was tested with another 28 samples. Internal resistance was accurately predicted with a relative root-mean-square error (RMSE) of 3.9%. Microbial kinetic parameters were also calibrated using the data-driven component. They were fed into the mechanistic component to predict system performance. The R 2 between the predicted and observed organic removal and current production for systems fed with a simple substrate were 0.90 and 0.94, respectively, significantly higher than those obtained with a standalone data-driven model (0.51 and 0) and a standalone mechanistic model (0.07 and 0.15). The hybrid modeling strategy can potentially be applied to a variety of engineered biological systems for in silico system design and optimization.
Drinking-water contamination by per- and polyfluorinated alkyl substances (PFAS) is a global conc... more Drinking-water contamination by per- and polyfluorinated alkyl substances (PFAS) is a global concern. Nanofiltration is a promising PFAS removal technology due to its scalability and cost-effectiveness. However, nanofiltration cannot typically reduce PFAS concentrations below current drinking-water recommendations. To enhance PFAS removal, we developed mixed-matrix-composite nanofiltration (MMCNF) membranes - an active nanofiltration layer on porous adsorptive support that synergetically combines filtration and adsorption. We synthesized MMCNF membranes comprising thin polyelectrolyte multilayer films deposited on thick (~400 µm) polyethersulfone supports incorporating β-cyclodextrin microparticles. These membranes achieved near complete removal (>99.9%) of model PFAS (perfluorooctanoic acid) for significantly longer filtration times compared to a control membrane without β-cyclodextrin, but otherwise identical. The spent MMCNF membrane was regenerated using ethanol, showing cons...
In this work, poly (vinylidene fluoride) (PVDF) hierarchically porous membranes (HPMs) with isola... more In this work, poly (vinylidene fluoride) (PVDF) hierarchically porous membranes (HPMs) with isolated large pores and continuous narrow nano-pores have been fabricated from its blend with poly (methyl methacrylate) (PMMA) based on the combination of crystallization template with chemical or supercritical CO2 foaming. On the one hand, the decomposition of azodicarbonamide (ADC, chemical foaming agent) or the release of CO2 can produce isolated large pores. On the other hand, PMMA is expelled during the isothermal crystallization of PVDF in their miscible blend, yielding narrow nano-pores upon etching with a selective solvent. In the case of supercritical CO2, the attained PVDF HPMs fail to improve separation performance because of the compact wall of isolated-large-pore and consequent poor connectivity of hierarchical pores. In the case of ADC, the optimal HPM exhibits much higher flux (up to 20 times) without any loss of selectivity compared with the reference only with nano-pores. T...
Drinking-water contamination by per-and poly uorinated alkyl substances (PFAS) is a global concer... more Drinking-water contamination by per-and poly uorinated alkyl substances (PFAS) is a global concern. Nano ltration is a promising PFAS removal technology due to its scalability and cost-effectiveness. However, nano ltration cannot typically reduce PFAS concentrations below current drinking-water recommendations. To enhance PFAS removal, we developed mixed-matrix-composite nano ltration (MMCNF) membranes-an active nano ltration layer on porous adsorptive support that synergetically combines ltration and adsorption. We synthesized MMCNF membranes comprising thin polyelectrolyte multilayer lms deposited on thick (~400 µm) polyethersulfone supports incorporating β-cyclodextrin microparticles. These membranes achieved near complete removal (>99.9%) of model PFAS (per uorooctanoic acid) for signi cantly longer ltration times compared to a control membrane without β-cyclodextrin, but otherwise identical. The spent MMCNF membrane was regenerated using ethanol, showing consistent performances in three ltration cycles. Per uorooctanoic acid was concentrated 38fold in the ethanol eluent. Further concentration by evaporation is straightforward and can enable eluent recycling and effective PFAS destruction.
The anaerobic treatment of industrial wastewater has attracted a significant amount of interest. ... more The anaerobic treatment of industrial wastewater has attracted a significant amount of interest. 11 However, excessive fouling complicates the treatment of anaerobic reactor effluent with 12 membranes, which limits the application of membranes as a tertiary treatment. Here, we use an 13 anaerobic sequencing batch reactor coupled to electrically conducting ultrafiltration and 14 nanofiltration membranes to treat high-strength industrial wastewater containing high 15 concentrations of benzyl alcohol, a commercial paint stripper. We demonstrate that an anaerobic 16 process can be used successfully to degrade this contaminant. We also show that the application 17 of negative electrical potential to the ultrafiltration membrane surface prevents membrane 18 fouling and allows for higher operational fluxes during the treatment of complex wastewater 19 streams. The application of positive potential to the membrane surface increases membrane 20 fouling, as well as hindering the cleaning and recovery of the nanofiltration membranes. Overall,
Bacterial biofilm formation on membrane surfaces remains a serious challenge in water treatment s... more Bacterial biofilm formation on membrane surfaces remains a serious challenge in water treatment systems. The impact of low voltages on microbial attachment to electrically conducting ultrafiltration membranes was investigated using a direct observation crossflow membrane system mounted on a fluorescence microscope. E.coli and microparticle deposition and detachment rates were measured as a function of the applied electrical potential to the membrane surface. Selecting bacteria and particles with low surface charge minimized electrostatic interactions between the bacteria and charged membrane surface. Application of an electrical potential had a significant impact on the detachment of live bacteria in comparison to dead bacteria and particles. Image analysis indicated that when a potential of 1.5 V was applied to the membrane/counter electrode pair, the percent of dead bacteria was 32±2.1% and 67±3.6%, when the membrane was used as a cathode or anode, respectively while at a potential of 1 V, 92±2.4% were alive. The application of low electrical potentials resulted in the production of low (µM) concentrations of hydrogen peroxide (HP) through the electroreduction of oxygen. The electrochemically-produced HP reduced microbial cell viability and increased cellular permeability. Exposure to low concentrations of electrochemically-produced HP on the membrane surface prevents bacterial attachment, thus ensuring biofilm-free conditions during membrane filtration operations.
Hexavalent chromium (Cr(VI)) contamination in drinking water resources remains a challenge in man... more Hexavalent chromium (Cr(VI)) contamination in drinking water resources remains a challenge in many parts of the United States, as well as in regions affected by industrial pollution. In this study, we demonstrated how electrically conducting carbon nanotube (CNT)polyvinyl alcohol (PVA) composite ultrafiltration (UF) membranes can be used to remove Cr(VI) from water through a combined process of electrostatic repulsion, electrochemical reduction, and precipitation. The impact of different operational (flux, contact time, applied electrical potential) and environmental (pH and salinity) conditions on Cr(VI) removal were evaluated. Due to the native electrical potential of the CNT/PVA UF membrane material, approximately 45% removal of 1 ppm Cr(VI) solution was detected under neutral pH conditions in deionized water. Increased Cr(VI) removal was observed with increasing membrane surface charge density, which was accomplished through the application of an external potential (3V, 5V and 7V, membrane as cathode) to the electrically conductive membrane surface. The solution ionic strength showed a significant impact on Cr(VI) removal. By increasing the ionic strength without applying external potential on the membrane, the electrostatic repulsive force between the charged membrane surface and the CrO 4 2ion was eliminated, and Cr(VI) removal dropped to zero. The highest removal (95%) was achieved when 7V was applied to the membrane/counter electrode with a 6 µm-thick membrane. Here, Cr(VI) was electrochemically reduced to Cr(III) on the membrane surface, followed by Cr(III) precipitation as chromium hydroxide Cr(OH) 3(s) , which occurred by Cr(III) reacting with hydroxide ions generated via water splitting on the CNT network. Precipitated Cr(OH) 3 was then removed by the UF membrane. In addition, CNT-PVA UF membranes were used to treat tap water spiked with Cr(VI); under these conditions, 99% Cr(VI) removal was observed when 7V were applied to the membrane/counter electrode. Furthermore, we demonstrate that other trace inorganic contaminants, such as uranium, were effectively removed as well.
ABSTRACT A commercial polypropylene spacer was coated via sonochemical nanosilver-deposition.•The... more ABSTRACT A commercial polypropylene spacer was coated via sonochemical nanosilver-deposition.•The modified spacer was efficient hindering biofouling in adjacent membranes.•HRSEM/CLSM analyses displayed significantly less attached bacteria on the membranes.•The silver coated spacers improved the permeate flux during the 10 days of the experiment.•Flow/mass transfer simulations show increased Ag concentration near the membrane.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
This work aims to provide effective strategies and practical tools to control the diameter of fib... more This work aims to provide effective strategies and practical tools to control the diameter of fibers, a long-lasting challenge in the application of free surface melt electrospinning, mainly by hig...
• Antibacterial spacer was produced by grafting polymeric quaternary ammonium by ATRP. • A spacer... more • Antibacterial spacer was produced by grafting polymeric quaternary ammonium by ATRP. • A spacer coated via sonochemical nanosilver-deposition served as reference. • Both modified spacers efficiently hindered biofouling in adjacent membranes. • pQA grafted spacers display a localized antibacterial activity by direct contact. • nAg coated spacers have long-distance antibacterial activity-active species release.
In populated, water-scarce regions, seawater and wastewater are considered as potable water resou... more In populated, water-scarce regions, seawater and wastewater are considered as potable water resources that require extensive treatment before being suitable for consumption. The separation of water from salt, organic, and inorganic matter is most commonly done through membrane separation processes. Because of permeate flux and concentration polarization, membranes are prone to fouling, resulting in a decline in membrane performance and increased energy demands. As the physical and chemical properties of commercially available membranes (polymeric and ceramic) are relatively static and insensitive to changes in the environment, there is a need for stimuli-reactive membranes with controlled, tunable surface and transport properties to decrease fouling and control membrane properties such as hydrophilicity and permselectivity. In this review, we first describe the application of electricity-conducting and electricity-responsive membranes (ERMs) for fouling mitigation. We discuss their ability to reduce organic, inorganic, and biological fouling by several mechanisms, including control over the membrane’s surface morphology, electrostatic rejection, piezoelectric vibrations, electrochemical reactions, and local pH changes. Next, we examine the use of ERMs for permselectivity modification, which allows for the optimization of rejection and control over ion transport through the application of electrical potentials and the use of electrostatically charged membrane surfaces. In addition, electrochemical reactions coupled with membrane filtration are examined, including electro-oxidation and electro-Fenton reactions, demonstrating the capability of ERMs to electro-oxidize organic contaminates with high efficiency due to high surface area and reduced mass diffusion limitations. When applicable, ERM applications are compared with commercial membranes in terms of energy consumptions. We conclude with a brief discussion regarding the future directions of ERMs and provide examples of several applications such as pore size and selectivity control, electrowettability, and capacitive deionization. To provide the reader with the current state of knowledge, the review focuses on research published in the last 5 years.
bioRxiv (Cold Spring Harbor Laboratory), Jun 15, 2023
Mechanistic models can provide predictive insight into the design and optimization of engineered ... more Mechanistic models can provide predictive insight into the design and optimization of engineered biological systems, but the kinetic parameters in the models need to be frequently calibrated and uniquely identified. This limitation can be addressed by integrating mechanistic models with data-driven approaches, a strategy known as hybrid modeling. Herein, we developed a hybrid modeling strategy using bioelectrochemical systems as a platform system. The data-driven component of the model consisted of artificial neural networks (ANNs) that were trained by using mechanistically derived parameter values (e.g., the maximum specific growth rate µ max and the maximum substrate utilization rate k max for the fermentative, electroactive, and methanogenic populations, and the mediator yield for electroactive microbes Y M) as outputs to compute error signals. The hybrid model was built using 148 samples collected from 25 publications. After tenfold cross-validation, the model was tested with another 28 samples. Internal resistance was accurately predicted with a relative root-mean-square error (RMSE) of 3.9%. Microbial kinetic parameters were also calibrated using the data-driven component. They were fed into the mechanistic component to predict system performance. The R 2 between the predicted and observed organic removal and current production for systems fed with a simple substrate were 0.90 and 0.94, respectively, significantly higher than those obtained with a standalone data-driven model (0.51 and 0) and a standalone mechanistic model (0.07 and 0.15). The hybrid modeling strategy can potentially be applied to a variety of engineered biological systems for in silico system design and optimization.
Drinking-water contamination by per- and polyfluorinated alkyl substances (PFAS) is a global conc... more Drinking-water contamination by per- and polyfluorinated alkyl substances (PFAS) is a global concern. Nanofiltration is a promising PFAS removal technology due to its scalability and cost-effectiveness. However, nanofiltration cannot typically reduce PFAS concentrations below current drinking-water recommendations. To enhance PFAS removal, we developed mixed-matrix-composite nanofiltration (MMCNF) membranes - an active nanofiltration layer on porous adsorptive support that synergetically combines filtration and adsorption. We synthesized MMCNF membranes comprising thin polyelectrolyte multilayer films deposited on thick (~400 µm) polyethersulfone supports incorporating β-cyclodextrin microparticles. These membranes achieved near complete removal (>99.9%) of model PFAS (perfluorooctanoic acid) for significantly longer filtration times compared to a control membrane without β-cyclodextrin, but otherwise identical. The spent MMCNF membrane was regenerated using ethanol, showing cons...
In this work, poly (vinylidene fluoride) (PVDF) hierarchically porous membranes (HPMs) with isola... more In this work, poly (vinylidene fluoride) (PVDF) hierarchically porous membranes (HPMs) with isolated large pores and continuous narrow nano-pores have been fabricated from its blend with poly (methyl methacrylate) (PMMA) based on the combination of crystallization template with chemical or supercritical CO2 foaming. On the one hand, the decomposition of azodicarbonamide (ADC, chemical foaming agent) or the release of CO2 can produce isolated large pores. On the other hand, PMMA is expelled during the isothermal crystallization of PVDF in their miscible blend, yielding narrow nano-pores upon etching with a selective solvent. In the case of supercritical CO2, the attained PVDF HPMs fail to improve separation performance because of the compact wall of isolated-large-pore and consequent poor connectivity of hierarchical pores. In the case of ADC, the optimal HPM exhibits much higher flux (up to 20 times) without any loss of selectivity compared with the reference only with nano-pores. T...
Uploads
Papers by Avner Ronen