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Journal ArticleDOI: 10.1016/J.WATRES.2021.116995

Effect of ultraviolet disinfection on the fouling of reverse osmosis membranes for municipal wastewater reclamation.

02 Mar 2021-Water Research (Pergamon)-Vol. 195, pp 116995-116995
Abstract: Membrane fouling is a prominent problem that hinders the stable and efficient operation of the reverse osmosis (RO) system for wastewater reclamation. Previous studies showed that chlorine disinfection, which was commonly used in industrial RO systems as pretreatment, could lead to significant change in microbial community structure and resulted in serious biofouling. In order to prevent biofouling during wastewater reclamation, the effect of ultraviolet (UV) disinfection on RO membrane fouling was investigated and the mechanism was also revealed in this study. With the disinfection pretreatment by UV of 20, 40 and 80 mJ/cm2, the bacteria in the feed water were inactivated significantly with a log reduction of 1.11, 2.55 and 3.61-log, respectively. However, RO membrane fouling aggravated with higher UV dosage. Especially, in the group with the UV dosage of 80 mJ/cm2, the normalized RO membrane flux decreased by 15% compared with the control group after 19-day operation. The morphology of the fouled RO membranes indicated serious biofouling in all groups. The analysis on the microbial amount of the foulants showed that the heterotrophic plate counts (HPC) and ATP content on the fouled RO membranes with and without UV disinfection were at the same level. However, the total organic carbon content of the foulants with the UV dosage of 40 and 80 mJ/cm2 was significantly higher than the control group, with higher content of proteins and polysaccharides as indicated by EEM and FTIR spectrum. Microbial community structure analysis showed that some typical UV-resistant bacteria were selected and remained on the RO membrane after disinfection with high UV dosage, including. These residual bacteria after disinfection with high UV dosage showed higher extracellular polymeric substances (EPS) secretion compared with those without UV disinfection, and thus aggravated RO membrane fouling. Thicker EPS could decrease the transmission of UV rays, and thus bacteria with higher EPS secretion might be selected after UV disinfection.

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Topics: Membrane fouling (58%), Fouling (52%), Biofouling (50%)

7 results found

Journal ArticleDOI: 10.1021/ACS.LANGMUIR.1C01647
Lihua Chen1, Jing Wei1, Qi Tian1, Zhichao Han1  +3 moreInstitutions (1)
09 Aug 2021-Langmuir
Abstract: Desalination by solar steam generation (SSG) has emerged as one of the most efficient approaches to address the issue of global water shortage. In this work, novel graphene oxide (GO)-based solar steam generators (GO-SSGs) with aligned channels were prepared by directional freezing and simple carbonization of a hydrogel composed of GO and poly(vinyl alcohol) (PVA). Benefitting from their excellent light absorption (light absorption efficiency exceeds 94%), better thermal insulation (thermal conductivity, 0.259 W/(m K)), and suitable porous structure, which facilitates rapid water transportation, the GO-SSGs show superior SSG performance with a high solar energy conversion efficiency of up to 92% achieved under an irradiation of 1.0 kW/m2. Interestingly, uniquely aligned channels endow them with good salt-rejection performance; the solar energy conversion efficiency of GO-SSGs in 20 wt % NaCl, KCl, and MgCl2 brine can reach more than 85%. To improve their antifouling performance, a chemically hydrophilic and oleophobic modification was conducted, making it possible to run SSG even in oily wastewater; for instance, a solar energy conversion efficiency of 84% was obtained in an aqueous solution containing 10 wt % n-hexadecane. Compared with the existing photothermal materials, these materials show advantages of simple manufacture, high SSG efficiency, superior salt tolerance, and antifouling performance, which make them promising candidates as a kind of new high-performance photothermal materials for desalination even in oily wastewater, thus further expanding the scope of their practical SSG application.

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Topics: Water transport (52%), Desalination (51%)

Journal ArticleDOI: 10.1016/J.MEMSCI.2021.119850
Gen-Qiang Chen1, Yin-Hu Wu1, Pin-Sheng Fang1, Yuan Bai1  +9 moreInstitutions (2)
Abstract: Soluble microbial products (SMP) are one of the main causes of reverse osmosis (RO) membrane fouling in wastewater reclamation, and coagulation and adsorption are commonly used to prevent such fouling. However, the mechanism by which typical coagulants and adsorbents affect the RO membrane fouling caused by SMP remains unclear. In this study, two bacterial strains isolated from fouled RO membranes in a full-scale wastewater reclamation plant were used to produce SMP. Both bacterial strains were found to generate high SMP yield (0.23–0.25 g/g), which caused severe RO membrane fouling. Coagulation by polyaluminum chloride (PACl) and ferric chloride (FeCl3) and adsorption by granular activated carbon (GAC) were applied as pretreatment methods to alleviate the membrane fouling caused by SMP. Compared with PACl, FeCl3 performed better in removing SMP, decreasing fluorescence intensity, and reducing molecular weight (MW). GAC preferentially adsorbed protein and humic substances in SMP and unselectively and efficiently removed fluorescent compounds; however, it could only remove a limited amount of the high-MW compound. The RO membrane fouling potential of treated SMP was investigated, and FeCl3 and GAC were found to effectively alleviate the fouling. In addition to a decrease in the dissolved organic carbon content of SMP, a decrease in specific fluorescence intensity, MW, and polysaccharide content caused by coagulation or adsorption could result in lower RO membrane fouling.

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Topics: Membrane fouling (67%), Fouling (58%), Reverse osmosis (50%)

Open accessJournal ArticleDOI: 10.1016/J.JWPE.2021.102402
Abstract: Water treatment plants applied large amount of chlorine to eliminate microorganisms and prevent future microbial contamination of drinking water. Electrophilic substitution and electron transfer activities between natural organic matter (NOM) and free chlorine resulted in the formation of chlorinated disinfection byproducts (DBPs). Chlorinated DBPs' consumption and exposure provoked severe health risks susceptible to cause death and/or lifetime illness. Conventional water treatment approaches such as membrane filtration, adsorption, sedimentation, and coagulation are much appropriated to eliminate chlorinated DBPs' precursors with a percentage removal estimated at 70. At the lowest concentration of chlorinated DBPs, conventional water treatment approaches fail to eliminate chlorinated DBPs in drinking water. In this review, we discussed catalytic hydrodehalogenation as an efficient approach to advance a complete eradication of chlorinated DBPs in drinking water. Metal nanocatalysts contributions were reviewed to understand the chemical pathways throughout the catalytic hydrodehalogenation of chlorinated DBPs. Palladium received much attention as metal nanocatalysts to facilitate the catalytic hydrodehalogenation of chlorinated DBPs. Catalytic investigations through novel nanocatalysts exploration should be intensified to gain insights in catalytic hydrodehalogenation of chlorinated DBPs and advance its possible incorporation in water treatment technology.

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Topics: Water treatment (52%)

Journal ArticleDOI: 10.1016/J.MEMSCI.2021.120007
Gen-Qiang Chen1, Yin-Hu Wu1, Zhuo Chen1, Li-Wei Luo1  +8 moreInstitutions (2)
Abstract: Extracellular polymeric substances (EPS) were the main cause of membrane biofouling in advanced treatment of wastewater. Disinfection was usually used to reduce microbial concentration in the feed water and prevent biofouling. However, the disinfection residual bacteria (DRB) could regrow to produce EPS, and there was still a paucity of information on EPS productivity and properties from DRB and their further interaction with membranes. In this study, three commonly-used disinfection methods (free chlorine, chloramine and ozone disinfection) were used to investigate their effects on microbial EPS production and the further effects on membrane fouling. It was found all the disinfection treatment increased the relative abundance of typical bacterial genus with high EPS production ability, and thus significantly enhanced EPS volumetric productivity (by 26%–82%). The molecular weight and fluorescence intensity of EPS produced by DRB also increased. The fouling potential of these EPS on ultrafiltration (UF) membranes and reverse osmosis (RO) membranes was then tested. EPS of DRB showed significantly higher fouling potential. Compared with the control group, the time for transmembrane pressure (TMP) increased to 3 bar decreased by 43%–49% in the constant-flow UF system in the disinfection groups. As for the constant-pressure RO systems, the final flux decreased by 33%–41% in the disinfection groups compared with the control group. The thickness of foulants on UF and RO membranes in the disinfection groups was all higher than that in the control group. The extended Derjaguin–Landau–Verwey–Overbeek (XDLVO) theory further showed that the EPS of DRB had significantly higher interaction energy with membranes than that in the control group. Therefore, caution should be exercised when oxidizing disinfection was used as pre-treatment for membrane filtration in the wastewater reclamation process.

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Topics: Membrane fouling (56%), Ultrafiltration (51%), Fouling (51%)


38 results found

Journal ArticleDOI: 10.1038/NPROT.2015.024
Huayan Yang1, Shouning Yang1, Jilie Kong1, Aichun Dong2  +1 moreInstitutions (2)
01 Mar 2015-Nature Protocols
Abstract: Fourier transform IR (FTIR) spectroscopy is a nondestructive technique for structural characterization of proteins and polypeptides. The IR spectral data of polymers are usually interpreted in terms of the vibrations of a structural repeat. The repeat units in proteins give rise to nine characteristic IR absorption bands (amides A, B and I-VII). Amide I bands (1,700-1,600 cm(-1)) are the most prominent and sensitive vibrational bands of the protein backbone, and they relate to protein secondary structural components. In this protocol, we have detailed the principles that underlie the determination of protein secondary structure by FTIR spectroscopy, as well as the basic steps involved in protein sample preparation, instrument operation, FTIR spectra collection and spectra analysis in order to estimate protein secondary-structural components in aqueous (both H2O and deuterium oxide (D2O)) solution using algorithms, such as second-derivative, deconvolution and curve fitting. Small amounts of high-purity (>95%) proteins at high concentrations (>3 mg ml(-1)) are needed in this protocol; typically, the procedure can be completed in 1-2 d.

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509 Citations

Journal ArticleDOI: 10.1016/J.DESAL.2011.06.063
17 Oct 2011-Desalination
Abstract: Reverse osmosis membranes are becoming increasingly popular for water purification applications that require high salt rejection such as brackish and seawater desalination. However, due to fouling by microorganisms, they have been unable to realize their full potential as of yet. Biofouling leads to the use of higher operating pressure, more frequent chemical cleaning, and shorter membrane life. This paper reviews the causes, consequences and control of biofouling in RO membranes used for seawater desalination. After a brief introduction, the fundamentals of biofouling are discussed in some detail: biofilm formation, role of EPS, and sequence of events leading to biofouling. This is followed by a section on consequences of biofouling on membrane processes with particular emphasis on water permeability and salt rejection. The mechanisms of performance degradation are discussed in some detail for both of these parameters. The last section of this paper reviews the different antifouling strategies that have recently gained more attention with special emphasis on membrane surface modification. A brief conclusion with some recommendations and suggestions is presented at the end of the article.

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Topics: Desalination (58%), Reverse osmosis (54%), Biofouling (53%) ... read more

468 Citations

Journal ArticleDOI: 10.1016/J.WATRES.2009.02.026
Zhiwei Wang1, Zhichao Wu1, Shujuan Tang1Institutions (1)
01 May 2009-Water Research
Abstract: A pilot-scale submerged membrane bioreactor (MBR) for real municipal wastewater treatment was operated for over one year in order to investigate extracellular polymeric substances (EPS) properties and their role in membrane fouling. The components and properties of bound EPS were examined by the evaluation of mean oxidation state (MOS) of organic carbons, Fourier transform infrared (FT-IR) spectroscopy, three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy, and gel filtration chromatography (GFC), etc. Test results showed that MOS of organic carbons in the bound EPS was ranging from -0.14 to -0.51, and major components could be assessed as proteins and carbohydrates. FT-IR analysis confirmed the presence of proteins and carbohydrates in the bound EPS. The organic substances with fluorescence characteristics in the bound EPS were identified as proteins, visible humic acid-like substances and fulvic acid-like substances by EEM technology. GFC analysis demonstrated that EPS had part of higher MW molecules and a broader MW distribution than the influent wastewater. It was also found that a high shear stress imposed on mixed liquor could result in the release of EPS, which would in turn influence membrane fouling in MBRs. Bound EPS solution was observed to have a stronger potential of fouling than mixed liquor. During long-term operation of the MBR, bound EPS demonstrated positive correlations with membrane fouling while temperature was verified as a negative factor affecting EPS concentration. Compared to tightly bound EPS (TB-EPS), loosely bound EPS (LB-EPS) showed more significant correlations with membrane fouling. This critical investigation would contribute towards a better understanding of the behavior, composition and fouling potential of EPS in MBR operation.

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Topics: Membrane fouling (63%), Membrane bioreactor (52%), Fouling (52%) ... read more

449 Citations

Open accessJournal ArticleDOI: 10.1016/J.SCITOTENV.2017.03.235
Abstract: Reverse osmosis (RO) membrane technology is one of the most important technologies for water treatment. However, membrane fouling is an inevitable issue. Membrane fouling leads to higher operating pressure, flux decline, frequent chemical cleaning and shorter membrane life. This paper reviews membrane fouling types and fouling control strategies, with a focus on the latest developments. The fundamentals of fouling are discussed in detail, including biofouling, organic fouling, inorganic scaling and colloidal fouling. Furthermore, fouling mitigation technologies are also discussed comprehensively. Pretreatment is widely used in practice to reduce the burden for the following RO operation while real time monitoring of RO has the advantage and potential of providing support for effective and efficient cleaning. Surface modification could slow down membrane fouling by changing surface properties such as surface smoothness and hydrophilicity, while novel membrane materials and synthesis processes build a promising future for the next generation of RO membranes with big advancements in fouling resistance. Especially in this review paper, statistical analysis is conducted where appropriate to reveal the research interests in RO fouling and control.

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Topics: Membrane fouling (75%), Fouling mitigation (72%), Fouling (64%) ... read more

353 Citations

Journal ArticleDOI: 10.1021/ES900087J
Abstract: This study elucidates the mechanisms by which extracellular polymeric substances (EPS) impact permeate water flux and salt rejection during biofouling of reverse osmosis (RO) membranes. RO fouling experiments were conducted with Pseudomonas aeruginosa PAO1, EPS extracted from PAO1 biofilms, and dead PAO1 cells fixed in formaldehyde. While a biofouling layer of dead bacterial cells decreases salt rejection and permeate flux by a biofilm-enhanced osmotic pressure mechanism, the EPS biofouling layer adversely impacts permeate flux by increasing the hydraulic resistance to permeate flow. During controlled fouling experiments with extracted EPS in a simulated wastewater solution, polysaccharides adsorbed on the RO membranes much more effectively than proteins (adsorption efficiencies of 61.2-88.7% and 11.6-12.4% for polysaccharides and proteins, respectively). Controlled fouling experiments with EPS in sodium chloride solutions supplemented with 0.5 mM calcium ions (total ionic strength of 15 mM) indicate that calcium increases the adsorption efficiency of polysaccharides and DNA by 2- and 3-fold, respectively. The increased adsorption of EPS onto the membrane resulted in a significant decrease in permeate water flux. Corroborating with these calcium effects, atomic force microscopy (AFM) measurements demonstrated that addition of calcium ions to the feed solution results in a marked increase in the adhesion forces between a carboxylated particle probe and the EPS layer. The increase in the interfacial adhesion forces is attributed to specific EPS-calcium interactions that play a major role in biofouling of RO membranes.

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Topics: Membrane technology (55%), Membrane (55%), Biofouling (55%) ... read more

316 Citations