The Experts below are selected from a list of 341523 Experts worldwide ranked by ideXlab platform
Heng Liang - One of the best experts on this subject based on the ideXlab platform.
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effect of pre oxidation on low pressure Membrane lpm for water and wastewater treatment a review
Chemosphere, 2019Co-Authors: Gang Wen, Haiqing Chang, Senlin Shao, Tinglin Huang, Heng LiangAbstract:Low pressure Membrane (LPM) filtration is a promising technology for drinking water production, wastewater reclamation as well as pretreatment for seawater desalination. However, wider implementation of LPM is restricted by their inherent drawbacks, i.e., Membrane fouling and insufficient rejection for dissolved contaminants. Pretreatment of feed water is a major method to improve the performance of LPM, and pre-oxidation has gained extensive attention because it can significantly alter compositions and properties of feed water through chemical reactions. This paper attempts to systematically review efficiency and mechanisms of pre-oxidation in Membrane fouling control and permeate water quality improvement. On the basis of briefly discussing major foulants and fouling mechanisms of LPM, advantages and disadvantages of pre-oxidation in mitigating organic fouling, inorganic fouling and biofouling are discussed in detail. Impacts of pre-oxidation on removal of micropollutants, bulk organic matter and inorganic pollutants are summarized, and potential by-products of different oxidants are presented. As a prerequisite for the integration of chemical oxidation with LPM filtration, compatibility of Membrane with oxidants at low concentration and long exposure time are highlighted. Finally, the existing challenges and future research needs in practical application of chemical oxidation to improve performance of LPM are also discussed.
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ultra low pressure Membrane based bio purification process for decentralized drinking water supply improved permeability and removal performance
Chemosphere, 2018Co-Authors: Xiaobin Tang, Xiaoxiang Cheng, Xuewu Zhu, Binghan Xie, Yuanqing Guo, Jinlong Wang, An Ding, Heng LiangAbstract:Abstract Ultra-low pressure gravity-driven Membrane (GDM) filtration has been proposed as a cost-efficiency alternative for the decentralized drinking water supply in terms of its simple operation and low energy consumptions, whereas its undesirable removals of dissolved organic compounds (DOC) and relatively low flux impede its widespread application. In order to improve its filtration performance, filter media (granular activated carbon (GAC), zeolite and bio-ceramsite) was directly coated on the Membrane surface to engineer an integrated GDM system. The coating filter layer and bio-cake layer on the Membrane surface could engineer a highly porous “multifunctional double layer” structure, which facilitated improvements of stabilized flux by 30%–120% relative to GDM control. Besides, coating filter media to GDM can efficiently combine the complementary performance between filter coat and GDM filtration, and thus the removals of CODMn were improved to 21%, 30% and 70% in bio-ceramsite, zeolite and GAC coated systems. Furthermore, the integrated GDM systems conferred much higher potentials in resisting the shock load of contaminants (e.g. organics, ammonia, iron and manganese) compared to GDM control. In addition, a low-aeration cleaning in presence of filter media scouring could efficiently improve the flux recovery from 35% to 50–94%, while the Membrane integrity test indicated that such filter media scouring would not damage the Membrane surface. Overall, these findings can hopefully spark improvements of both permeability and permeate quality in GDM filtration and bring relevant benefits to the applications of GDM technologies for decentralized drinking water supply.
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reducing ultrafiltration Membrane fouling during potable water reuse using pre ozonation
Water Research, 2017Co-Authors: Hui Wang, Heng Liang, Shane A Snyder, Minkyu Park, Israel J LopezAbstract:Abstract Wastewater reclamation has increasingly become popular to secure potable water supply. Low-Pressure Membrane processes such as microfiltration (MF) and ultrafiltration (UF) play imperative roles as a barrier of macromolecules for such purpose, but are often limited by Membrane fouling. Effluent organic matter (EfOM), including biopolymers and particulates, in secondary wastewater effluents have been known to be major foulants in Low-Pressure Membrane processes. Hence, the primary aim of this study was to investigate the effects of pre-ozonation as a pre-treatment for UF on the Membrane fouling caused by EfOM in secondary wastewater effluents for hydrophilic regenerated cellulose (RC) and hydrophobic polyethersulfone (PES) UF Membranes. It was found that greater fouling reduction was achieved by pre-ozonation for the hydrophilic RC Membrane than the hydrophobic PES Membrane at increasing ozone doses. In addition, the physicochemical property changes of EfOM, including biopolymer fractions, by pre-ozonation were systemically investigated. The classical pore blocking model and the extended Derjaguin−Landau−Verwey−Overbeek (XDLVO) theories were employed to scrutinize the fouling alleviation mechanism by pre-ozonation. As a result, the overarching mechanisms of fouling reduction were attributed to the following key reasons: (1) Ozone degraded macromolecules such as biopolymers like proteins and polysaccharides into smaller fractions, thereby increasing free energy of cohesion of EfOM and rendering them more hydrophilic and stable; (2) pre-ozonation augmented the interfacial free energy of adhesion between foulants and the RC/PES Membranes, leading to the increase of repulsions and/or the decrease of attractions; and (3) pre-ozonation prolonged the transition from pore blocking to cake filtration that was a dominant fouling mechanism, thereby reducing fouling.
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hydraulic backwashing for low pressure Membranes in drinking water treatment a review
Journal of Membrane Science, 2017Co-Authors: Haiqing Chang, Baicang Liu, Heng Liang, Shane A SnyderAbstract:Conventional drinking water treatment processes have faced several obstacles that are severely affected by water pollution and shortage, which makes it difficult to produce potable water effectively. Low-Pressure Membrane filtration, which includes ultrafiltration (UF) and microfiltration (MF), is one of the most promising treatment technologies for improving water quality. Periodic hydraulic backwashing is a necessity for the routine operation of UF/MF Membranes, but only sparse data are available regarding the optimization of backwashing procedures, while more attention has been directed toward Membrane fouling and cleaning. In the current work, we critically review the backwashing parameters of UF/MF Membranes used in municipal water supplies. These parameters include pressure, flux, permeability (or resistance), mass balance, and Membrane characterization techniques. The factors affecting backwash performance, which include Membrane properties, feed water properties and operating conditions, are discussed in detail. The pretreatments of feed water, such as peroxidation, adsorption, coagulation and filtration influence the performance of UF/MF Membranes to varying extents. The impacts of the backwash interval, backwash duration, backwash strength, air-assisted backwashing, chemically enhanced backwashing, and backwash water quality on backwash performance are summarized to provide more comprehensive data, which can improve backwash performance in full-scale drinking water and water reuse treatment plants.
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impact of aeration shear stress on permeate flux and fouling layer properties in a low pressure Membrane bioreactor for the treatment of grey water
Journal of Membrane Science, 2016Co-Authors: Heng Liang, An Ding, Nicolas Derlon, Ilona Szivak, Eberhard Morgenroth, Wouter PronkAbstract:Abstract Two different aeration regimes were studied in a low pressure gravity driven Membrane bioreactor without any flushing or (back-) washing. In one reactor, the aeration was positioned below the Membrane module, thus exposing the Membranes to aeration shear stress. A second reactor was operated at low shear stress by placing the aerator in a different compartment. Flux stabilization at 2.0 L/(m 2 h) occurred in the reactor with low shear stress while no flux stabilization was observed in the reactor with aeration shear stress, resulting in a flux of 0.5 L/(m 2 h) after 120 days. The thickness of the bio-fouling layer in the reactor with aeration shear was smaller (129 vs. 344 µm), which implies that shear stress resulted in a thinner, denser and less permeable bio-fouling layer. The results can be explained by differences in (1) the morphology of the bio-fouling layer and (2) the EPS contents (proteins and polysaccharides) in the bio-fouling layer. The low-shear system provides a suitable solution for decentralized grey water treatment, or other conditions where maintenance and energy consumption should be minimized. Furthermore, the results can contribute to decrease the energy consumption in MBR systems.
Shane A Snyder - One of the best experts on this subject based on the ideXlab platform.
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reducing ultrafiltration Membrane fouling during potable water reuse using pre ozonation
Water Research, 2017Co-Authors: Hui Wang, Heng Liang, Shane A Snyder, Minkyu Park, Israel J LopezAbstract:Abstract Wastewater reclamation has increasingly become popular to secure potable water supply. Low-Pressure Membrane processes such as microfiltration (MF) and ultrafiltration (UF) play imperative roles as a barrier of macromolecules for such purpose, but are often limited by Membrane fouling. Effluent organic matter (EfOM), including biopolymers and particulates, in secondary wastewater effluents have been known to be major foulants in Low-Pressure Membrane processes. Hence, the primary aim of this study was to investigate the effects of pre-ozonation as a pre-treatment for UF on the Membrane fouling caused by EfOM in secondary wastewater effluents for hydrophilic regenerated cellulose (RC) and hydrophobic polyethersulfone (PES) UF Membranes. It was found that greater fouling reduction was achieved by pre-ozonation for the hydrophilic RC Membrane than the hydrophobic PES Membrane at increasing ozone doses. In addition, the physicochemical property changes of EfOM, including biopolymer fractions, by pre-ozonation were systemically investigated. The classical pore blocking model and the extended Derjaguin−Landau−Verwey−Overbeek (XDLVO) theories were employed to scrutinize the fouling alleviation mechanism by pre-ozonation. As a result, the overarching mechanisms of fouling reduction were attributed to the following key reasons: (1) Ozone degraded macromolecules such as biopolymers like proteins and polysaccharides into smaller fractions, thereby increasing free energy of cohesion of EfOM and rendering them more hydrophilic and stable; (2) pre-ozonation augmented the interfacial free energy of adhesion between foulants and the RC/PES Membranes, leading to the increase of repulsions and/or the decrease of attractions; and (3) pre-ozonation prolonged the transition from pore blocking to cake filtration that was a dominant fouling mechanism, thereby reducing fouling.
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hydraulic backwashing for low pressure Membranes in drinking water treatment a review
Journal of Membrane Science, 2017Co-Authors: Haiqing Chang, Baicang Liu, Heng Liang, Shane A SnyderAbstract:Conventional drinking water treatment processes have faced several obstacles that are severely affected by water pollution and shortage, which makes it difficult to produce potable water effectively. Low-Pressure Membrane filtration, which includes ultrafiltration (UF) and microfiltration (MF), is one of the most promising treatment technologies for improving water quality. Periodic hydraulic backwashing is a necessity for the routine operation of UF/MF Membranes, but only sparse data are available regarding the optimization of backwashing procedures, while more attention has been directed toward Membrane fouling and cleaning. In the current work, we critically review the backwashing parameters of UF/MF Membranes used in municipal water supplies. These parameters include pressure, flux, permeability (or resistance), mass balance, and Membrane characterization techniques. The factors affecting backwash performance, which include Membrane properties, feed water properties and operating conditions, are discussed in detail. The pretreatments of feed water, such as peroxidation, adsorption, coagulation and filtration influence the performance of UF/MF Membranes to varying extents. The impacts of the backwash interval, backwash duration, backwash strength, air-assisted backwashing, chemically enhanced backwashing, and backwash water quality on backwash performance are summarized to provide more comprehensive data, which can improve backwash performance in full-scale drinking water and water reuse treatment plants.
Jeanphilippe Croue - One of the best experts on this subject based on the ideXlab platform.
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impact of effluent organic matter on low pressure Membrane fouling in tertiary treatment
Water Research, 2013Co-Authors: C Ayache, Marc Pidou, Jeanphilippe Croue, Jerome Labanowski, Yvan Poussade, Annie Tazipain, Jurg Keller, W GernjakAbstract:This study aims at comparing Low-Pressure Membrane fouling obtained with two different secondary effluents at bench and pilot-scale based on the determination of two fouling indices: the total fouling index (TFI) and the hydraulically irreversible fouling index (HIFI). The main objective was to investigate if simpler and less costly bench-scale experimentation can substitute for pilot-scale trials when assessing the fouling potential of secondary effluent in large scale Membrane filtration plants producing recycled water. Absolute values for specific flux and total fouling index for the bench-scale system were higher than those determined from pilot-scale, nevertheless a statistically significant correlation (r(2) = 0.63, α = 0.1) was obtained for the total fouling index at both scales. On the contrary no such correlation was found for the hydraulically irreversible fouling index. Advanced water characterization tools such as excitation-emission matrix fluorescence spectroscopy (EEM) and liquid chromatography with organic carbon detection (LC-OCD) were used for the characterization of foulants. On the basis of statistical analysis, biopolymers and humic substances were found to be the major contribution to total fouling (r(2) = 0.95 and r(2) = 0.88, respectively). Adsorption of the low molecular weight neutral compounds to the Membrane was attributed to hydraulically irreversible fouling (r(2) = 0.67).
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low pressure Membrane mf uf fouling associated with allochthonous versus autochthonous natural organic matter
Water Research, 2006Co-Authors: Jeanphilippe CroueAbstract:Natural organic matter (NOM) isolates/fractions; organic colloids, and hydrophobic (HPO), transphilic (TPI), and hydrophilic (HPI) fractions; isolated from a natural surface water as an allochthonous source, and in the form of algal organic matter (AOM) derived from blue green algae as an autochthonous source, were investigated in Low-Pressure Membrane filtration. The most significant flux decline was caused by organic colloids, with an intermediate flux decline caused by AOM derived (isolated) from ground and sonicated blue green algae. 3D fluorescence excitation–emission matrix (EEM) analyses revealed that colloids and AOM contain protein-like substances, and FTIR analyses showed overlapping peaks associated with the peptide bonds in proteins and alcohols in polysaccharides originating from extra- and/or intra-cellular materials. HP-SEC results also support a high content of apparently macromolecular compounds in the colloid fraction. The presence of a divalent cation (Ca2+), hypothesized to enhance fouling by NOM acids by a reduction in molecular charge, showed little effect. Morphological analyses indicated that the surface topography of fouled UF Membranes was elevated, presumably due to deposition of NOM on the Membrane surface. The pores of MF Membranes were reduced, suggesting pore blockage and/or constriction by NOM aggregates.
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identification and understanding of fouling in low pressure Membrane mf uf filtration by natural organic matter nom
Water Research, 2004Co-Authors: Nohwa Lee, Jeanphilippe Croue, Gary Amy, Herve BuissonAbstract:An understanding of natural organic matter (NOM) as a Membrane foulant and the behavior of NOM components in Low-Pressure Membrane fouling are needed to provide a basis for appropriate selection and operation of Membrane technology for drinking water treatment. Fouling by NOM was investigated by employing several innovative chemical and morphological analyses. Source (feed) waters with a high hydrophilic (HPI) fraction content of NOM resulted in significant flux decline. Macromolecules of a relatively hydrophilic character (e.g. polysaccharides) were effectively rejected by Low-Pressure Membranes, suggesting that macromolecular compounds and/or colloidal organic matter in the hydrophilic NOM fraction may be a problematic foulant of Low-Pressure Membranes. Moreover, the significant organic fouling that is contributed by polysaccharides and/or proteins in macromolecular and/or colloidal forms depends on molecular shape (structure) as well as size (i.e. molecular weight). More significant flux decline was observed in microfiltration (MF) compared to ultrafiltration (UF) Membrane filtration. MF Membrane fouling may be caused by pore blockage associated with large (macromolecular) hydrophilic molecules and/or organic colloids. In the case of UF Membranes, the flux decline may be caused by sequential or simultaneous processes of surface (gel layer) coverage during filtration. Morphological analyses support the notion that Membrane roughness may be considered as a more important factor in Membrane fouling by controlling interaction between molecules and the Membrane surface, compared to the hydrophobic/hydrophilic character of Membranes. Membrane fouling mechanisms are not only a function of Membrane type (MF versus UF) but also depend on source (feed) water characteristics.
J L Harris - One of the best experts on this subject based on the ideXlab platform.
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low pressure Membrane filtration of secondary effluent in water reuse pre treatment for fouling reduction
Journal of Membrane Science, 2008Co-Authors: Thang Pha Nguye, Felicity Roddick, J L HarrisAbstract:Abstract Fouling in the Low-Pressure Membrane filtration of secondary effluent for water reuse can be severe due to the complex nature of the components in the water. Pre-filtration, coagulation and anion exchange resin were investigated as pre-treatments for reducing fouling of microfiltration (MF) and ultrafiltration (UF) Membranes in the treatment of activated sludge-lagoon effluent. The key fouling components were determined using several analytical techniques to detect differences in the organic components between the feed and permeate. Pre-filtration (1.5 μm) enhanced the permeate flux for MF by removing particulates, but had little effect for UF. Marked flux improvement was obtained by coagulation pre-treatment at 5 mg L −1 Al 3+ with internal Membrane fouling being substantially alleviated. Anion exchange resin removed >50% of effluent organic matter but did not improve the flux or reduce irreversible Membrane fouling. These results, together with detailed organic compositional analyses, showed that the very high-molecular weight organic materials (40–70 kDa) comprised of hydrophilic components such as soluble microbial products, and protein-like extracellular matter were the major cause of Membrane fouling.
Joseph G Jacangelo - One of the best experts on this subject based on the ideXlab platform.
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novel approach for the analysis of bench scale low pressure Membrane fouling in water treatment
Journal of Membrane Science, 2009Co-Authors: Haiou Huang, Thayer A Young, Joseph G JacangeloAbstract:The concept of the unified Membrane fouling index (UMFI) was introduced recently for assessing the fouling of low pressure Membranes (LPM) used in water treatment. The major advantages of the UMFI over most other fouling indices are the universality (independent of filtration scale or mode) and specificity (based on the actual Membrane of interest for full-scale application). This study applied the concept of the UMFI to the assessment of fouling results obtained in a bench-scale fouling study. This study was conducted with combinations of four commercially available LPMs and four natural waters (including secondary wastewater effluent) under systematically varied hydrodynamic conditions. It was found that, with the adoption of the UMFI, the fouling potential of different Membrane and water combinations can be presented in a unified, concise, and quantitative way, enabling quantitative and integrated assessment of the fouling data and their relationships with different potential fouling factors. Expansion of the UMFI concept to other studies is anticipated to assist in the integration of the vast amount of bench-scale fouling results obtained with different LPMs; this integration is crucial to the mechanistic understanding of LPM fouling.
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unified Membrane fouling index for low pressure Membrane filtration of natural waters principles and methodology
Environmental Science & Technology, 2008Co-Authors: Haiou Huang, Thayer A Young, Joseph G JacangeloAbstract:Membrane filtration is considered an important technology that can contribute to the sustainability of water supplies. However, its continued development necessitates the establishment of proper techniques for the assessment of Membrane fouling. Unified Membrane Fouling Index (UMFI) was developed in this study in order to quantify and assess the fouling of Low-Pressure Membranes (LPM) observed at various scales of water treatment. The foundation of UMFI is a revised Hermia model applied to both constant pressure and constant flux filtration. The adoption of UMFI makes it possible to simplify and standardize the bench-scale testing of Membrane fouling potential by directly using the commercial LPM of interest. This approach can overcome a major challenge to fouling assessment, i.e., the Membrane-specificity of fouling potential, which has not been wholly addressed by existing fouling indices. The fundamentals of UMFI are presented in this paper, together with the methodology for bench-scale testing. The ap...
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unified Membrane fouling index for low pressure Membrane filtration of natural waters principles and methodology
Environmental Science & Technology, 2008Co-Authors: Haiou Huang, Thayer A Young, Joseph G JacangeloAbstract:Membrane filtration is considered an important technology that can contribute to the sustainability of water supplies. However, its continued development necessitates the establishment of proper techniques for the assessment of Membrane fouling. Unified Membrane Fouling Index (UMFI) was developed in this study in order to quantify and assess the fouling of Low-Pressure Membranes (LPM) observed at various scales of water treatment. The foundation of UMFI is a revised Hermia model applied to both constant pressure and constant flux filtration. The adoption of UMFI makes it possible to simplify and standardize the bench-scale testing of Membrane fouling potential by directly using the commercial LPM of interest. This approach can overcome a major challenge to fouling assessment, i.e., the Membrane-specificity of fouling potential, which has not been wholly addressed by existing fouling indices. The fundamentals of UMFI are presented in this paper, together with the methodology for bench-scale testing. The application of UMFI to the assessment of the fouling of a LPM by a natural surface water is also discussed. Good agreement between bench-scale UMFI and pilot-scale UMFI was found, suggesting the validity of this new scientific concept for environmental applications.
