Relating Organic Fouling of Reverse Osmosis Membranes to Intermolecular Adhesion Forces

Lee, Sangyoup; Elimelech, Menachem

doi:10.1021/es051825h

Cited by 420 publications

(244 citation statements)

References 33 publications

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“…For systems that experience regular dry out such as remote solar thermal desalination, significant sodium chloride is often left behind after evaporation [7], since it is present in such high levels in most waters. Finally, in seawater applications, the remains of algae often cause biological fouling, and in fact the polysaccharide alginate is often used to study algae fouling [14,15]. Alginate can form a gel layer on membrane surfaces that causes significant diffusion resistance [16].…”

Section: Scaling In Membrane Distillationmentioning

confidence: 99%

Combining air recharging and membrane superhydrophobicity for fouling prevention in membrane distillation

Warsinger

Servi

Belleghem

et al. 2016

Journal of Membrane Science

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In previous studies of the desalination technology membrane distillation (MD), superhydrophobicity of the membrane has been shown to dramatically decrease fouling in adverse conditions, but the mechanism for this is not well understood. Additionally, air layers present on submerged solid superhydrophobic surfaces have been shown to dramatically reduce biofouling, and air-bubbling has been used to reducing fouling in MD. The present work studies the effect of maintaining air layers on the membrane surface and superhydrophobicity as a new method for preventing fouling of MD membranes by salts, particulates, and organic particles. Superhydrophobic MD membranes were prepared using initiated chemical vapor deposition (iCVD) of perfluorodecyl acrylate (PFDA) on poly(vinyldene fluoride) PVDF membranes and used to study the effects of hydrophobicity on fouling. A static MD setup with evaporation through an MD membrane but no condensing of permeate was used to examine the effect of air exposure on fouling, by measuring the increase in weight of the membrane caused by scale deposition. Theory was derived for the reduction of fouling on superhydrophobic surfaces. Air layers may displace fouling gels, reduce the area of feed in contact with the membrane, reduce foulant adhesion, and enhance superhydrophobicity in a Cassie-Baxter state. The study shows that the presence of air on the membrane surface significantly reduces biological fouling, but in some cases had mildly exacerbating effects on fouling of salts, especially when the air was not saturated with water vapor. Air recharging combined with superhydrophobicity reduced fouling in several cases where hydrophobic membranes alone did little.Keywords: membrane distillation; superhydrophobic surface; air layer; nucleation; anti-fouling

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Section: Scaling In Membrane Distillationmentioning

confidence: 99%

Combining air recharging and membrane superhydrophobicity for fouling prevention in membrane distillation

Warsinger

Servi

Belleghem

et al. 2016

Journal of Membrane Science

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“…These studies have consistently indicated that adhesion of acidic polysaccharides and other organic macromolecules and colloids in the feed water is a major factor in conditioning membrane surfaces in the initial phase of fouling. Macromolecular and colloidal forms of polysaccharides and proteins have been identified as the most problematic foulants in many feed waters [7] and compounds such as alginate (an acid polysaccharide) have been used as model organic foulants in several of these studies [9,10]. We suggest that in the subsequent phases of aquatic biofouling on membranes and other surfaces, the relatively large particles (> 0.4 µm <100 µm) of TEP in the overlying water play a significant role.…”

Section: Tep and Biofilm Developmentmentioning

confidence: 98%

“…The physical and chemical processes involved in organic fouling of membranes have been studied in considerable detail [6][7][8][9][10]. These studies have consistently indicated that adhesion of acidic polysaccharides and other organic macromolecules and colloids in the feed water is a major factor in conditioning membrane surfaces in the initial phase of fouling.…”

Section: Tep and Biofilm Developmentmentioning

confidence: 99%

“…There is an extensive literature in the membrane/desalination field on fouling of membranes by biomacromolecules and biofilm formation and many studies in the last 5-10 years have elucidated the mechanisms of proliferation of exopolymeric substances (EPS) and biofilm formation [8][9][10][11][12]. These studies showed that within the first few minutes of contact between natural waters on different surfaces, an uncharacterized "molecular fouling" appeared that was hypothesized to play a crucial role in the initiation of biofilm development on those surfaces.…”

Section: Introductionmentioning

confidence: 99%

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Transparent exopolymer particles: Potential agents for organic fouling and biofilm formation in desalination and water treatment plants

Bar‐Zeev

Berman‐Frank

Liberman³

et al. 2009

Desalination and Water Treatment

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A B S T R A C TTransparent exopolymer particles (TEP) are ubiquitous in marine and freshwaters, and have been subject to intensive study by oceanographers and limnologists over the past 15 years. These microscopic organic particles (visualized by Alcian Blue staining for acid polysaccharides) may be considered a planktonic form of exopolymeric substances (EPS). Two aspects relating to the potential involvement of TEP as important agents in organic fouling and biofilm formation on membranes in desalination and wastewater treatment plants were investigated: the efficiency of pretreatment processes in decreasing the amounts of TEP reaching the RO membranes at the Adom desalination plant, Ashkelon; and the active involvement of TEP in the early stages of biofilm formation. This study revealed that although pretreatment at the desalination plant lowered the levels of water quality parameters such as chlorophyll and SDI by ~90% relative to input, TEP concentrations were only decreased by ~30% upstream of the RO membranes. To follow TEP in the early stages of biofilm formation, glass slides were suspended in seawater over several days. Slides were removed daily, stained with Alcian Blue (for TEP) and DAPI (for bacteria) and examined under the microscope with Nomarski light illumination and UV-epifluorescence. By 18 h, we observed many areas stained with Alcian Blue as well as some individual bacteria on the surface. The Alcian Blue stained areas were not due to EPS proliferated by bacteria attached to the surface but derived from TEP originally in the feed water. After 18 h, there were increasing areas stained with Alcian Blue and greater numbers of bacteria growing on stained and unstained areas of the substrate surface. Taken together, these results imply that TEP in source waters are indeed likely to be key players in the establishment and subsequent development of biofilm on membranes and that pretreatment technology does not effectively remove these particles from reaching membranes. Recognition of the importance of TEP in aquatic biofilm formation could lead to the use of TEP as an indicator of the efficacy of current pretreatment methods as well as to the development of improved techniques to remove these particles upstream of membranes in desalination and wastewater treatment plants.

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“…Force measurements were performed in 1 mM NaCl solution at a tip speed of 1 m/s. The force was normalized to the radius of the particle, R. For a given system, F/R should be a good indicator of the membrane fouling potential [Lee and Elimelech, 2006]. Bacterial cell attachment assay followed the modified method suggested by Campbell et al [1999].…”

Section: Characterization and Measurementsmentioning

confidence: 99%

Analysis of micromixers and biocidal coatings on water-treatment membranes to minimize biofouling.

Webb¹,

James

Hibbs³

et al. 2009

Self Cite

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Biofouling, the unwanted growth of biofilms on a surface, of water-treatment membranes negatively impacts in desalination and water treatment. With biofouling there is a decrease in permeate production, degradation of permeate water quality, and an increase in energy expenditure due to increased cross-flow pressure needed. To date, a universal successful and cost-effect method for controlling biofouling has not been implemented. The overall goal of the work described in this report was to use high-performance computing to direct polymer, material, and biological research to create the next generation of water-treatment membranes. Both physical (micromixers -UV-curable epoxy traces printed on the surface of a watertreatment membrane that promote chaotic mixing) and chemical (quaternary ammonium groups) modifications of the membranes for the purpose of increasing resistance to biofouling were evaluated. Creation of low-cost, efficient water-treatment membranes helps assure the availability of fresh water for human use, a growing need in both the U. S. and the world. 3 EXECUTIVE SUMMARYSection 1: Biofouling, the unwanted growth of biofilms on a surface, of water-treatment membranes has a negative economic impact in desalination and water treatment. With biofouling there is a decrease in permeate production and an increase in energy expenditure due to increased cross-flow pressure needed. Biofouling leads to increased cleaning expenditures, it accelerates the degradation of the membranes, and degrades the water quality of the permeate. To date, a universal successful and cost-effect method for controlling biofouling has not been implemented. The goal of this project is to use high-performance computing to direct polymer, material, and biological research to create the next generation of water-treatment membranes. Both physical (micromixers -UV-curable epoxy traces printed on the surface of a watertreatment membrane that promote chaotic mixing) and chemical (quaternary ammonium groups) modifications of the membranes for the purpose of increasing resistance to biofouling were evaluated.Section 2: Features (micromixers) that promote chaotic mixing were fabricated on reverseosmosis membrane surfaces and evaluated using computational models and laboratory experiments to determine their effectiveness in reducing biofouling. Computational fluid dynamics models of membrane feed channels were developed using different patterns of micromixers on the membrane surface. The shear-stress distribution along the membrane surface was simulated for steady flows along the different micromixer configurations. In addition, the hypothetical mass transfer of a tracer from the membrane surface was used as a metric to compare the amount of scouring and mixing in configurations with and without micromixers. Epoxy micromixers were printed directly onto membrane surfaces, and different patterns were evaluated experimentally. Fluorescence hyperspectral imaging results showed that regions of simulated high shear stress on the membrane co...

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Relating Organic Fouling of Reverse Osmosis Membranes to Intermolecular Adhesion Forces

Cited by 420 publications

References 33 publications

Combining air recharging and membrane superhydrophobicity for fouling prevention in membrane distillation

Combining air recharging and membrane superhydrophobicity for fouling prevention in membrane distillation

Transparent exopolymer particles: Potential agents for organic fouling and biofilm formation in desalination and water treatment plants

Analysis of micromixers and biocidal coatings on water-treatment membranes to minimize biofouling.

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