401 results on '"Biofouling"'
Search Results
2. Biofouling evolution driven by autoinducer-2 quorum sensing in reverse osmosis (RO) for water reclamation
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Xu, Huijuan, Lee, Seonki, Chia, Rui Yun, and Chong, Tzyy Haur
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- 2025
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3. Vibrio neptunius-ULV11 cell-free supernatant as a promising antifouling approach in reverse osmosis systems
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Vera-Villalobos, Hernán, Cruz-Balladares, Victoria, González-Gutiérrez, Álvaro, Avalos, Vladimir, Riquelme, Carlos, and Silva-Aciares, Fernando
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- 2024
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4. Priority bacteria causing biofouling of reverse osmosis membranes: Potential disinfection-resistant bacteria and control strategies
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Gao, Yujia, Wang, Haobin, Xu, Yuqing, Wang, Ruining, Liu, Han, Qiu, Yu, Hong, Yu, Hu, Hongying, and Wu, Yinhu
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- 2024
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5. Improved cleaning performance of membrane modules using feed spacers modified with cold-plasma treatment and polydopamine and silver-nanoparticle coatings.
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Huisman, Kees Theo, Abdellah, Mohamed H., Alvarez Sosa, Damaris S., Fernandes Simoes, Filipa R., Blankert, Bastiaan, Vrouwenvelder, Johannes S., and Szekely, Gyorgy
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DOPAMINE , *SURFACE coatings , *MEMBRANE separation , *WATER shortages , *SILVER nanoparticles , *FOULING - Abstract
Membrane modules for seawater desalination are becoming increasingly important for obtaining clean water with the rising global water scarcity. The productivity of membrane modules is compromised by biofouling on the membrane and feed spacer. Biofouling development can be mitigated by modification of the spacer or membrane surface. The purpose of the present study is to evaluate the impact of surface-modified feed spacers on the cleaning performance of spiral-wound membrane filtration systems. After cold-plasma treatment, the feed spacers were modified with various combinations of polydopamine (PDA) and silver nanoparticles (AgNP). To compare the cleaning performance of the modified and unmodified spacers, membrane fouling simulators containing nanofiltration membranes and feed spacers were tested under industrially representative conditions: two full cycles involving biofilm development followed by cleaning-in-place (CIP). The modified spacers significantly improved the CIP efficiency when compared with that of the unmodified feed spacer. The highest CIP efficiency was obtained for the PDA–AgNP-coated spacers, which removed >90 % of the biomass. The PDA layers remained undetached during the CIP process, and the amounts of AgNP decreased without affecting the CIP effectiveness during consecutive operational cycles. The results demonstrate that CIP should be included in biofouling tests to evaluate the full potential of surface modifications and suggest that hydrophilic and biocidal spacer surface coatings can significantly improve the CIP effectiveness, thereby considerably reducing the CIP frequency and operational costs. [Display omitted] • Cold-plasma treatment enables hydrophilic modification of hydrophobic feed spacers. • Hydrophilic and biocidal coatings were grafted onto cold-plasma-treated feed spacers. • Coatings were tested for biofouling control under industrial operating conditions. • Hydrophilic and biocidal coatings improved the cleaning-in-place effectiveness. • Improved cleaning effectiveness was maintained over several operational cycles. [ABSTRACT FROM AUTHOR]
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- 2024
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6. Oil-infused feed spacers for biofouling inhibition.
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Boyko, A., Epstein, J.A., and Ramon, G.Z.
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FOULING , *ESCHERICHIA coli , *BACTERIAL adhesion , *BACTERIAL cell surfaces , *FOULING organisms , *MICROBIAL growth , *REVERSE osmosis - Abstract
A novel approach is investigated for preventing biofouling of spacer filaments, which are an essential part of spiral-wound modules used in membrane-based desalination. Biofouling, caused by the growth and multiplication of microorganisms on the membrane surface, can significantly impact the efficiency and cost-effectiveness of the desalination process. Herein, a method is proposed for fabricating modified feed spacers based on oil-infused slippery substrates made of polydimethylsiloxane (PDMS). These feed spacers, when infused with silicone oil, create a stable, extremely slippery interface that exhibits exceptionally low bacterial adhesion and prevents biofilm formation, especially under flow conditions. By examining the effect of the silicone oil's viscosity, we determined the optimal ratio of the curing agent for fabricating the oil-infused feed spacer. Results showed a substantial reduction of bacterial adhesion to the surface for all tested oil viscosities, particularly under dynamic conditions. Furthermore, even where bacterial adhesion occurred, primarily on samples infused with lower-viscosity oil, it could be easily removed by simple rinsing. Overall, the oil-infused feed spacer demonstrated exceptional biofilm inhibition, providing preliminary indication of the potential offered by this promising approach. • Oil-impregnated PDMS spacers used to test biofouling prevention • PDMS stiffness and oil viscosity affect oil uptake and retention. • Reduced and easily removable biofilm growth on oily substrate • E. coli biofilm mitigation demonstrated on oil-infused PDMS spacer • Lower viscosity oil and lower stiffness PDMS demonstrate best performance. [ABSTRACT FROM AUTHOR]
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- 2024
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7. Acidification and decarbonization in seawater: Potential pretreatment steps for biofouling control in SWRO membranes.
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Harlev, Noam, Bogler, Anne, Lahav, Ori, and Herzberg, Moshe
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OCEAN acidification , *CELL membrane formation , *REVERSE osmosis , *PARTICULATE matter , *FOULING , *MEMBRANE permeability (Technology) - Abstract
Biofouling of seawater reverse osmosis (SWRO) membranes is a major problem that SWRO freshwater production facilities face worldwide. A three-step pretreatment scheme, initially designed to assist the SWRO process in boron rejection, was examined as a potential membrane biofouling inhibitor. The conventional pretreatment procedure in this study includes acidification, CO 2 stripping and pH elevation, and its effect on planktonic cell mortality and biofilm formation on the membrane was analyzed. An in-situ electrolytic production of free chlorine in seawater, during the low pH phase, was suggested as an additional pretreatment step, with the goal of serving as an aggressive disinfection course. In addition, 48-hour enhanced biofouling experiments using an RO membrane cell assembly were conducted in order to observe the flux decline pattern as affected by the various treatments. The conventional pretreatment scheme was found to have a moderate effect on membrane biofouling, increasing the membrane permeability by 25% relative to an untreated experimental run. Moreover, the conventional pretreatment did not significantly promote cell mortality; however, it caused an increase in extracellular polysaccharide production during biofilm formation. The additional chlorination step increased the biofouling phenomenon, causing the production of particulate matter, likely due to cell wall oxidation. • The acidification, CO 2 stripping and pH elevation pretreatments designed for Boron removal reduces biofouling phenomenon. • Supplement of chlorine during the low pH phase of the pretreatment scheme increased biofouling. • Extracellular polysaccharide production was elevated for the pretreatment, though, cell attachment reduced. [ABSTRACT FROM AUTHOR]
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- 2019
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8. Assessing pretreatment and seawater reverse osmosis performance using an ATP-based bacterial growth potential method.
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Abushaban, Almotasembellah, Salinas-Rodriguez, Sergio G., Dhakal, Nirajan, Schippers, Jan C., and Kennedy, Maria D.
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REVERSE osmosis , *BACTERIAL growth , *SEAWATER , *BRACKISH waters , *DISSOLVED organic matter , *CHEMICAL cleaning - Abstract
Various bacterial growth potential (BGP) methods have been developed recently to monitor biofouling in seawater reverse osmosis (SWRO) systems such as assimilable organic carbon and bacterial regrowth potential. However, the relationship between these methods and biofouling in SWRO desalination plants has not yet been demonstrated. In this research, an attempt is made to investigate if a correlation exists between BGP of SWRO feed water and the chemical cleaning frequency in SWRO plants using an ATP-based BGP method employing an indigenous microbial consortium. Using ATP-based BGP method at 5 different seawater locations showed low variations of bacterial yield. The BGP method was applied to assess the pretreatment performance of three full-scale SWRO plants with different pretreatment processes. Dual media filtration (DMF) showed the highest BGP removal (>50%) in two SWRO plants. Removal of BGP and hydrophilic organic carbon in dissolved air floatation combined with ultrafiltration was similar to the removal achieved with DMF in combination with inline coagulation. For the three SWRO plants investigated, a higher BGP in SWRO feed water corresponded to a higher chemical cleaning frequency. However, more data is required to confirm if a real correlation exists between BGP and biofouling in SWRO plants. • BGP in seawater was measured using ATP with indigenous microbial consortium. • Bacterial growth in seawater correlated to the added glucose concentration. • BGP was monitored through the pretreatment of three full-scale SWRO plants. • Higher BGP in SWRO feed corresponded to a higher CIP frequency in three SWRO plants. [ABSTRACT FROM AUTHOR]
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- 2019
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9. ATP measurement in seawater reverse osmosis systems: Eliminating seawater matrix effects using a filtration-based method.
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Abushaban, Almotasembellah, Salinas-Rodriguez, Sergio G., Mangal, Muhammad Nasir, Mondal, Subhanjan, Goueli, Said A., Knezev, Aleksandra, Vrouwenvelder, Johannes S., Schippers, Jan C., and Kennedy, Maria D.
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ADENOSINE triphosphate , *REVERSE osmosis , *SALINE water conversion , *WATER quality , *FILTERS & filtration - Abstract
Abstract A direct method for measuring adenosine-triphosphate (ATP) in seawater was developed recently, in which commercial reagents are added directly to seawater. However, calibration is required if seawater quality changes (such as changes in salinity, pH, Mg2+, Fe3+) as the seawater matrix interferes with ATP measurement. In this research, a 0.1 μm filtration process is introduced to eliminate such interferences. In addition, a filter rinsing step with sterilized artificial seawater is proposed to eliminate interference of free ATP. The ATP-filtration method is fast (<5 min), reproducible (VC = 7%), six times more sensitive than the direct ATP-method and correlates (R2 = 0.72, n = 100) with intact cell concentration. Microbial ATP concentration measured using the ATP-filtration method and the ATP-direct method were comparable. Microbial ATP measured along the treatment train of a full-scale seawater reverse osmosis (SWRO) plant decreased from 530 in the raw seawater to 10 ng-ATP/L after pre-treatment and to 0.5 ng-ATP/L in the SWRO permeate. The method was also applied to monitor bacterial growth potential (BGP) across the pre-treatment train of a (pilot) seawater desalination plant, where the removal of BGP through the media filtration and ultrafiltration was 44% and 7%, respectively. Highlights • A filtration-based method to measure microbial ATP in seawater was developed. • Microbial ATP can be measured without the interference of the seawater matrix. • The detection limit of the ATP-filtration method is 0.06 ng-ATP/L. • Microbial ATP measured using the ATP-filtration and ATP-direct methods correlated well. • Microbial ATP was applied in the pre-treatment and permeate of a full-scale SWRO plant. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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10. Biofouling performance of RO membranes coated with Iron NPs on graphene oxide.
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Armendáriz-Ontiveros, M.M., García García, A., de los Santos Villalobos, S., and Fimbres Weihs, G.A.
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FOULING , *GRAPHENE oxide , *CONTACT angle , *BIOFILMS - Abstract
Abstract Biofouling performance was evaluated for polyamide commercial RO membranes coated with iron nanoparticles (FeNPs) and graphene oxide (GO), under controlled conditions using a cross-flow system. Feed water obtained from the Sea of Cortez, Mexico, was pretreated, sterilized and inoculated with a high concentration (109 CFU mL−1) of Bacillus halotolerans MCC1, isolated from the Sea of Cortez. The zeta potential was determined for FeNPs and GO–FeNPs. XRD, roughness, contact angle, permeance and flux were determined for the coated and uncoated membranes. To evaluate the anti-biofouling effect, total organic carbon, total cell count, optical density and percentage of live/dead cells were determined for the biofilm. The GO–FeNP coating showed less agglomeration tendency and surface roughness compared to pure FeNP, and contact angle (49.1° ± 4.3°) similar to the uncoated membrane (50.2° ± 4.3°). Despite reducing the membrane permeance, the FeNP and GO–FeNP coatings presented larger fluxes after fouling (18% and 5.3% larger, respectively) than the fouled uncoated membrane. This was corroborated by both FeNP and GO–FeNP coated membranes presenting reduced biofilm layer thickness (89% and 65% thinner), total cell count (67% and 40% lower), optical density (40% and 48% lower) and total organic carbon (91% and 98% lower), than the uncoated membrane. Highlights • First biofouling study using native bacterium from Sea of Cortez • Accelerated biofouling testing done in cross-flow at high pressure • Use of ex-situ coating method to facilitate controlling the desired GO sheet size • Coated membranes increased fouled flux despite lower permeance • Iron nanoparticles can help reduce the amount of biofouling. [ABSTRACT FROM AUTHOR]
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- 2019
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11. Elimination of chemical products in the pre-treatment section of Las Palmas III reverse osmosis desalination plant to control fouling.
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Muñoz Elguera, A. and Pérez Báez, S.O.
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REVERSE osmosis (Water purification) , *SALINE water conversion plants , *FOULING , *SODIUM hypochlorite , *COAGULATION (Water purification) - Abstract
The paper analyses the extrapolation of the results obtained in a pilot plant to a full-scale seawater desalination plant. A technological system was implemented in the pre-treatment line of Las Palmas III seawater reverse osmosis (RO) desalination plant with a capacity of 36,000 m 3 /d. This system is aimed to control membrane fouling. It consists in the non-dosing of sodium hypochlorite or another biocide to seawater in order to minimize RO membrane biofouling. The pH regulation at 6.5 controls the scaling and the 12.5 ppm dosage of FeCl 3 as a coagulant maximizes the coagulation efficiency of colloidal particles and controls the fouling process. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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12. Synthesis, characterization and performance of polystyrene/PMMA blend membranes for potential water treatment.
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Bussi, Yonit, Golan, Shiri, Dosoretz, Carlos G., and Eisen, Moris S.
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POLYSTYRENE , *POLYMETHYLMETHACRYLATE , *POLYMERIC membranes , *CHEMICAL synthesis , *WATER purification - Abstract
PS membranes were prepared from polymeric blends of PS and PMMA via a phase inversion induced by an immersion precipitation in water coagulation baths. The effects of the casting parameters (e.g., solvent selection, the composition of the coagulation bath) and the type of polystyrene (substituents at the aromatic ring, tacticity) on the morphology and water permeation flux were studied. The findings reveal that modified PS promoting instantaneous demixing with NMP/water systems result in membranes wit- h macrovoids while the addition of 2% of PS-r-PMMA results in membranes with high water fluxes. The membranes morphologies were governed by a trade-off between thermodynamic and kinetic aspects. The antibacterial effect of (aPS) 70 -co-aPS(I) 30 /PMMA-based membrane was examined using static and cross-flow systems. These results illustrate the diversity in the design of these PS/PMMA based membranes and highlight the possibility to control the polymer chemistry for tailoring specific morphology, permeation, and antibacterial properties for the desired function. [ABSTRACT FROM AUTHOR]
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- 2018
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13. Effect of oxidation with coagulation and ceramic microfiltration pre-treatment on reverse osmosis for desalination of recycled wastewater.
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Myat, D.T., Roddick, F., Puspita, P., Skillman, L., Charrois, J., Kristiana, I., Uhl, W., Vasyukova, E., Roeszler, G., Chan, A., Zhu, B., Muthukumaran, S., Gray, S., and Duke, M.
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REVERSE osmosis (Water purification) , *SALINE water conversion , *CRYSTAL filters , *MICROFILTRATION , *WATER reuse - Abstract
Oxidation and coagulation before ceramic microfiltration (CMF) greatly increases membrane flux, but is unconventional for reverse osmosis (RO) pre-treatment. Impacts to RO and the wastewater recycling scheme operating CMF at high flux conditions is little understood. In this work, wastewater was treated with ozone or ultraviolet/hydrogen peroxide (UVH) oxidation, coagulation, then CMF, to explore RO membrane performance at bench scale. Sustainable high CMF fluxes were confirmed using coagulation with either ozone or UVH. Uniquely for ozone, dosing 13 mg-O 3 /L for 15 min greatly increased toxic by-product N -nitrosodimethylamine (NDMA) to 33 ng/L. Dosing chloramine (common for RO biofouling control) added only up to 7 ng/L NDMA. RO tests on all pre-treated waters showed little variation to flux but oxidation significantly altered texture of RO fouling material from smooth and dense to porous and granular. Biofouling studies with model bacteria strain RO 22 ( Pseudoalteromonas spp) showed higher organic biodegradability but biofilm analysis revealed ozone-coagulant-CMF greatly limited extension of bacteria communities from the membrane surface suggesting oxidation reduces RO biofouling. The novel findings of reduction of RO biofouling risk with oxidation and coagulation for high flux CMF pre-treatment identified in this work need to be demonstrated on different wastewater types over longer term. [ABSTRACT FROM AUTHOR]
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- 2018
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14. Applications of nisin for biofouling mitigation of reverse osmosis membranes.
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Jung, Yongmoon, Alayande, Abayomi Babatunde, Kim, In S., and Chae, Soryong
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NISIN , *REVERSE osmosis , *LACTOCOCCUS lactis , *BIOFILMS , *FOULING - Abstract
This study addresses the potential of application of nisin, a polycyclic antimicrobial peptide produced by Lactococcus lactis , as a novel biological agent for control/mitigation of biofilms formed by three different microorganisms: (i) Pseudomonas aeruginosa P60, (ii) Bacillus species, and (iii) a mixed culture of the two species. Nisin did not affect the growth rate of either strain, while the viability of Bacillus sp. was decreased, as compared to P. aeruginosa P60. Nisin was particularly effective for the dislodging of bacterial cells and extracellular polymeric substances (EPS) for P. aeruginosa P60. Water permeability of biofouled membranes was recovered by over 92% for all the bacterial strains investigated after nisin cleaning in a dead-end filtration system. Nisin has no detrimental effect on RO membrane and thus, has a potential as a biological agent for the mitigation of membrane biofouling. [ABSTRACT FROM AUTHOR]
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- 2018
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15. Ambivalent role of calcium in the viscoelastic properties of extracellular polymeric substances and the consequent fouling of reverse osmosis membranes.
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Ferrando, Diana, Kandiyote, Nitzan Shtreimer, Nejidat, Ali, Herzberg, Moshe, Toubiana, David, and Nguyen, Thanh H.
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CALCIUM , *VISCOELASTICITY , *REVERSE osmosis in saline water conversion , *FOULING , *POLYMERIC membranes - Abstract
The effects of polysaccharides composition on the interactions between EPS and RO membrane, including fouling, were studied in the presence of Ca 2 + . EPS originated from Pseudomonas aeruginosa PAO1 biofilms of the wild type and its Δ psl isogenic mutant was used for RO membranes fouling and QCM-D adsorption experiments. For the wild type strain EPS, bridging of alginates by Ca 2 + led to an increase in both adsorption and rigidity of the adsorbed layer. However, no change was detected for the Δ psl EPS adsorption and the obtained layer showed reduced rigidity, likely due to the interference of Ca 2 + with interactions between the polysaccharides composing the EPS. In agreement with the QCM-D results, once Ca 2 + was added, an increased in RO fouling was observed with the wild type EPS, while reduced fouling was found for the Δ psl mutant EPS. The presence of an ATR-FTIR peak characterized glycosidic linkage only for the fouling layer formed by the EPS of the Δ psl mutant in the presence of Ca 2 + , suggested that Ca 2 + alters the scaffold matrix of this EPS. The results of this study showed that polysaccharide composition in the EPS matrix significantly influences the interaction with Ca 2 + as well as membrane fouling. [ABSTRACT FROM AUTHOR]
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- 2018
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16. Combination of lauroyl arginate ethyl and nisin for biofouling control in reverse osmosis processes.
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Kim, Taek-Seung, Antoinette, Mikaela, and Park, Hee-Deung
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BIOCIDES , *FOULING , *REVERSE osmosis , *STAPHYLOCOCCUS aureus , *NISIN - Abstract
Lauroyl arginate ethyl (LAE) is a non-oxidizing biocide effective in controlling biofouling in reverse osmosis (RO) processes. However, the operating concentrations of LAE should be lowered to reduce the possible adsorption of LAE onto RO membranes and to reduce operational costs. This study investigated combinations of LAE with another non-oxidizing biocide, nisin, to overcome such practical limitation of LAE in a bench-scale RO unit operated with full recirculation with the model bacteria Staphylococcus aureus ATCC6538 and Pseudomonas aeruginosa PA14. Several combinations of LAE and nisin (e.g. 1 mg/L LAE + 2 mg/L nisin) were more effective in killing bacteria than LAE or nisin treatment alone, possibly due to permeability synergy. Furthermore, in a bench-scale RO unit operated with full recirculation and model bacteria, flux declines were more effectively moderated by dosing LAE and nisin together compared with the dosing of LAE or nisin alone. LAE dosing alone showed rapid flux decline in the early operational period, while nisin dosing alone demonstrated the lowest flux at the end of the operation. In conclusion, combinations of LAE and nisin appear more effective to mitigate biofouling developed on membranes than LAE or nisin alone. [ABSTRACT FROM AUTHOR]
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- 2018
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17. Laminar reduced graphene oxide membrane modified with silver nanoparticle-polydopamine for water/ion separation and biofouling resistance enhancement.
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Yang, Euntae, Alayande, Abayomi Babatunde, Kim, Chang-Min, Song, Jun-ho, and Kim, In S.
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LAMINAR flow , *GRAPHENE oxide , *MEMBRANE distillation , *SILVER nanoparticles , *SEPARATION (Technology) , *FOULING , *PERMEABILITY - Abstract
Laminar graphene oxide (GO) membranes with excellent water permeability have demonstrated great potential in the field of membrane-based water purification. However, low ion rejection and controversy over their biofouling propensity are hurdles GO membranes face in realizing commercial applications. This study shows that silver nanoparticle (nAg)@polydopamine (pDA) deposition on chemically reduced GO (rGO) laminates can simultaneously enhance both biofouling resistance and ion rejection. In pressurized filtration tests, the salt rejection of nAg@pDA-rGO membranes outperformed that of GO membranes despite its lowered water permeability. In osmotic filtration tests, nAg@pDA-rGO membranes achieved an increased water flux of 28.9 LMH and reduced reverse solute flux of 0.21 mol/m 2 ·h, compared to GO membranes. Moreover, extremely low cell attachment and viability were seen on the nAg@pDA-rGO membrane, confirming the excellent antibiofouling ability of nAg-pDA-rGO membranes. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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18. Inactivation of biofilms on RO membranes by copper ion in combination with norspermidine.
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Lee, Hye-Jin, Seo, Jiwon, Kim, Min Sik, and Lee, Changha
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FOULING , *SPERMIDINE , *BIOFILMS , *REVERSE osmosis in saline water conversion , *COPPER ions - Abstract
Biofouling is one of the most important factors that degrade the performance of reverse osmosis (RO) membranes during the desalination process. This study demonstrates that copper ion (Cu(II) or Cu(II) plus hydroxylamine (HA) to produce Cu(I)) in combination with norspermidine (Nspd) can effectively inactivate bacterial biofilms on RO membranes. The addition of Nspd inhibited the inactivation of planktonic P. aeruginosa cells by copper ion. However, with respect to the cells in biofilms (grown in CDC reactors), the use of Nspd enhanced the cell inactivation by copper ion; the addition of Nspd increased the inactivation efficacies of Cu(II) and Cu(II)/HA against biofilm cells from 2.4 to 3.1 and from 1.3 to 3.5 (log inactivation in 1 h), respectively. Nspd disrupted extracellular polymeric substances (as evidenced by the removal of proteins and polysaccharides from biofilms), and it is believed to facilitate the penetration of copper ion into the biofilm matrix. These results showed that the Cu(II)/HA/Nspd treatment also inactivated biofilms in pressurized cross-flow RO filtration units, resulting in partial recovery of permeate flux. However, pretreatment using Nspd (and the subsequent treatment by copper ion) was not as effective as the simultaneous use of Nspd and copper ion in both CDC reactors and cross-flow filtration units. [ABSTRACT FROM AUTHOR]
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- 2017
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19. Layer-by-layer self-assembly TiO2 and graphene oxide on polyamide reverse osmosis membranes with improved membrane durability.
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Shao, Feifei, Xu, Chunwei, Ji, Wenbiao, Dong, Hongzhou, Sun, Qiong, Yu, Liyan, and Dong, Lifeng
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TITANIUM dioxide , *GRAPHENE oxide , *MOLECULAR self-assembly , *REVERSE osmosis , *ARTIFICIAL membranes , *DURABILITY - Abstract
Improving membrane durability associated with resistance to chlorine and biofouling is critical important for polyamide (PA) reverse osmosis (RO) membrane technology. Here, few-layered TiO 2 nanoparticles and graphene oxide (GO) were layer-by-layer self-assembled onto flat PA reverse osmosis membrane surfaces by hydrogen bonding and physical absorption to address this challenge. Contact angle testing proved that the membrane surface hydrophilicity was improved with the increase of bilayers. The modified PA membrane with bilayer number ≤ 6 showed increased water flux. Moreover, XPS results indicated that TiO 2 and GO were attached to the membrane surface with good stability in our experimental conditions, and that GO nanoparticles played a part in improving chlorine resistance due to absorbing chlorine radicals. All modified PA membranes showed an anti-fouling effect and had an inhibitory effect on rejection reduction exposed to chlorine solution. For instance, the water flux of pristine membranes varied from 20.3 l/m 2 h to 7.5 l/m 2 h while the bilayer 6 -coated membrane dropped from 23.6 to 17.9 l/m 2 h after UV light exposure and incubating with microbial cells for 3 d. Meanwhile, for the chlorine resistance, compared with 60% salt rejection of unmodified membrane, the bilayer 6 -coated membrane was a more effective 75% after 20 h of chlorine exposure. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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20. Investigating the influence of organic matter composition on biofilm volumes in reverse osmosis using optical coherence tomography.
- Author
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Park, Sanghun, Nam, Taewoo, Park, Jongkwan, Kim, Soyeon, Ahn, Yujin, Lee, Sungyun, Kim, Young Mi, Jung, Woonggyu, and Cho, Kyung Hwa
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CARBON content of water , *REVERSE osmosis , *BIOFILMS , *WATER quality , *OPTICAL coherence tomography , *CROSS-sectional method - Abstract
Biofouling, a critical issue in membrane filtration, is influenced by several factors such as membrane characteristics and feed water quality. The organic matter (OM) composition is known to significantly influence biofilm formation, but few studies on this subject have been reported. Optical coherence tomography (OCT) allows direct monitoring of biofilm development on the membrane surface without the need for membrane autopsy. The purposes of the present study are 1) to quantify biofouling formation on a membrane surface using OCT; 2) to monitor the temporal variation of OM composition during membrane formation; and 3) to investigate the variation of OM composition. Substantial variations in thickness was observed from OCT images. It demonstrates that biovolume quantified from a single 2D cross-sectional image could result in inaccurate quantification. Here, we quantified foulants on the membrane surface using 3D images and validated the results using confocal laser scanning microscopy (CLSM). As well, variations in the OM composition driven by bacterial activity were observed by fluorescence excitation–emission matrix analysis and size exclusion chromatography. The biovolume estimated by the OCT system was 103.7 μm 3 /μm 2 . CLSM demonstrated that 10% of the foulants on the membrane surface was composed of live and dead bacteria. [ABSTRACT FROM AUTHOR]
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- 2017
- Full Text
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21. Gravity-driven microfiltration pretreatment for reverse osmosis (RO) seawater desalination: Microbial community characterization and RO performance.
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Wu, Bing, Suwarno, Stanislaus Raditya, Tan, Hwee Sin, Kim, Lan Hee, Hochstrasser, Florian, Chong, Tzyy Haur, Burkhardt, Michael, Pronk, Wouter, and Fane, Anthony G.
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MICROFILTRATION , *REVERSE osmosis (Water purification) , *SALINE water conversion , *MICROBIAL communities , *EUKARYOTES , *ULTRAFILTRATION - Abstract
A pilot gravity-driven microfiltration (GDM) reactor was operated on-site for over 250 days to pretreat seawater for reverse osmosis (RO) desalination. The microbial community analysis indicated that the dominant species in the pilot GDM system (~ 18.6 L/m 2 h) were completely different from those in the other tested GDM systems (~ 2.7–17.2 L/m 2 h), operating on the same feed. This was possibly due to the differences in available space for eukaryotic movement, hydraulic retention time (i.e., different organic loadings) or operation time (250 days vs. 25–45 days). Stichotrichia , Copepoda , and Pterygota were predominant eukaryotes at genus level in the pilot GDM. Furthermore, the GDM pretreatment led to a significantly lower RO fouling potential in comparison to the ultrafiltration (UF) system. This was attributed to the fact that GDM filtration produced a permeate with less amount of assimilable organic carbon (AOC) and biopolymers. Accordingly, lower amount of organic foulants (biopolymers and low molecular weight neutrals) and less biofilm formation on the GDM-RO membrane were observed. Although α-proteobacteria were dominant in both RO fouling layers, their bacterial community compositions at genus level were significantly different. Thalassobius had higher abundance in the GDM-RO fouling layers, while Erythrobacter and Hyphomonas were more predominant in the UF-RO fouling layers. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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22. The application of electromagnetic fields to the control of the scaling and biofouling of reverse osmosis membranes - A review.
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Piyadasa, Chathuri, Ridgway, Harry F., Yeager, Thomas R., Stewart, Matthew B., Pelekani, Con, Gray, Stephen R., and Orbell, John D.
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ELECTROMAGNETIC fields , *FOULING , *REVERSE osmosis , *BIOCIDES , *HALOGENS , *HEAT exchangers - Abstract
Scaling and biofouling are two major problems in the operation of reverse osmosis (RO) membranes. A variety of control measures are employed in practice, including the use of pulsed electromagnetic fields (EMF), which can avoid the use of chemical anti-fouling agents (e.g. halogen-based biocides) that may be toxic to humans or the environment. This is a fairly recent and controversial technology and, from the available documentation and literature, it is clear that the scientific basis for its purported effectiveness is not yet firmly established, although some studies suggest that beneficial effects could be possible. In particular, the various conditions under which EMF technologies are likely to be effective for real world applications have not been scientifically established. This review collates the relevant literature on the problem of scaling and biofouling in RO membranes and heat exchangersystems (e.g. cooling towers), with a particular focus on the application of pulsed EMF technologies, including the broad documentation, relevant scientific studies, proposed mechanisms of action and further research directions. This review demonstrates that a lot more systematic scientific research is needed in order to validate the application and commercialization of EMF technologies as a pretreatment to control fouling in RO membrane systems. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
23. Organic carbon movement through two SWRO facilities from source water to pretreatment to product with relevance to membrane biofouling.
- Author
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Alshahri, Abdullah H., Dehwah, Abdullah H.A., Leiknes, TorOve, and Missimer, Thomas M.
- Subjects
- *
WATER purification , *FOULING , *ORGANIC compounds , *BACTERIAL growth , *REVERSE osmosis - Abstract
The presence of algae, bacteria, various fractions of natural organic matter (NOM), and transparent exopolymer particles (TEP) in the raw water, after each pretreatment process and in the permeate and concentrate streams, were measured at two SWRO plants to assess biofouling potential. It was found that the most significant process controlling the concentration of algae, bacteria, and the biopolymer and humic substances was the intake type with the subsurface intake discharge showing significant reductions. The mixed media filtration process was marginally useful in removing some TOC and NOM, but had little effect on TEP removal. Some bacterial regrowth may be occurring in the cartridge filters, but the evidence is inconsistent. Significant quantities of the biopolymer and humic substance concentrations were found to be retained in the membranes, but the concentrations were significantly greater in the facility using an open-ocean intake. Bacteria and TEP were found in the permeate stream, which may document bacterial regrowth and TEP production downstream of the membrane process. Measurements of the organic carbon passage through SWRO facilities can be successfully used to evaluate pretreatment process effectiveness and to make SWRO plant operational improvements. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
24. Optimizing UVC-disinfection using LEDs as an energy efficient pre-treatment for biofouling control in spiral-wound membrane systems.
- Author
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Sperle, P., Khan, M.S., Skibinski, B., Wurzbacher, C., and Drewes, J.E.
- Subjects
- *
FOULING , *REVERSE osmosis , *MICROBIAL inactivation , *BATCH reactors , *BIOFILMS - Abstract
Biofouling remains a major challenge for reverse osmosis (RO) systems. Pulsed ultraviolet (UV) pre-treatment has been proposed as a mitigation strategy for biofouling control of RO membranes. This study investigated whether increasing fluence rate during pulsed UV disinfection leads to enhanced inactivation. Further, UV irradiation from 1.5 to 61.3 mJ cm−2 was tested for optimal biofouling control. Therefore, an UVC-LED reactor was characterized by successfully adapting an actinometry method for flow-through mode. The inactivation of microorganisms was compared in flow-through biodosimetry experiments in pulsed and continuous irradiation. Finally, several settings were applied as pre-treatment in lab-scale biofouling experiments and membrane performance and biofilm removability elucidated. Whereas no enhanced inactivation was observed during biodosimetry experiments, pulsed UV disinfection resulted in an average of 20.6 % increased delay of biofilm formation. On the contrary, for pulsed UV disinfection, the biofilm hydraulic resistance seemed higher than continuous equivalents, but not significantly. Overall, savings of operational expenditures per fluence applied was highest around 4 mJ cm−2. UV pre-treated biofilms showed no enhanced removability, but delay in biofilm formation was noticeable in two of three experiments. In case the effects translate to up-scaled applications over several cleanings, UV pre-treatment for biofouling control is an interesting option. [Display omitted] • A new actinometric method was adapted from batch to flow-through reactor. • Pulsed UV disinfection with increased fluence rate showed no enhanced inactivation. • Delay of biofilm formation depends on fluence but shows tailing at higher fluence. • Highest operational expenditure savings normalized to fluence were at ~4 mJ cm−2. • UV did not affect biofilm removal, but delay after CIP needs further investigation. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
25. Polyelectrolyte-assisted interfacial polymerization for polyamide nanofiltration membrane with enhanced separation and anti-biofouling properties in groundwater treatment.
- Author
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Mei, Ying, Yang, Zhe, Sun, Peng-Fei, Zhou, Shenghua, Guo, Hao, Peng, Lu Elfa, Yao, Zhikan, Yang, Wulin, and Tang, Chuyang Y.
- Subjects
- *
POLYAMIDE membranes , *MEMBRANE separation , *GROUNDWATER purification , *COMPOSITE membranes (Chemistry) , *POLYMERIZATION , *INTERFACIAL reactions , *PERFLUOROOCTANE sulfonate , *PIPERAZINE , *POLYAMIDES - Abstract
We proposed a facile method of using polyelectrolyte additive to tune interfacial polymerization reaction and tailor polyamide NF membrane with better separation performance and lower bio-fouling potential for groundwater treatment. A moderate concentration of negatively charged poly(4-styrene sulfonate) (PSS) was introduced to the aqueous phase solution during the interfacial polymerization of piperazine (PIP) and trimesoyl chloride (TMC). The presence of PSS hindered the diffusion of PIP, leading to the formation of polyamide layer with a looser structure, increased thickness, and additional negative charges on the membrane surface. The fabricated TFC-P 6 membrane possessed enhanced water permeance (21.8 ± 0.7 L m−2 h−1 bar−1) and better selectivity (α = 11.5 ± 1.0) of calcium chloride over sodium sulfate which can be beneficial to achieve higher water recovery compared to the control TFC membrane. In addition, the TFC-P 6 membrane demonstrated enhanced rejection of perfluorooctane sulfonate (~95 %) and the biofouling was inhibited by its additional negative charge and smoother surface. Our results introduced a robust and scalable strategy of polyelectrolyte-assisted interfacial polymerization for designing high performance NF membranes in groundwater treatment. • Negatively charged polyelectrolyte was applied as an additive to the aqueous solution during interfacial polymerization. • PSS hindered the diffusion of piperazine. • TFC membrane fabricated with the aid of PSS showed enhanced water permeance and higher selectivity of CaCl 2 over Na 2 SO 4. • The TFC membrane fabricated with the modified recipe demonstrated higher rejection of PFOS and reduced bio-fouling potential. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
26. Photo-Fenton catalytic anti-fouling membranes for efficient elimination of radionuclides and organic contaminants.
- Author
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Ye, Daping, Gao, Qian, Li, Ting, Wu, Xilong, and Wu, Yundi
- Subjects
- *
POLLUTANTS , *RADIOISOTOPES , *SEWAGE disposal , *TANNINS , *BACTERIAL inactivation , *CHEMICAL resistance , *URANIUM compounds , *COMPOSITE membranes (Chemistry) - Abstract
The complexity of nuclear industry effluents necessitates novel treatment capable of facilitating water recycling and byproduct recovery. Many membrane-based technologies have become increasingly important for sewage water disposal because of their simple operation and scale-up for industrial applications. However, the membrane biofouling due to microbial attachment has become a serious issue, resulting in decreased removal efficiency for radionuclides and organic pollutants. Herein, by immobilizing the hybrid tannic acid (TA)/zero-valent iron (ZVI) nanostructures (TZ) onto the blow-spun amidoximed polyacrylonitrile (AOP)/zeolitic imidazolate framework-90 (ZIF-90) composite nanofibers, the ultimate AOP/ZIF-90@TA/ZVI (AZ@TZ) membranes with covalently cross-linked coatings were fabricated for synergistic adsorption-chemical reduction of uranium, photo-Fenton catalytic degradation of organic dyes, and ZVI/Zn2+-mediated resistance against bacterial cells. In order to assess the membrane's efficacy in eliminating uranium ions, a series of studies involving adsorption behavior were performed. The antibacterial and antifouling tests were further carried out using typical bacteria and organic dyes. The AZ@TZ hybrid membranes exhibited high uptake kinetics and the elimination capacity of uranium (140.06 mg/g) at pH 5.0, as well as excellent properties for photodegradation of organic dyes and inactivation of the bacteria within the biofilms. The novel integrated photo-Fenton and membrane-based technique offers fresh ideas for extremely effective radioactive sewage disposal. • High uranyl removal by the O-, N-atoms-coordination and chemical reduction • AZ@TZ membrane for photocatalytic degradation of dyes by excessive •OH radicals • Synergistic uranium immobilization, dye degradation, and antimicrobial activities [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
27. Quorum sensing-Fe metabolism interplay affects biofouling on reverse osmosis membrane: Evidences from microbial shift and structure alteration.
- Author
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Li, Yufang, Wang, Shu, Ding, Haojie, Xiao, Kang, and Huang, Xia
- Subjects
- *
REVERSE osmosis , *FOULING , *QUORUM sensing , *REVERSE osmosis process (Sewage purification) , *METABOLISM , *MICROBIAL communities , *COAGULANTS - Abstract
Iron fouling induced by residual Fe(III) was frequently reported in reverse osmosis operation. However, previous studies mainly focused on inorganic precipitation or Fe-organics coupling, yet ignoring its potential effects on microbes. In this study, by using ultrafiltration effluent (~2.3 mg/L Fe(III)) as the feed, a long-term fouling experiment was conducted to investigate how excessive Fe influenced biofouling. Results showed, under continuous stresses of Fe-deposits (eventually >40 μg/cm2), fouling development clearly exhibited a three-stage process, where Fe-metabolism, extracellular polymeric substance synthesis and quorum sensing (QS) were intricately intertwined. Compared to Early (3 h–2 d) and Developed (4 d–10 d) Stage, ecological interaction network in Mature Stage (12 d–30 d) was shifted and highly modularized, with iron-depositing genera (such as Leptothrix) in emerging Fe-metabolic modules as the core nodes. Foulant structure was also more porous. Moreover, by detecting signal molecules, the upregulation of QS was unraveled. Functional gene co-occurrence analysis further revealed the profound involvement of QS in enhancing polysaccharides (PS) secretion and ferric-reduction, which were verified by the constantly rising PS proportion and Fe(II)/Fe(III) ratio on surface. Therefore, more attentions should be paid to residual Fe-issues, as it not only affected inorganic fouling, but also significantly altered biofouling behaviors. [Display omitted] • Residual Fe from excessive dosage of ferric coagulants affected membrane fouling. • Under Fe-stresses, microbial community shifted and experienced three stages. • Fe metabolism related functional modules were formed during dynamic fouling. • Fe metabolism, EPS synthesis and quorum sensing function intertwined together. • Thickening biofilm grew more porous after the upregulation of quorum sensing. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
28. Atomic force microscopy study of the biofouling and mechanical properties of virgin and industrially fouled reverse osmosis membranes.
- Author
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Powell, L.C., Hilal, N., and Wright, C.J.
- Subjects
- *
ATOMIC force microscopy , *REVERSE osmosis , *FOULING , *POLYAMIDES , *ELASTICITY , *ADHESION - Abstract
The mechanical properties of virgin and industrially fouled reverse osmosis membranes (composite polyamide) used for the purification and desalination of seawater in desalination processes were characterised using novel atomic force microscopy (AFM) methods. Polymeric surface elasticity has previously been demonstrated to strongly affect the adhesion of bacteria; hence the study examined membrane surface elasticity to demonstrate how AFM can be used to assess the bio-fouling potential of membranes. An AFM colloid probe technique was used to determine the mechanical properties of the membrane, the adhesion forces and the work of adhesion at the membrane surfaces. The mean values of Young's modulus for the virgin membrane decreased in magnitude with increasing pH values, where these values were significantly different ( p < 0.017) between both pH 3 (1450 kPa), pH 7 (1327 kPa) and pH 9 (788 kPa). These differences were attributed to differences in membrane swelling and indicate possible control parameters that could be exploited to improve membrane cleaning regimes. A membrane with a higher modulus will be stronger and potentially more resistant to chemical and physical processes during operation and cleaning. Significant differences ( p < 0.017) in force measurements were also found between different electrolytic conditions for each of the membranes, where for the virgin membrane the adhesion force values were 6.00 nN at pH 3, 1.77 nN at pH 7 and 0.98 N at pH 9, and also the work of adhesion were 153.6 nJ at pH 3, 22.8nJ at pH 7 and 9.9 nJ at pH 9 in 0.6 M NaCl. These observations further confirm the importance of the electrolytic environment on the nanoscale interactions of the membrane which should be considered to control fouling during operation and cleaning cycles. AFM images and streaming potential measurements of virgin and fouled membranes were also obtained to aid analysis of the industrial membrane system. The novel application of AFM to membranes to measure Young's moduli and work of adhesion is a new addition to the AFM tools that can be used to unravel separation processes at the membrane surface. In addition, this study further demonstrates that AFM force spectroscopy can be used as part of a sophisticated membrane autopsy procedure for the elucidation of the mechanisms involved in membrane fouling. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
29. The involvement of lectins and lectin-like humic substances in biofilm formation on RO membranes - is TEP important?
- Author
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Winters, Harvey, Chong, T.H., Fane, Anthony G., Krantz, William, Rzechowicz, Miles, and Saeidi, Nazanin
- Subjects
- *
HUMUS , *BIOFILMS , *REVERSE osmosis , *PROTEINS , *LECTINS , *SALINE water conversion - Abstract
There are significant number of publications that state that the main cause of biofilm formation and organic fouling on reverse osmosis (RO) membranes is due to the presence of transparent exopolymer particles (TEP) and their precursors. Alcian Blue has been used to detect and quantify TEP and their precursors. However, Alcian Blue is not specific for TEP substances and interacts with other acidic substances, lectin-like humic substances which may also be important in biofilm formation and chemical conditioning of membrane surfaces. Certain lectin-like humic substances may be present in RO feed waters. A new assay procedure which couples, ammonium sulfate protein precipitation, LC-OCD and Alcian Blue is presented which can detect and quantify these lectin-like humics in any water sample. It appears that bio-adhesion is dependent upon these lectin-like humics and they appear to control biofilm formation. Based on results from a wastewater RO reclamation facility and examination of the literature, the presence and importance of TEP and their precursors in biofilm formation may be overstated and that biofilm and/or organic fouling on RO membranes appears to be initiated and controlled by the presence of certain lectin-like humics which may not be the dominant conditioning mechanisms in every RO desalination plant. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
30. Highly improved reverse osmosis performance of novel PVA/DGEBA cross-linked membranes by incorporation of Pluronic F-127 and MWCNTs for water desalination.
- Author
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Falath, Wail, Sabir, Aneela, and Jacob, Karl I.
- Subjects
- *
REVERSE osmosis (Water purification) , *ARTIFICIAL membranes , *MULTIWALLED carbon nanotubes , *POLYVINYL alcohol , *SALINE water conversion , *POLYMER films - Abstract
A novel Poly (vinyl alcohol) (PVA) reverse osmosis (RO) membrane with unique performance and characteristics was synthesized for water desalination. PVA thin film nanocomposite (TFN) membranes were fabricated by the infusion of Pluronic F-127 and multi-wall carbon nano-tubes (MWCNTs) in a single layer crosslinked by bisphenol A diglycidyl ether (DGEBA). The overall RO performance of the membranes including hydrophilicity, surface roughness, water permeability, salt rejection, chlorine resistance and biofouling resistance was evaluated using a dead end RO filtration unit. The incorporation of Pluronic F-127 and MWCNTs improved the overall RO performance of the membranes. It was found that the modified membranes surface became smoother and highly hydrophilic compared to the pristine PVA membranes surfaces. This study indicated that the membranes that contain 0.08 and 0.1 wt% MWCNTs provided excellent permeation, salt rejection, Chlorine and biofouling resistance and mechanical strength. The most striking result to emerge from this study is that the overall RO performance enhancement has transpired while utilizing PVA as an active RO separation layer without a polymeric or ceramic substrate. This study shows that proper crosslinking of PVA coupled with mechanical strength enhancement overcomes the common PVA drawbacks, mainly swelling and rupture under very high pressure. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
31. Inhibiting quorum sensing pathways to mitigate seawater desalination RO membrane biofouling.
- Author
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Katebian, Leda, Gomez, Edgar, Skillman, Lucy, Li, Dan, Ho, Goen, and Jiang, Sunny C.
- Subjects
- *
QUORUM sensing , *SALINE water conversion , *REVERSE osmosis (Water purification) , *ARTIFICIAL membranes , *FOULING - Abstract
Bacterial biofilm formation, the main cause of membrane biofouling, is a crucial issue for membrane separation. Biofilm production is regulated by quorum sensing (QS) systems where bacteria secrete auto-inducers to communicate with neighboring bacteria. This research identified that several marine bacteria isolated from a desalination plant produced a low molecular weight auto-inducer 1 (AI-1) signaling molecule. AI-1 production in the mixed culture of the four different biofilm-forming marine bacteria was greater than in individual bacterial cultures. The QS inhibiting compounds, vanillin and cinnamaldehyde at 1200 mg/L significantly reduced biofilm formed by these marine bacteria by more than 79% and 70%, respectively in a microtiter plate assay. Anti-biofilm capabilities of vanillin and cinnamaldehyde were further assessed in a reverse osmosis membrane bio-monitoring system using mixed bacterial cultures and native uncultured bacterial communities in natural seawater. Confocal microscopy showed vanillin (1200 mg/L) significantly reduced biofilm extracellular polysaccharides and dead cells on the membrane surface (> 40%, > 20%). These results indicate that QS inhibitors have the potential to remediate membrane biofouling. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
32. Evaluation of inhibitors and biocides on the corrosion, scaling and biofouling control of carbon steel and copper–nickel alloys in a power plant cooling water system.
- Author
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Rahmani, Kh., Jadidian, R., and Haghtalab, S.
- Subjects
- *
CHEMICAL inhibitors , *BIOCIDES , *CARBON steel corrosion , *FOULING , *COPPER-nickel alloys , *POWER plants , *COOLING systems - Abstract
Corrosion, scaling and biofouling are three problems in the power plant cooling system. In this paper, the influence of inhibitors and biocides on control of these problems for mild steel and copper–nickel alloys in a power plant cooling water system was investigated. The results showed that alone sodium hypochlorite (NaClO) in the presence of 1-Hydroxyethylidene-1,1-Diphosphonate (HEDP), maleic anhydride homopolymer (HPMA), 2-phosphonobutane-l,2,4-tricarboxylic acid (PBTC) as scaling inhibitors, and ZnSO 4 , 2-Mercaptobenzothiazole (MBT) as corrosion inhibitors was not effectively reduced corrosion, scaling and biofouling. In the presence of Alkyl Dimethyl Banzil Ammonium Chloride, one of the Quaternary Ammonium Compounds (QACs), the inhibition efficiency was increased. The effects of inhibitors on carbon steel copper–nickel were studied through electrochemical and weight loss measurement. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
33. Biofouling suppression of modified feed spacers: Localized and long-distance antibacterial activity.
- Author
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Ronen, Avner, Resnick, Ayal, Lerman, Sofia, Eisen, Moris S., and Dosoretz, Carlos G.
- Subjects
- *
FOULING , *ANTIBACTERIAL agents , *AMMONIUM , *COVALENT bonds , *SONOCHEMISTRY , *ATOM transfer reactions - Abstract
Biofouling hindering activity of two modified feed spacers was assessed. A ‘short-distance’ modification was attained by covalently binding polymeric quaternary ammonium groups (pQAs) to the spacer by atom transfer radical polymerization (ATRP). A ‘long-distance’ modification was based on embedding silver nanoparticles (nAg) in the polymeric spacer by sonochemical deposition. Cross-flow experiments in planar-membrane filtration cells using ultrafiltration membranes exposed to a mixed microbial enrichment were performed at conditions simulating spiral wound modules (0.15 m·s − 1 channel flow velocity). Physical properties of the modified spacers were evaluated using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy. Microscopic analysis of the membranes adjacent to the modified spacers indicated the presence of a sporadic monolayer structure compared to a developed biofilm in the untreated spacers. SEM imaging and total organic carbon analysis of the attached layer revealed a low number of bacteria near the modified spacers and adjacent membranes. Both modified spacers displayed improved permeate fluxes compared to the control. nAg modified spacers displayed a somewhat steadier permeate flux profile within the length of the experiments probably due to the release of antibacterial active species. pQA modified spacers are assumed to have a more localized influence by direct contact on their surface. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
34. Nanomaterials for biofouling and scaling mitigation of thin film composite membrane: A review.
- Author
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Ong, C.S., Goh, P.S., Lau, W.J., Misdan, N., and Ismail, A.F.
- Subjects
- *
NANOSTRUCTURED materials , *FOULING , *COMPOSITE membranes (Chemistry) , *THIN films analysis , *SEWAGE purification - Abstract
Biofouling and scaling are commonly encountered bottlenecks in large and small scale installations of membrane technology for surface-, waste- or seawater treatment. The phenomena can pose persistent operational challenge with substantial economic impacts if they are left unresolved. Effort has been made to reduce the tendency of these detrimental phenomena by improving membrane properties, optimizing operational conditions as well as establishing reliable pretreatment of the feed water. This review places a main focus on the recent advances of low biofouling and scaling thin film composite (TFC) membranes that are incorporated with different types of nanomaterials. In this contribution, the biofouling and scaling phenomena and their negative effects on TFC membranes are first discussed. The recent studies on the preparation of low biofouling and anti-scaling TFC membrane using different nanomaterials are then critically summarized. Current challenges to enhance membrane long-term stability, reliability, and cost efficiency are also highlighted. The applications of nanomaterials in membrane desalination are anticipated to improve resistance properties of TFC membranes against biofouling and scaling and further foster the innovation of sustainable membrane desalination technology. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
35. In situ surface functionalization of reverse osmosis membranes with biocidal copper nanoparticles.
- Author
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Ben-Sasson, Moshe, Lu, Xinglin, Nejati, Siamak, Jaramillo, Humberto, and Elimelech, Menachem
- Subjects
- *
REVERSE osmosis in saline water conversion , *COPPER , *METAL nanoparticles , *FOULING , *ANTIBACTERIAL agents , *X-ray photoelectron spectroscopy - Abstract
Biofouling may lead to severe operational challenges that can significantly impair membrane desalination processes. In recent years, copper-based nanoparticles (Cu-NPs) have gained increased attention as a potentially viable anti-biofouling agent in membrane processes, due to their strong antibacterial activity and relatively low cost. This study presents a novel and facile method to attach biocidal Cu-NPs on the surface of a thin-film composite reverse osmosis membrane. Herein, we suggest a method for membrane surface functionalization with Cu-NPs that is performed without disassembling the membrane module, which highlights its practicality and potential application for reverse osmosis desalination plants. The loading of Cu-NPs on the membrane was confirmed both by scanning electron microscope imaging and X-ray photoelectron spectroscopy analysis, indicating that the deposited nanoparticles were composed of either metallic copper or copper-oxide. The impact of the in situ Cu-NP modification on membrane transport properties was found to be minor, with only a slight increase of the water and salt permeability. Furthermore, except for a slight increase in hydrophobicity, the modified membrane exhibited surface properties comparable to those of the pristine membrane. Finally, the in situ formed Cu-NPs imparted a strong antibacterial activity to the membrane surface, leading to 90% reduction in the number of attached live Escherichia coli bacteria on the modified membrane compared to the pristine reverse osmosis membrane. This study demonstrates that in situ grafting of Cu-NPs on reverse osmosis membranes is a potential alternative to reduce biofouling. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
36. Effective in-situ chemical surface modification of forward osmosis membranes with polydopamine-induced graphene oxide for biofouling mitigation.
- Author
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Hegab, Hanaa M., ElMekawy, Ahmed, Barclay, Thomas G., Michelmore, Andrew, Zou, Linda, Saint, Christopher P., and Ginic-Markovic, Milena
- Subjects
- *
GRAPHENE oxide , *OSMOSIS , *ARTIFICIAL membranes , *DOPAMINE , *SURFACE chemistry , *FOULING - Abstract
The superior biocidal properties of graphene oxide (GO) nanosheets have enabled their recent application in novel antifouling coatings for membrane filtration. Nevertheless, a practical method for attaching the GO nanosheets to the membrane surface remains a big challenge. This work presents a new methodology for achieving an optimized process for incorporating GO nanosheets onto the surface of thin-film composite (TFC) FO membranes using the bioadhesive polydopamine (pDA). The pDA deposition occurs through self-assembly and oxidative polymerization, both reducing the GO nanosheets and immobilizing them onto the membrane surface. Taguchi's statistical experimental design was used to optimize the process conditions to satisfy the simultaneous enhancement of water flux, reverse solute flux selectivity and antibiofouling performance. Compared to an unmodified membrane the optimum membrane modification both improved pure water flux (21.5%) and reverse solute flux selectivity (80%) and greatly extended the onset of biofouling due to remarkable bactericidal properties. The superior performance of GO-pDA modified membrane in all aspects illustrates its strong potential for application to industrial FO membranes. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
37. Advanced organic and biological analysis of dual media filtration used as a pretreatment in a full-scale seawater desalination plant.
- Author
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Jeong, Sanghyun, Vollprecht, Robert, Cho, Kyungjin, Leiknes, TorOve, Vigneswaran, Saravanamuthu, Bae, Hyokwan, and Lee, Seockheon
- Subjects
- *
SALINE water conversion , *FOULING , *PYROSEQUENCING , *BACTERIAL communities , *BIOFILTRATION - Abstract
Dual media filter (DMF) is being used as a primary pretreatment to remove particulate foulants at seawater desalination plants. However, many plants experience organic and biological fouling. The first part of this paper focuses on the monitoring of organic and biological foulants using advanced analytical techniques to optimize functioning of DMF at Perth Seawater Desalination Plant (PSDP) in Western Australia. In addition, microbial community analysis in DMF filtered seawater, and on DMF media (DMF-M) and cartridge filter (CF) was conducted using terminal restriction fragment length polymorphism (T-RFLP) and 454-pyrosequencing. In the full-scale DMF system, the bacterial community structure was clustered along with the filtration time and sampling positions. For the DMF effluent samples, the bacterial community structure significantly shifted after 4 h of filtration time, which corresponded with the permeability reduction trend. The dominant bacterial communities in the DMF effluent were OTU 13 (Phaeobacter) and OTU 19 (Oceaniserpentilla). The different biofilm-forming bacteria communities were found in the biofilm samples on DMF-M and CF. In the second part of the study, semi-pilot scale DMF columns were operated on-site under same operating conditions used in PSDP. It demonstrated the advantage of operating DMF at the biofiltration mode for improving the reduction of biofoulants. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
38. Culturable bacteria from a full-scale desalination plant: Identification methods, bacterial diversity and selection of models based on membrane-biofilm community
- Author
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Lucy Skillman, Zhangwang Xie, Veena Nagaraj, Goen Ho, and Dan Li
- Subjects
biology ,Mechanical Engineering ,General Chemical Engineering ,Microbacterium ,Pseudomonas ,Biofilm ,02 engineering and technology ,General Chemistry ,021001 nanoscience & nanotechnology ,biology.organism_classification ,Desalination ,Biofouling ,Pseudoalteromonas ,020401 chemical engineering ,Botany ,General Materials Science ,0204 chemical engineering ,0210 nano-technology ,Relative species abundance ,Bacteria ,Water Science and Technology - Abstract
Bacterial models representative of a full-scale system are important requisites of biofouling studies. In this study, bacteria from upstream locations and from RO membranes were cultured and compared, using three identification methods, mainly to determine species-similarities and furthermore, to assess biochemical similarities between organisms from the upstream planktonic community and RO membranes, even if their taxonomy was not identical. Sixty-four bacterial strains from different locations of the Perth Seawater Desalination Plant, were isolated. There were similarities in species as well as carbon-source utilisation abilities of key models between cultures from upstream locations and membrane-biofilms. Pseudoalteromonas and Microbacterium were the most versatile in their metabolic abilities. Isolates were compared with the genetic biofilm communities on fourteen RO membrane units fouled over 7 years, from the full-scale plant [1]. Model fouling bacteria were selected based on their relative abundance in both culture and community profiles, phylogenetic and biochemical diversity. Bacteria from thirteen different genera were selected as models for exopolysaccharide-characterisation and biofouling studies, among which Pseudomonas and Bacillus were the most prevalent in both cultures and genetic biofilm community.
- Published
- 2019
- Full Text
- View/download PDF
39. Understanding fouling dynamics on functionalized CNT-based membranes: Mechanisms and reversibility
- Author
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Muhammad Usman Farid, Alicia Kyoungjin An, and Noman Khalid Khanzada
- Subjects
chemistry.chemical_classification ,Fouling ,Mechanical Engineering ,General Chemical Engineering ,02 engineering and technology ,General Chemistry ,Carbon nanotube ,021001 nanoscience & nanotechnology ,Polyvinylidene fluoride ,law.invention ,Biofouling ,chemistry.chemical_compound ,Membrane ,020401 chemical engineering ,chemistry ,Chemical engineering ,law ,Humic acid ,General Materials Science ,0204 chemical engineering ,0210 nano-technology ,Porosity ,Layer (electronics) ,Water Science and Technology - Abstract
Herein, we explored resistance to fouling and the bactericidal potential of a functionalized carbon nanotube (CNT)-based polyvinylidene fluoride (PVDF) membrane. Humic acid (HA), a main constituent in natural organic matter was used as an indicator for the estimation of organic fouling, while Escherichia coli was employed as a model bacterium for biofouling investigation. In-situ fouling characterization was performed using a non-destructive optical coherence tomography. Results revealed that a thin CNT layer on the PVDF surface effectively prevented HA molecules from interacting directly with the porous structure of membrane, thereby averting the possibility of pore blockage (irreversible fouling). Moreover, the CNT membranes offered higher permeability, increased HA rejection, and better flux restoration capacity as compared with pristine PVDF membrane. This superior anti-HA-fouling performance of CNT membrane was accredited to the electrostatic repulsions between the CNT layer and HA molecules, both carrying a strong negative charge and high density of hydrophilic functional groups on the CNT surface. Antibacterial results from the ultrastructural examination of cell membrane integrity authenticate the bactericidal potential of CNT membrane toward biofouling causing bacteria. Finally, when tested with real sea water, CNT membrane with less organic and biofouling propensity outperformed commercial PVDF, indicating their suitability for seawater reverse osmosis (SWRO) pretreatment.
- Published
- 2019
- Full Text
- View/download PDF
40. Microbial interaction energy and EPS composition influenced ultrafiltration membrane biofouling and the role of UV pretreatment.
- Author
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Hu, Haotian, Lu, Zhili, Wang, Haibo, Yin, Hong, Hao, Haotian, Ma, Baiwen, and Shi, Baoyou
- Subjects
- *
FOULING , *WATER treatment plants , *COMPUTATIONAL fluid dynamics , *MEMBRANE separation , *POLYSACCHARIDES , *FOULING organisms , *ULTRAFILTRATION - Abstract
Biofouling is still an important factor limiting ultrafiltration further application, and previous mechanism analyses were mainly focused on extracellular polymeric substances (EPS) composition and concentration. In this study, both biofouling and alleviation mechanisms were further investigated in detail with three typical microorganisms, particularly toward the microbial interaction energy. The results showed that a stronger fouling degree was induced by Pseudomonas putida (rod-shaped) than that induced by Staphylococcus aureus and Enterococcus faecalis (sphere). The computational fluid dynamics results suggested that the larger membrane filtration resistance caused by P. putida was due to more EPS secretion. EPS composition and confocal laser scanning microscopy analysis indicated that polysaccharide in EPS played greater roles on the biofouling than protein. According to the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, higher interaction energy was induced because of higher content of polysaccharide (e.g., hydroxyl groups) and protein (e.g., aggregated strands of amide I band) in EPS from P. putida , resulting in a thicker biofilm and stronger biofouling degree than that caused by S. aureus and E. faecalis. In addition, both EPS secretion and microbial interaction energy were inhibited by UV pretreatment, resulting in fouling alleviated. This work will be beneficial for further biofouling control in actual water treatment plants. [Display omitted] • Pseudomonas putida induced severe UF membrane fouling due to high content of EPS. • The polysaccharide composition in EPS was mainly contributed to the fouling degree. • Polysaccharide and protein showed good relation with microbial interaction energy. • The microbial interaction energy was positively correlated with fouling degree. • UV reduced biofouling by both restraint of EPS secretion and microbial interaction. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
41. Microbial deposition and growth on polyamide reverse osmosis membrane surfaces: Mechanisms, impacts, and potential cures.
- Author
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Li, Hongbin, Guo, Yongqiang, Liu, Chao, Zhou, Yi, Lin, Xiaofeng, and Gao, Fei
- Subjects
- *
REVERSE osmosis , *MICROBIAL growth , *FOULING , *WATER purification , *SEWAGE , *SEWAGE purification - Abstract
Membrane technologies have been extensively used in municipal or industrial wastewater reuse, desalination, and other water treatment processes. However, the inevitable membrane biofouling issue still limits the application of PA RO membranes in practical production. In this paper, the various aspects of PA RO membrane biofouling were reviewed, and the related causes, theories, and mechanisms of membrane biofouling were discussed. The development and current trends of membrane cleaning and different RO pretreatment technologies were summarized, and the necessity of adopting membrane pretreatment technology was highlighted. Furthermore, progress in research of antifouling RO membrane surface construction was reviewed, and anti-biofouling modification strategies and mechanisms, and their relative characteristics, advantages, and disadvantages were compared. The final section of the review discussed the challenges, technical issues, and future research directions, and the emphasis was providing novel ideas for mitigating RO membrane biofouling. The purpose of this review is to afford up-to-date insights into the mitigation tactics and underlying mechanisms of membrane biofouling. Given that microbial fouling is a ubiquitous issue, it is of significant reference significance to clarify the mechanism, structure, strategy, and modification technology of RO membrane anti-biofouling for most membrane materials used in urban sewage treatment, industrial wastewater reuse, and desalination. [Display omitted] • Review covers current state-of-the-art of antibiofouling RO membranes for water treatment. • The mechanisms and mitigation strategies of PA RO membrane biofouling are described. • Comparison and evaluation of the application of different modifiers and methods in antibiofouling RO membranes. • The challenges, technical issues, and future research directions of antibiofouling RO membrane are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
42. UV pretreatment reduced biofouling of ultrafiltration and controlled opportunistic pathogens in secondary water supply systems.
- Author
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Wang, Haibo, Hu, Haotian, Chen, Susu, Schwarz, Cory, Yin, Hong, Hu, Chisheng, Li, Guiwei, Shi, Baoyou, and Huang, Jingang
- Subjects
- *
FOULING , *WATER supply , *ULTRAFILTRATION , *LEGIONELLA pneumophila , *PATHOGENIC microorganisms , *WATER disinfection - Abstract
Secondary water supply systems (SWSSs) with low residual chlorine may pose a risk to consumers due to the regrowth of some pathogenic microbes. This study investigated how UV pretreatment would affect biofouling of UF membrane when it was used to remove opportunistic pathogens (OPs) in SWSSs. Our results indicated that UV pretreatment inactivated OPs effectively through OH . and O 2 .−, when residual chlorine was present in water from SWSSs. After UV-UF treatment, Legionella spp., Legionella pneumophila , Mycobacterium spp., and Acanthameoba spp. were undetected in the water. After UV pretreatment, the extracellular polymeric substances (EPS) production and associated β-sheet in the protein of EPS were reduced due to the inhibition of related functional genes. Foulant analysis indicated that biofilms formed on the UF membrane after UV pretreatment had visible crevices and small pores, a lower bacterial volumetric fraction and lower roughness than the untreated UF membrane. This structure improved the UF flux and reduced the biofouling. The transmembrane pressure (TMP) of UF membrane gradually decreased from 74 KPa to 60 KPa after 70 days running. Therefore, UV pretreatment could be used to reduce the potential microbial risk of water from SWSSs, and mitigate biofouling of UF membranes. [Display omitted] • UV-UF treatment removed opportunistic pathogens in secondary water supply systems. • UV pretreatment reduced the biofouling and improved the flux of UF membrane. • UV pretreatment reduced functional potential genes related to EPS production. • Lower EPS production resulted in lighter biofouling of UV-UF membrane. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
43. A coupled molybdenum disulfide - copper modification of NF membrane for enhanced anti-bacterial performance.
- Author
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Liu, Junxia, Cao, Pei, Yu, Xuri, Li, Tian, Sun, Wen, Zhao, Yaxiang, Yu, Hongjian, Wang, Zhihong, Zeng, Jialuo, Dong, Bingzhi, Yang, Haiyan, and Yu, Shuili
- Subjects
- *
MOLYBDENUM disulfide , *COPPER , *POLYAMIDE membranes , *MOLYBDENUM sulfides , *WATER purification , *COPPER ions , *BACILLUS subtilis , *POLYAMIDES - Abstract
Biofouling is a bottleneck in restricting nanofiltration (NF) application for drinking water treatment. In current study, we reported a novel molybdenum disulfide (MoS 2) ‑ copper (Cu2+) modification of polyamide NF membrane for enhanced anti-bacterial performance. The incorporation of Cu2+ into the separation layer through interfacial polymerization was to enhance the anti-microbial ability, while the introduction of lamellar MoS 2 into the polyamide active layer was to stably immobilize copper, as well as to provide an interlayer nanochannels for water transport and also to enhance membrane hydrophilicity. The resultant membrane showed an excellent anti-bacterial ability, with 99.1% and 96.7% inactivation efficiencies of Escherichia coli and Bacillus subtilis , respectively, at MoS 2 - Cu molar ratio of 1:0.3. Compared to the control membrane, the obtained membrane exhibited a 44% increase of pure water flux. Membrane stability assessment indicated that > 93% of initial loaded Cu2+ and Mo4+ remained in the membrane matrix after a 5-d shaking test. Membrane characterization suggested that the MoS 2 - Cu complexes were uniformly dispersed into the membrane active layer, which led to an increased membrane roughness that was favorable for antibiofouling. Overall, the facile MoS 2 – Cu addition with intensified anti-biofouling ability created in this study provides a promising membrane modification approach for practical application. [Display omitted] • A novel MoS 2 -Copper modification of NF membrane was proposed. • Copper ion was utilized to enhance membrane anti-biofouling ability. • MoS 2 was to stably immobilize copper, intensify hydrophilicity and provide interlayer nanochannels. • The MoS 2 -Cu modified membrane exhibited an excellent anti-bacterial performance. • The modified NF membrane had a 44% increase of pure water flux. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
44. Biofouling initiation on a microfiltration membrane related to deposition and adhesion of bacteria from the perspective of interface interactions.
- Author
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Yang, Songwen, Song, Zi, Li, Pu, Sun, Feiyun, Zeng, Haojie, Dong, Wenyi, Feng, Xiaochi, and Ren, Nanqi
- Subjects
- *
BACTERIAL adhesion , *ADHESION , *FOULING , *CARBON content of water , *MICROFILTRATION , *POLYVINYLIDENE fluoride , *SERUM albumin - Abstract
Inhibition of bacteria deposition and adhesion is an effective strategy to control biofouling in membrane applications. In this study, the deposition and adhesion characteristics of individual bacteria (Pseudomonas aeruginosa) on a polyvinylidene fluoride microfiltration membrane were systematically investigated from the perspective of interface interactions. Preliminary results demonstrated that the deposition process was compatible with and dominated by the intermediate blocking model and cake filtration model However, the adhesion process analyzed by thermodynamic analysis revealed that bacteria should, in theory, not adhere to the virgin membrane, which was inconsistent with the experimental results. Further experiments and theoretical analysis suggested that organic matter in feed water, bovine serum albumin (BSA), or sodium alginate (SA) increased the adhesion capacity of the membrane by changing the properties of the membrane, and the thermodynamic relationship resulted in a reduction in the total interface interaction energy, Lewis acid–base component, and repulsive force. Therefore, biofouling can be controlled by reducing BSA-like or SA-like organics and inhibiting protein secretion by bacteria. This study furthers the understanding of the bacterial attachment process, and provides new insights into the adhesion mechanism from the perspective of interface interactions and thermodynamic analysis. [Display omitted] • Initial deposition was compatible with Intermediate blocking model. • The interfacial interaction energy determined the adhesion capacity of bacteria. • Protein-like substances increased the probability of bacterial adhesion. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
45. Designing a biocidal reverse osmosis membrane coating: Synthesis and biofouling properties.
- Author
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Hibbs, Michael R., McGrath, Lucas K., Kang, Seoktae, Adout, Atar, Altman, Susan J., Elimelech, Menachem, and Cornelius, Chris J.
- Subjects
- *
REVERSE osmosis in saline water conversion , *BIOCIDES , *FOULING , *CHEMICAL synthesis , *ANTIBACTERIAL agents , *COATING processes - Abstract
A biocidal coating was developed in order to reduce biofouling on a reverse osmosis (RO) membrane using a quaternary ammonium (QA) functionalized polymer. The synthesis of a series of polysulfone (PS) ionomers with QA groups is described, and a method for spraying these QA ionomers as an alcoholic solution, which dried into water insoluble coatings. Contact angle and streaming potential were used to analyze the coating's hydrophilicity and surface charge. Both PS-QA1 and the commercial RO membrane had an apparent contact angle of 68° that increased to 126° for PS-QA12 corresponding to alkyl chain length. A negatively charged particle-probe was used to measure coated and uncoated RO membrane interaction forces. Measured interaction forces correlated strongly with the length of alkyl chains or hydrophobicity of the coated surfaces. Uncoated RO membranes and ones coated with PS-QA were exposed to suspensions of Escherichia coli cells. All four PS-QA coatings showed significant biotoxicity and killed 100% of the E. coli cells, but uncoated RO membranes had metabolically active biofilms. However, coatings tested in a RO crossflow system showed a flux reduction that is attributed to mass transfer resistance due to excessively thick films. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
46. Marine bacterial transparent exopolymer particles (TEP) and TEP precursors: Characterization and RO fouling potential.
- Author
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Li, Sheng, Winters, Harvey, Jeong, Sanghyun, Emwas, Abdul-Hamid, Vigneswaran, Saravanamuthu, and Amy, Gary L.
- Subjects
- *
REVERSE osmosis , *MARINE bacteria , *POLYMERS , *CHEMICAL precursors , *FOULING , *ARTIFICIAL membranes - Abstract
This paper investigated the characteristics and membrane fouling potential of bacterial transparent exopolymer particles (TEP)/TEP precursors released from two marine bacteria, Pseudidiomarina homiensis ( P. homiensis ) and Pseudoalteromonas atlantica ( P. atlantica ), isolated from the Red Sea. Results showed that both bacteria grew at the similar rate, but the production of TEP/TEP precursors from P. atlantica was higher than that from P. homiensis . During the 168 h of incubation time, production rates of TEP/TEP precursors from P. atlantica and P. homiensis were 0.30 and 0.08 xanthan gum eq. mg/L-h, respectively. Isolated bacterial TEP precursors were mainly biopolymer, and P. atlantica produced a significantly higher concentration of biopolymer than that produced by P. homiensis . TEP/TEP precursors from both marine bacteria possessed protein-like material and were very similar in composition to previously reported foulants isolated from a fouled reverse osmosis (RO) membrane. Bacterial TEP/TEP precursors mostly consisted of aliphatic hydrocarbon from amino acids and amide group carbon of proteins (around 55%). Bacterial TEP precursors caused obvious fouling on RO membranes, which may create an ideal environment for bacteria attachment and promote to biofouling. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
47. Effect of operating conditions on biofouling in reverse osmosis membrane processes: Bacterial adhesion, biofilm formation, and permeate flux decrease.
- Author
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Saeki, Daisuke, Karkhanechi, Hamed, Matsuura, Hirotaka, and Matsuyama, Hideto
- Subjects
- *
FOULING , *REVERSE osmosis process (Sewage purification) , *ARTIFICIAL membranes , *BACTERIAL adhesins , *BIOFILMS , *PSEUDOMONAS putida - Abstract
We systematically evaluated the effects of operating conditions on biofouling behaviors in reverse osmosis (RO) membrane processes. The biofouling experiment was performed by filtrating nutrient-containing feed water with a cross-flow cylindrical membrane cell through a circular polyamide RO membrane with pre-adhered Pseudomonas putida . The trans-membrane pressure (TMP) and stirring rates in the cell were controlled as operating conditions. The stirring rates brought about shear force and thus corresponded to cross-flow velocities on the membrane surfaces in commercial operations. Permeate flux was monitored during the filtration, and bacterial adhesion to the membrane surfaces was observed using a confocal laser scanning microscope. An increase in TMP increased both the reduction rate of permeate flux and the volume of adhered bacteria, thus facilitating biofouling. Osmolarity calculation on the membrane surface suggested that TMP affected bacterial growth by concentration polarization (CP) of nutrients. Higher stirring rate prevented reduction of permeate flux and bacterial growth on membrane surfaces. The hydrodynamic shear force generated by stirring effectively detached the adhered bacteria, while CP of nutrients was not remarkably affected by the range of stirring rates used in this study. These results suggest that lower TMP and higher stirring rates prevent biofilm formation by decreasing CP and promoting bacterial detachment. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
48. Characterization of microbial communities in water and biofilms along a large scale SWRO desalination facility: Site-specific prerequisite for biofouling treatments.
- Author
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Levi, Adi, Bar-Zeev, Edo, Elifantz, Hila, Berman, Tom, and Berman-Frank, Ilana
- Subjects
- *
BIOFILMS , *REVERSE osmosis process (Sewage purification) , *SALINE water conversion , *FOULING , *ENERGY economics , *BIOTIC communities , *MICROBIAL population genetics - Abstract
Biofouling impacts seawater reverse osmosis (SWRO) desalination plants by hindering module performance, increasing energetic demands, and incurring further costs. Here we investigated the spatial–temporal dynamics of microbial communities along the feedwater, pretreatment, and reverse osmosis stages of a large-scale SWRO desalination facility. While the composition of water-based microbial communities varied seasonally, the composition of biofilm microbial communities clustered by locations. Proteobacteria dominated throughout the water and biofilm communities while other dominant phyla varied seasonally and spatially. The microbial community composition significantly differed along the pathway locations of feedwater, rapid sand filtration (RSF), cartridge filters (CF), and the reverse osmosis (RO) membranes. Biofilms on the RSF and CF were composed of more diverse microbial populations than RO biofilms as determined by the effective number of species. Biofilms that developed along the treatment pathway (CF) served as inocula enhancing biofouling downstream on the RO membranes. Subsequently, we believe that prior to the development of advanced antibiofouling treatments for the desalination industries, the site-specific microbial community of feedwater, pretreatment and RO biofouling should be characterized. Site specific identification of these communities will enable optimization of pretreatment and cleaning procedures and can ultimately reduce chemical usage and incurred costs. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
49. The anti-biofouling properties of thin-film composite nanofiltration membranes grafted with biogenic silver nanoparticles.
- Author
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Liu, Shasha, Fang, Fang, Wu, Junjie, and Zhang, Kaisong
- Subjects
- *
THIN films , *NANOFILTRATION , *ARTIFICIAL membranes , *SILVER nanoparticles , *FOULING - Abstract
Biofouling is still one of the most challenging issues of nanofiltration. One of the practical strategies to reduce biofouling is to develop novel anti-biofouling membranes. Herein, biogenic silver nanoparticles (BioAg 0 -6) with the averaged diameter of only 6 nm were firstly grafted on the surface of polyamide NF membrane. The effect of grafted BioAg 0 -6 on the performance of thin-film composite (TFC) NF membranes was systematically investigated with a comparison to the grafted chemical AgNPs. BioAg 0 -6 grafted membrane (TFC-S-BioAg) increased the hydrophilicity of the TFC membrane and water permeability, while maintaining the relatively high salt rejection. The result of silver leaching experiment indicated that the grafted BioAg 0 -6 had a better stability on the membranes, the ratio of remained silver in the TFC-S-BioAg membrane was 95%, after soaked in pure water for 50 days. After 4 month immersion, the rejection of TFC-S-BioAg membrane remained more than 90% of initial rejection. The results of disk diffusion test revealed that both of TFC-S-BioAg membrane and TFC-S-ChemAg membrane showed effective anti-bacterial ability to inhibit Pseudomonas aeruginosa and Escherichia coli growth, the TFC-S-BioAg membrane showed more excellent and longer lasting antibacterial property. Therefore, BioAg 0 -6 grafted TFC membranes could be potential as an effective strategy to decrease biofouling in nanofiltration process. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
50. Tributyl tetradecyl phosphonium chloride for biofouling control in reverse osmosis processes.
- Author
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Kim, Taek-Seung and Park, Hee-Deung
- Subjects
- *
PHOSPHONIUM compounds , *FOULING , *REVERSE osmosis , *BIOCIDES , *SCANNING electron microscopy , *HYPOCHLORITES - Abstract
Biofouling is a major operational problem in reverse osmosis (RO) processes. Recently, direct dosing of non-oxidizing biocides into RO vessels has been attempted to effectively alleviate biofouling. Tributyl tetradecyl phosphonium chloride (TTPC) is an efficient non-oxidizing biocide, but its application to RO processes has been rarely studied. This study aimed to evaluate the applicability of TTPC to RO processes. Scanning electron microscopy and Fourier transform infrared spectroscopy analyses confirmed that the RO membrane was resistant to morphological and chemical damage up to 100,000 mg/L TTPC. Rejection of TTPC determined by a dead-end filtration unit was greater than 99.58%. Furthermore, low concentrations of TTPC (20–40 mg/L) had antimicrobial and antibiofilm properties, as determined by minimum inhibitory concentration, minimum bactericidal concentration, and evaluation of static biofilm formation. TTPC also effectively removed biofilms that had already formed on RO membranes. Given these properties of TTPC, this study demonstrates the potential for TTPC as a biocide controlling biofouling in RO processes. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
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