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Menachem Elimelech - One of the best experts on this subject based on the ideXlab platform.

  • organic Fouling Behavior of superhydrophilic polyvinylidene fluoride pvdf ultrafiltration membranes functionalized with surface tailored nanoparticles implications for organic Fouling in membrane bioreactors
    Journal of Membrane Science, 2014
    Co-Authors: Shuai Liang, Xia Huang, Genggeng Qi, Kang Xiao, Emmanuel P Giannelis, Menachem Elimelech
    Abstract:

    Abstract This study systematically investigates the organic Fouling Behavior of a superhydrophilic polyvinylidene fluoride (PVDF) ultrafiltration membrane functionalized via post-fabrication tethering of surface-tailored silica nanoparticles to poly(methacrylic acid)-grafted PVDF membrane surface. Sodium alginate (SA), Suwannee River natural organic matter (SRNOM), and bovine serum albumin (BSA) were used as model organic foulants to investigate the antiFouling Behavior of the superhydrophilic membrane with combined-Fouling (mixture of foulants) and individual-Fouling (single foulant) tests. A membrane bioreactor (MBR) plant supernatant was also used to verify the organic antiFouling property of the superhydrophilic membrane under realistic conditions. Foulant size distributions and foulant–membrane interfacial forces were measured to interpret the observed membrane Fouling Behavior. Molecular weight cutoff measurements confirmed that membrane functionalization did not adversely affect the intrinsic membrane selectivity. Both filtration tests with the synthetic foulant-mixture solution (containing SA, SRNOM, and BSA) and MBR plant supernatant demonstrated the reliability and durability of the antiFouling property of the superhydrophilic membrane. The conspicuous reduction in foulant–membrane interfacial forces for the functionalized membrane further verified the antiFouling properties of the superhydrophilic membrane, suggesting great potential for applications in wastewater treatment.

  • superhydrophilic thin film composite forward osmosis membranes for organic Fouling control Fouling Behavior and antiFouling mechanisms
    Environmental Science & Technology, 2012
    Co-Authors: Alberto Tiraferri, Emmanuel P Giannelis, Yan Kang, Menachem Elimelech
    Abstract:

    This study investigates the Fouling Behavior and Fouling resistance of superhydrophilic thin-film composite forward osmosis membranes functionalized with surface-tailored nanoparticles. Fouling experiments in both forward osmosis and reverse osmosis modes are performed with three model organic foulants: alginate, bovine serum albumin, and Suwannee river natural organic matter. A solution comprising monovalent and divalent salts is employed to simulate the solution chemistry of typical wastewater effluents. Reduced Fouling is consistently observed for the superhydrophilic membranes compared to control thin-film composite polyamide membranes, in both reverse and forward osmosis modes. The Fouling resistance and cleaning efficiency of the functionalized membranes is particularly outstanding in forward osmosis mode where the driving force for water flux is an osmotic pressure difference. To understand the mechanism of Fouling, the intermolecular interactions between the foulants and the membrane surface are a...

  • comparison of Fouling Behavior in forward osmosis fo and reverse osmosis ro
    Journal of Membrane Science, 2010
    Co-Authors: Menachem Elimelech, Seungkwan Hong
    Abstract:

    Abstract Fouling Behaviors during forward osmosis (FO) and reverse osmosis (RO) are compared. Alginate, humic acid, and bovine serum albumin (BSA) are used as model organic foulants, and two suspensions of silica colloids of different sizes are chosen as model particulate foulants. To allow meaningful comparison of Fouling Behavior, identical hydrodynamic operating conditions (i.e., initial permeate flux and cross-flow velocity) and feed water chemistries (i.e., pH, ionic strength, and calcium concentration) are employed during FO and RO Fouling runs. The observed flux-decline Behavior in FO changed dramatically with the type of organic foulant, size of colloidal foulant, and the type of the draw solution employed to generate the osmotic driving force. Based on these experimental data and the systematic comparisons of Fouling Behaviors of FO and RO, we provide new insights into the mechanisms governing FO Fouling. In FO, reverse diffusion of salt from the draw solution to the feed side exacerbates the cake-enhanced osmotic pressure within the Fouling layer. The elevated osmotic pressure near the membrane surface on the feed side leads to a substantial drop in the net osmotic driving force and, thus, significant decline of permeate flux. Our results further suggest that the structure (i.e., thickness and compactness) of the Fouling layers of FO and RO is quite different. By varying the cross-flow velocity during the organic Fouling runs, we were able to examine the Fouling reversibility in FO and RO. The permeate flux during organic Fouling in FO recovered almost completely with increasing cross-flow velocity, while no noticeable change was observed for the RO system. Our results suggest that organic Fouling in FO could be controlled effectively by optimizing the hydrodynamics in the feed stream without employing chemical cleaning.

  • Fatty acid Fouling of reverse osmosis membranes: Implications for wastewater reclamation
    Water Research, 2008
    Co-Authors: Menachem Elimelech
    Abstract:

    Abstract Effluent organic matter (EfOM) contributes significantly to organic Fouling of reverse osmosis (RO) membranes in advanced wastewater reclamation. In this study, the effect of feed solution chemistry (solution pH and Ca 2+ concentration) on the Fouling of RO membranes by octanoic acid—selected to represent fatty acids in EfOM—is investigated. Crossflow Fouling experiments demonstrate that RO membrane Fouling is much more significant at solution pH below the p K a of the octanoic acid (p K a  = 4.9) than at an elevated pH. Octanoic acid permeates across the membranes more readily at solution pH below its p K a than at elevated pH. At pH below the octanoic acid p K a , Fouling Behavior is not affected by calcium ions, whereas at elevated pH, the rate of flux decline decreases with higher calcium ion concentration. The effect of calcium on the Fouling Behavior was further verified from foulant–foulant adhesion forces, determined by atomic force microscopy (AFM) force measurements under solution chemistries identical to those of the crossflow Fouling experiments. To investigate the implications of octanoic acid Fouling for wastewater reclamation, the effect of octanoic acid on membrane Fouling by a combination of organic foulants in the presence of calcium ions is studied. At a solution chemistry simulating that of typical wastewater effluents, the addition of octanoic acid to a feed solution containing alginate, bovine serum albumin, and Suwannee River natural organic matter, does not enhance membrane Fouling Behavior. This observation could be attributed to the significant contribution of the alginate–calcium complexes within the Fouling layer to the total membrane resistance.

  • Role of membrane surface morphology in colloidal Fouling of cellulose acetate and composite aromatic polyamide reverse osmosis membranes
    Journal of Membrane Science, 1997
    Co-Authors: Menachem Elimelech, Amy E. Childress, Xiaohua Zhu, Seungkwan Hong
    Abstract:

    Laboratory-scale colloidal Fouling tests, comparing the Fouling Behavior of cellulose acetate and aromatic polyamide thin-film composite reverse osmosis (RO) membranes, are reported. Fouling of both membranes was studied at identical initial permeation rates so that the effect of the transverse hydrodnamic force (permeation drag) on the Fouling of both membranes is comparable. Results showed a significantly higher Fouling rate for the thin-film composite membranes compared to that for the cellulose acetate membranes. Addition of an anionic surfactant (sodium dodecyl sulfate, SDS) to mask variations in chemical and electrokinetic surface characteristics of the cellulose acetate and aromatic polyamide membranes resulted in only a small change in the Fouling Behavior. The higher Fouling rate for the thin-film composite membranes is attributed to surface roughness which is inherent in interfacially polymerized aromatic polyamide composite membranes. AFM and SEM images of the two membrane surfaces strongly support this conclusion. These surface images reveal that the thin-film composite membrane exhibits large-scale surface toughness of ridge-and-valley structure, while the cellulose acetate membrane surface is relatively smooth.

Mikko Hupa - One of the best experts on this subject based on the ideXlab platform.

  • the Fouling Behavior of rice husk ash in fluidized bed combustion 1 fuel characteristics
    Energy & Fuels, 2005
    Co-Authors: Bengtjohan Skrifvars, Patrik Yrjas, Jouni Kinni, Peter Siefen, Mikko Hupa
    Abstract:

    Rice husk can be considered as an “opportunity fuel” for energy production. However, although rice husk has long been identified as a source for energy production, only limited experience exists from rice husk firing in larger-scale combustors. Only a few units worldwide are reported to be using rice husk as their main fuel. One concern in rice husk firing is the Behavior of the ash, i.e., its slagging and Fouling tendency, as well as its abrasiveness. This paper presents the very characteristic properties of the rice husk ash, as measured by a variety of laboratory tests and analyses, and compares these characteristics with eucalyptus bark and rice straw, as well as with some other biomass fuels. The paper is the first in a series of two, where we report from a recently finished study on the slagging and Fouling Behavior of rice husk when fired alone or in combination with other fuels in a fluidized-bed boiler. In the second part of the series, we will report the results of fireside Fouling measurements ...

  • the Fouling Behavior of rice husk ash in fluidized bed combustion 2 pilot scale and full scale measurements
    Energy & Fuels, 2005
    Co-Authors: Bengtjohan Skrifvars, Patrik Yrjas, Jouni Kinni, Tor Lauren, Honghi Tran, Mikko Hupa
    Abstract:

    This paper is the second in a series of two on the slagging and Fouling Behavior of rice husk when fired alone or in combination with other fuels in a fluidized-bed boiler. The first paper involved the fuel properties of rice husk, as investigated by a variety of laboratory methods. In this second paper, we report the results of fireside Fouling measurements when burning rice husk alone and together with eucalyptus bark in various ratios. This study is based on short-term (3−10 h) deposit samples taken with air-cooled deposit probes in the superheater region of a large-scale (157 MWth) bubbling fluidized-bed (BFB) boiler burning rice husk and eucalyptus bark. Using an entrained-flow type of pilot furnace, we further made more, systematic measurements of the influence of the fuel mixture ratio on the Fouling tendency of the fly ash formed. Burning of rice husk alone did not result in any detectable Fouling, neither in the pilot furnace nor on the deposit probes in the superheater area of the fluidized-bed ...

Xin Li - One of the best experts on this subject based on the ideXlab platform.

  • Fouling Behavior of isolated dissolved organic fractions from seawater in reverse osmosis ro desalination process
    Water Research, 2019
    Co-Authors: Xin Li, Stanislaus Raditya Suwarno, Emile Cornelissen, Tzyy Haur Chong
    Abstract:

    Abstract Organic Fouling is still elusive in seawater reverse osmosis (SWRO) desalination process. Classifying organics in seawater will provide an in-depth understanding of the important fraction on RO Fouling. In this study, dissolved organic matter (DOM) in seawater was fractionated and concentrated by membrane technique into three major fractions (i.e., biopolymer fraction, humic substance with building block fraction, and low molecular weight fraction) by their molecular weight (MW) according to the definitions in liquid chromatography with organic carbon detection (LC-OCD) method. Overall recovery of >80% was attained. The isolated organic fractions were compared with common model foulants such as sodium alginate (SA), bovine serum albumin (BSA), and humic acid (HA), in terms of chemical analyses using fluorescence-excitation emission matrix (FEEM) and LC-OCD, as well as their Fouling potentials. SWRO Fouling experiments were carried out and Fouling mechanism was investigated by atomic force microscopy (AFM) method and extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. Results showed that initial Fouling (i.e., foulant-membrane interaction) was the main driver in SWRO organic Fouling with biopolymer fraction as the major contributor followed by low molecular weight fraction. In addition, divalent ions was found to enhance the RO Fouling by increasing the adhesion and cohesion forces between foulant-membrane and foulant-foulant.

  • Fouling Behavior of polyethersulfone ultrafiltration membranes functionalized with sol gel formed zno nanoparticles
    RSC Advances, 2015
    Co-Authors: Xin Li, Jiansheng Li, Bart Van Der Bruggen, Jinyou Shen, Lianjun Wang
    Abstract:

    Ultrafiltration (UF) is an emerging membrane-based water separation process with potential application in drinking water treatment and for wastewater reuse. Nevertheless, membrane Fouling decreases membrane performance and increases the frequency and cost of chemical cleaning. In this work, we present a method for loading ZnO nanoparticles into a polyethersulfone (PES) UF membrane to improve its Fouling resistance. ZnO nanoparticles were synthesized with a sol–gel process using cost-effective precursors, resulting in particles with an average radius of 10 nm and ZnO content between 0.25 and 0.75 wt%. The hydrophilicity of the membrane surface was improved by the integration of ZnO nanoparticles, leading to a reduction in membrane contact angle (75.5 to 62.6°) and an increase in permeability (46.4 to 365.8 L m−2 h−1). Sodium alginate (SA), bovine serum albumin (BSA) and humic acid (HA) were chosen as model organic foulants to investigate Fouling Behavior of the fabricated membranes. Reduced Fouling was conspicuously observed for ZnO/PES composite membranes compared to control membranes in all Fouling cases. In order to better understand the Fouling mechanism, atomic force microscopy (AFM) was used to quantify the intermolecular adhesion forces between the foulant and the clean or fouled membrane. Lower adhesion forces were observed for the modified membranes, indicating that the addition of sol–gel formed ZnO nanoparticles endows the PES UF membrane with an improved antiFouling performance.

  • Fouling Behavior of polyethersulfone ultrafiltration membranes functionalized with sol–gel formed ZnO nanoparticles
    RSC Advances, 2015
    Co-Authors: Xin Li, Jiansheng Li, Bart Van Der Bruggen, Jinyou Shen, Lianjun Wang
    Abstract:

    Ultrafiltration (UF) is an emerging membrane-based water separation process with potential application in drinking water treatment and for wastewater reuse. Nevertheless, membrane Fouling decreases membrane performance and increases the frequency and cost of chemical cleaning. In this work, we present a method for loading ZnO nanoparticles into a polyethersulfone (PES) UF membrane to improve its Fouling resistance. ZnO nanoparticles were synthesized with a sol–gel process using cost-effective precursors, resulting in particles with an average radius of 10 nm and ZnO content between 0.25 and 0.75 wt%. The hydrophilicity of the membrane surface was improved by the integration of ZnO nanoparticles, leading to a reduction in membrane contact angle (75.5 to 62.6°) and an increase in permeability (46.4 to 365.8 L m−2 h−1). Sodium alginate (SA), bovine serum albumin (BSA) and humic acid (HA) were chosen as model organic foulants to investigate Fouling Behavior of the fabricated membranes. Reduced Fouling was conspicuously observed for ZnO/PES composite membranes compared to control membranes in all Fouling cases. In order to better understand the Fouling mechanism, atomic force microscopy (AFM) was used to quantify the intermolecular adhesion forces between the foulant and the clean or fouled membrane. Lower adhesion forces were observed for the modified membranes, indicating that the addition of sol–gel formed ZnO nanoparticles endows the PES UF membrane with an improved antiFouling performance.

Mathias Ulbricht - One of the best experts on this subject based on the ideXlab platform.

  • ultrafiltration of humic acid solutions through unmodified and surface functionalized low Fouling polyethersulfone membranes effects of feed properties molecular weight cut off and membrane chemistry on Fouling Behavior and cleanability
    Separation and Purification Technology, 2011
    Co-Authors: Polina Dobromirova Peeva, Aisyah Endah Palupi, Mathias Ulbricht
    Abstract:

    Abstract In the present work, polyethersulfone (PES) ultrafiltration (UF) membranes with molecular weight cut-off (MWCO) from 5 to 300 kDa were analyzed with respect to Fouling during filtration of humic acid (HA) model solution. The impact of MWCO and prefiltration of the feed solution on the Fouling Behavior of these membranes is presented. Moreover, an UV-initiated graft copolymerization of poly(ethylene glycol) methacrylate (PEGMA) onto PES membranes was performed and the effect of the applied modification was examined in terms of MWCO and water permeability changes as well as performance during filtration of HA. Moreover, the Fouling Behavior and principles during the filtration were compared. Membranes with higher MWCO exhibited stronger flux decline during UF but better cleanability. Prefiltration through 0.45 μm filter improved the membrane performance during filtration of HA but the efficiency of physical cleaning was deteriorated. The applied modification improved the membrane performance during ultrafiltration and facilitated the physical cleaning. This work contributes to a better understanding of the relationships between membrane MWCO, solute size and size distribution, membrane surface chemistry and membrane Fouling.

  • Ultrafiltration of humic acid solutions through unmodified and surface functionalized low-Fouling polyethersulfone membranes – Effects of feed properties, molecular weight cut-off and membrane chemistry on Fouling Behavior and cleanability
    Separation and Purification Technology, 2011
    Co-Authors: Polina Dobromirova Peeva, Aisyah Endah Palupi, Mathias Ulbricht
    Abstract:

    Abstract In the present work, polyethersulfone (PES) ultrafiltration (UF) membranes with molecular weight cut-off (MWCO) from 5 to 300 kDa were analyzed with respect to Fouling during filtration of humic acid (HA) model solution. The impact of MWCO and prefiltration of the feed solution on the Fouling Behavior of these membranes is presented. Moreover, an UV-initiated graft copolymerization of poly(ethylene glycol) methacrylate (PEGMA) onto PES membranes was performed and the effect of the applied modification was examined in terms of MWCO and water permeability changes as well as performance during filtration of HA. Moreover, the Fouling Behavior and principles during the filtration were compared. Membranes with higher MWCO exhibited stronger flux decline during UF but better cleanability. Prefiltration through 0.45 μm filter improved the membrane performance during filtration of HA but the efficiency of physical cleaning was deteriorated. The applied modification improved the membrane performance during ultrafiltration and facilitated the physical cleaning. This work contributes to a better understanding of the relationships between membrane MWCO, solute size and size distribution, membrane surface chemistry and membrane Fouling.

  • Fouling Behavior of aqueous solutions of polyphenolic compounds during ultrafiltration
    Journal of Food Engineering, 2009
    Co-Authors: Heru Susanto, Yu Feng, Mathias Ulbricht
    Abstract:

    Abstract This paper presents the first part of our study on ultrafiltration (UF) of polyphenolic compounds which is relevant to many industrial food and beverage feed streams. Two commercial polyethersulfone (PES) membranes with different cut-off (10 and 100 kg/mol) and one stabilized cellulose (cellulosic) membrane (10 kg/mol) were used. Membrane–solute interactions (adsorptive Fouling) and membrane–solute–solute interactions (UF Fouling) as well as the effects of pH, foulant concentration and ionic concentration of the solution on Fouling were investigated in order to elucidate the Fouling mechanism. Significant water flux reductions and changes in membrane surface properties were observed after static adsorption for all membranes. The possible mechanisms for the attractive interactions between polyphenolic compound and membrane are discussed. Results from UF experiments indicate that both reversible and irreversible Fouling have contributed to the overall Fouling.

Seungkwan Hong - One of the best experts on this subject based on the ideXlab platform.

  • comparison of Fouling Behavior in forward osmosis fo and reverse osmosis ro
    Journal of Membrane Science, 2010
    Co-Authors: Menachem Elimelech, Seungkwan Hong
    Abstract:

    Abstract Fouling Behaviors during forward osmosis (FO) and reverse osmosis (RO) are compared. Alginate, humic acid, and bovine serum albumin (BSA) are used as model organic foulants, and two suspensions of silica colloids of different sizes are chosen as model particulate foulants. To allow meaningful comparison of Fouling Behavior, identical hydrodynamic operating conditions (i.e., initial permeate flux and cross-flow velocity) and feed water chemistries (i.e., pH, ionic strength, and calcium concentration) are employed during FO and RO Fouling runs. The observed flux-decline Behavior in FO changed dramatically with the type of organic foulant, size of colloidal foulant, and the type of the draw solution employed to generate the osmotic driving force. Based on these experimental data and the systematic comparisons of Fouling Behaviors of FO and RO, we provide new insights into the mechanisms governing FO Fouling. In FO, reverse diffusion of salt from the draw solution to the feed side exacerbates the cake-enhanced osmotic pressure within the Fouling layer. The elevated osmotic pressure near the membrane surface on the feed side leads to a substantial drop in the net osmotic driving force and, thus, significant decline of permeate flux. Our results further suggest that the structure (i.e., thickness and compactness) of the Fouling layers of FO and RO is quite different. By varying the cross-flow velocity during the organic Fouling runs, we were able to examine the Fouling reversibility in FO and RO. The permeate flux during organic Fouling in FO recovered almost completely with increasing cross-flow velocity, while no noticeable change was observed for the RO system. Our results suggest that organic Fouling in FO could be controlled effectively by optimizing the hydrodynamics in the feed stream without employing chemical cleaning.

  • Fouling Behavior of a pilot scale inside out hollow fiber uf membrane during dead end filtration of tertiary wastewater
    Journal of Membrane Science, 2001
    Co-Authors: James Decarolis, Seungkwan Hong, James S Taylor
    Abstract:

    A series of pilot-scale filtration experiments were performed systematically under various operating conditions to investigate the Fouling Behavior of ultrafiltration (UF) membranes to treat tertiary wastewater for resuse. All experiments were conducted using a pilot system, which consisted of six inside-out capillary polyether sulfone UF membrane modules (molecular-weight cutoff = 150,000 Da), arranged in parallel configuration. The pilot unit was operated in dead-end filtration mode and the membranes were frequently backwashed with chlorinated water. Results of this research clearly indicated that the productivity of the UF membranes, measured by the specific water flux (Kw), declined much faster as operating flux increased. This observation was attributed to enhanced solid and organic loading to the membrane surface at higher operating fluxes. Furthermore, the analysis of Kw variation against filtrate volume showed larger productivity reduction per foulant mass loading during operation at high flux rates, suggesting the formation of more compact cake layers which were not easily removed during backwashing. Pilot study results also demonstrated that increasing backwashing with chlorine addition significantly improved membrane productivity, primarily due to enhanced foulant removal by organic oxidation and biogrowth control. In addition, flux enhancement per backwashing volume increased with decreasing time between backwashing events. Ferric chloride pretreatment also markedly enhanced membrane productivity by increasing particle floc size, which led to decreased pore plugging, reduced cake layer resistance, and enhanced backwashing efficiency. © 2001 Elsevier Science B.V. All rights reserved.

  • Role of membrane surface morphology in colloidal Fouling of cellulose acetate and composite aromatic polyamide reverse osmosis membranes
    Journal of Membrane Science, 1997
    Co-Authors: Menachem Elimelech, Amy E. Childress, Xiaohua Zhu, Seungkwan Hong
    Abstract:

    Laboratory-scale colloidal Fouling tests, comparing the Fouling Behavior of cellulose acetate and aromatic polyamide thin-film composite reverse osmosis (RO) membranes, are reported. Fouling of both membranes was studied at identical initial permeation rates so that the effect of the transverse hydrodnamic force (permeation drag) on the Fouling of both membranes is comparable. Results showed a significantly higher Fouling rate for the thin-film composite membranes compared to that for the cellulose acetate membranes. Addition of an anionic surfactant (sodium dodecyl sulfate, SDS) to mask variations in chemical and electrokinetic surface characteristics of the cellulose acetate and aromatic polyamide membranes resulted in only a small change in the Fouling Behavior. The higher Fouling rate for the thin-film composite membranes is attributed to surface roughness which is inherent in interfacially polymerized aromatic polyamide composite membranes. AFM and SEM images of the two membrane surfaces strongly support this conclusion. These surface images reveal that the thin-film composite membrane exhibits large-scale surface toughness of ridge-and-valley structure, while the cellulose acetate membrane surface is relatively smooth.