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Andrew L. Zydney - One of the best experts on this subject based on the ideXlab platform.
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effects of membrane pore geometry on fouling behavior during yeast cell microFiltration
Journal of Membrane Science, 2006Co-Authors: Martin Chandler, Andrew L. ZydneyAbstract:The effects of the pore geometry on yeast cell fouling during microFiltration were studied using novel micro-patterned membranes having well-defined slot-shaped or circular pores. Normal flow Filtration experiments were performed with Baker's yeast suspensions. The flux decline data were consistent with initial fouling by pore blockage followed by Cake Filtration. The specific resistance of the Cake layer was a function of both the pore geometry and the overall membrane porosity. The initial rate of flux decline was slower for the membrane with slotted pores compared to the membrane with circular pores since the initial cell deposition only covered a small fraction of the slotted pore due to its high aspect ratio. The data then show a transition to Cake Filtration, with the nature of the transition also a function of the underlying pore geometry. A simple geometric model was developed to describe the Cake growth phenomenon on slotted pore membranes. These results provide important insights into the effects of pore geometry on membrane fouling.
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transmembrane pressure profiles during constant flux microFiltration of bovine serum albumin
Journal of Membrane Science, 2002Co-Authors: Chiachi Ho, Andrew L. ZydneyAbstract:Many microFiltration systems are now run at constant filtrate flux to achieve improved performance; however, large increases in transmembrane pressure are often required to maintain the flux at a constant value due to membrane fouling. We have developed a new mathematical model to describe the change in transmembrane pressure during constant flux microFiltration. Fouling is assumed to occur first by pore blockage, with a Cake then forming over the blocked areas of the membrane. This combined pore blockage-Cake Filtration model is in good agreement with experimental data obtained during the constant flux Filtration of bovine serum albumin through track-etched microFiltration membranes. The total volume of the feed solution that can be filtered through the membrane before the transmembrane pressure exceeds some critical value increases with decreasing flux due to the reduction in the rate of Cake growth at low flux. Model simulations were used to provide important insights into the design and operation of constant flux microFiltration processes.
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analysis of humic acid fouling during microFiltration using a pore blockage Cake Filtration model
Journal of Membrane Science, 2002Co-Authors: Wei Yuan, Aleksandra Kocic, Andrew L. ZydneyAbstract:Fouling by natural organic matter, such as humic substances, is a major factor limiting the use of microFiltration for water purification. The objective of this study was to develop a fundamental understanding of the underlying mechanisms governing humic acid fouling during microFiltration using a combined pore blockage–Cake Filtration model. Data were obtained over a range of humic acid concentrations, transmembrane pressures, and stirring speeds. The initial flux decline was due to pore blockage caused by the deposition of large humic acid aggregates on the membrane surface, with a humic acid deposit developing over those regions of the membrane that have first been blocked by an aggregate. The rate of Cake growth approaches zero at a finite filtrate flux, similar to the critical flux concept developed for colloidal Filtration. The data were in good agreement with model calculations, with the parameter values providing important insights into the mechanisms governing humic acid fouling during microFiltration. In addition, the basic approach provides a framework that can be used to analyze humic acid fouling under different conditions.
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a combined pore blockage and Cake Filtration model for protein fouling during microFiltration
Journal of Colloid and Interface Science, 2000Co-Authors: Chiachi Ho, Andrew L. ZydneyAbstract:Previous studies of protein fouling during microFiltration have shown significant discrepancies between filtrate flux data and predictions of the classical pore blockage, pore constriction, and Cake Filtration models. A new mathematical model was developed for the filtrate flux which accounts for initial fouling due to pore blockage and subsequent fouling due to the growth of a protein Cake or deposit over these initially blocked regions. The model explicitly accounts for the inhomogeneity in the Cake layer thickness over different regions of the membrane arising from the time-dependent blockage of the pore surface. The model was shown to be in excellent agreement with experimental data obtained during the stirred cell Filtration of bovine serum albumin solutions through polycarbonate track-etched microFiltration membranes over the entire course of the Filtration. The model provides a smooth transition from the pore blockage to Cake Filtration regimes, eliminating the need to use different mathematical formulations to describe these two phenomena. In addition, the model provides the first quantitative explanation for some of the unusual observations reported previously in investigations of protein microFiltration. The results provide important insights into the underlying mechanisms of protein fouling during microFiltration.
Nunes, Deivid Marques - One of the best experts on this subject based on the ideXlab platform.
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Estudo sobre o efeito de vibrações axiais sobre a formação e remoção de tortas de filtração gás-sólidos
Universidade Federal de Uberlândia, 2017Co-Authors: Nunes, Deivid MarquesAbstract:Com o intuito de tornar a operação de filtração de gases mais eficiente, o objetivo desse trabalho foi adaptar um sistema de filtração com motor vibrador acoplado axial ao fluxo gasoso que possibilitasse o desprendimento da torta de filtração sem a necessidade de parar a operação de filtração, além de avaliar a influências das frequências de vibração mecânica na formação das tortas quanto às forças de arraste no meio filtrante, espessuras das tortas, resistências específicas das tortas, porosidades das tortas em comparação com o sistema ausente de vibração. Foram utilizados como materiais particulados o polvilho doce, o talco puro e a rocha fosfática moída, a fim de verificar a influência da vibração em materiais particulados com diferentes morfologias e distribuição granulométrica. A velocidade de filtração superficial do fluxo gasoso foi de 10 cm/s, a uma vazão mássica de 0,183 g/s e queda de pressão máxima estabelecida de 10000 Pa. As porosidades das tortas de filtração foram determinadas por correlações encontradas na literatura. Os resultados mostraram que para as frequências de vibrações mecânicas de 12, 17 e 18 Hz influenciaram na estrutura da torta e em sua remoção para o material particulado rocha fosfática moída, cuja circularidade era de 0,60, causando a formação de tortas menos espessas, mais resistentes e menos porosas quando comparadas ao sistema estático. As forças de adesão desse material também foram maiores para as frequências de vibração que o sistema estático. Concluiu-se que as vibrações mecânicas causaram um empacotamento mais denso das partículas de rocha moída no meio filtrante. Já para o material particulado, o talco puro, cuja circularidade era de 0,67, as vibrações mecânicas tanto para o sistema independente quanto ao sistema intermitente proporcionam comportamentos semelhantes ao sistema estático, não sendo viável sua utilização. Para as partículas de polvilho doce, cuja circularidade se aproxima de um círculo perfeito, 0,98, para a frequência de vibração de 12 Hz independente possibilitou a formação de tortas com maiores espessuras, menores resistências específicas das tortas e maiores porosidades quando comparadas ao sistema estático, além de menor força de adesão quando comparadas ao sistema estático. Isso possivelmente estar relacionado ao surgimento de lacunas nas tortas e à distribuição das partículas nas camadas das tortas. Enfim, o sistema de vibração mecânica independente e intermitente não possibilitou o desprendimento das tortas de filtração, porém influenciou a estrutura de formação das tortas.Many studies related to the Filtration of gases for the control and recovery of particulate materials have been developed with the aim of making the Filtration system, both in the gas Filtration operation as in the cleaning operation, more effective, with a longer useful life of the fabric filters and with greater ease of removal of Cake Filtration, tanking into account the currente laws regarding the emission of pollutants not environment and reduction of maintenance and operation costs. In this context, in order to make the gas Filtration operation more efficient, the objective of this work was to adapt a Filtration system with vibration motor coupled axially to the gaseous flow that would allow the detachment of the filter Cake without the need to stop the operation Filtration, and to evaluate the influences of mechanical vibration frequencies in the formation of Cakes as the forces of drag on the filter medium, the thickness of Cakes Filtration, specific resistance of Cake, porosity of Cake compared with the static system. The manioc starch powder, pure talcum powder and phosphate rock were used as particulates in order to verify the influence of vibration on particulates with different morphologies and granulometric distribution. The surface Filtration velocity of the gaseous stream was 10 cm / s at a mass flow rate of 0.183 g / s and the maximum pressure drop was 10000 Pa. The porosities of the Cake Filtration were determined by correlations found in the literature. The results showed that the frequencies of mechanical vibration 12, 17 and 18Hz influenced the structure of the Cake and its removal for the rock phosphate particulate material, whose circularity was of 0.60, causing a formation of thinner of Cake filtrantion, more resistant Cake Filtration and less porous Cake filtrantion when compared to the static system. As adhesion forces of material also higher for vibration frequencies than the static system. It was concluded that the mechanical vibrations caused a denser packing of the phosphate rock particles in the filter medium. As for the particulate material, pure talcum powder, , whose circularity was of 0.67, the mechanical vibrations to both the independent system and the intermittent system provide behavior similar to the static system, it is not feasible to use. For the particles of manioc starch, whose circularity approaches a perfect circle, 0.98, for the independent vibration frequency of 12 Hz allowed the formation of Cake Filtration with greater thicknesses, smaller specific resistances of the Cake filtrantion and larger porosities when compared to the static system, as well as lower adhesion force when compared to the static system. This may be related to the appearance of gaps in the Cake Filtration and the distribution of the particles in the layers of the Cake Filtration. Finally, the system of independent and intermittent mechanical vibration did not allow the detachment of the filter Cake, but influenced the structure of the Cake formation
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Estudo sobre o efeito de vibrações axiais sobre a formação e remoção de tortas de filtração gás-sólidos
'EDUFU - Editora da Universidade Federal de Uberlandia', 2017Co-Authors: Nunes, Deivid MarquesAbstract:Many studies related to the Filtration of gases for the control and recovery of particulate materials have been developed with the aim of making the Filtration system, both in the gas Filtration operation as in the cleaning operation, more effective, with a longer useful life of the fabric filters and with greater ease of removal of Cake Filtration, tanking into account the currente laws regarding the emission of pollutants not environment and reduction of maintenance and operation costs. In this context, in order to make the gas Filtration operation more efficient, the objective of this work was to adapt a Filtration system with vibration motor coupled axially to the gaseous flow that would allow the detachment of the filter Cake without the need to stop the operation Filtration, and to evaluate the influences of mechanical vibration frequencies in the formation of Cakes as the forces of drag on the filter medium, the thickness of Cakes Filtration, specific resistance of Cake, porosity of Cake compared with the static system. The manioc starch powder, pure talcum powder and phosphate rock were used as particulates in order to verify the influence of vibration on particulates with different morphologies and granulometric distribution. The surface Filtration velocity of the gaseous stream was 10 cm / s at a mass flow rate of 0.183 g / s and the maximum pressure drop was 10000 Pa. The porosities of the Cake Filtration were determined by correlations found in the literature. The results showed that the frequencies of mechanical vibration 12, 17 and 18Hz influenced the structure of the Cake and its removal for the rock phosphate particulate material, whose circularity was of 0.60, causing a formation of thinner of Cake filtrantion, more resistant Cake Filtration and less porous Cake filtrantion when compared to the static system. As adhesion forces of material also higher for vibration frequencies than the static system. It was concluded that the mechanical vibrations caused a denser packing of the phosphate rock particles in the filter medium. As for the particulate material, pure talcum powder, , whose circularity was of 0.67, the mechanical vibrations to both the independent system and the intermittent system provide behavior similar to the static system, it is not feasible to use. For the particles of manioc starch, whose circularity approaches a perfect circle, 0.98, for the independent vibration frequency of 12 Hz allowed the formation of Cake Filtration with greater thicknesses, smaller specific resistances of the Cake filtrantion and larger porosities when compared to the static system, as well as lower adhesion force when compared to the static system. This may be related to the appearance of gaps in the Cake Filtration and the distribution of the particles in the layers of the Cake Filtration. Finally, the system of independent and intermittent mechanical vibration did not allow the detachment of the filter Cake, but influenced the structure of the Cake formation.Tese (Doutorado)Com o intuito de tornar a operação de filtração de gases mais eficiente, o objetivo desse trabalho foi adaptar um sistema de filtração com motor vibrador acoplado axial ao fluxo gasoso que possibilitasse o desprendimento da torta de filtração sem a necessidade de parar a operação de filtração, além de avaliar a influências das frequências de vibração mecânica na formação das tortas quanto às forças de arraste no meio filtrante, espessuras das tortas, resistências específicas das tortas, porosidades das tortas em comparação com o sistema ausente de vibração. Foram utilizados como materiais particulados o polvilho doce, o talco puro e a rocha fosfática moída, a fim de verificar a influência da vibração em materiais particulados com diferentes morfologias e distribuição granulométrica. A velocidade de filtração superficial do fluxo gasoso foi de 10 cm/s, a uma vazão mássica de 0,183 g/s e queda de pressão máxima estabelecida de 10000 Pa. As porosidades das tortas de filtração foram determinadas por correlações encontradas na literatura. Os resultados mostraram que para as frequências de vibrações mecânicas de 12, 17 e 18 Hz influenciaram na estrutura da torta e em sua remoção para o material particulado rocha fosfática moída, cuja circularidade era de 0,60, causando a formação de tortas menos espessas, mais resistentes e menos porosas quando comparadas ao sistema estático. As forças de adesão desse material também foram maiores para as frequências de vibração que o sistema estático. Concluiu-se que as vibrações mecânicas causaram um empacotamento mais denso das partículas de rocha moída no meio filtrante. Já para o material particulado, o talco puro, cuja circularidade era de 0,67, as vibrações mecânicas tanto para o sistema independente quanto ao sistema intermitente proporcionam comportamentos semelhantes ao sistema estático, não sendo viável sua utilização. Para as partículas de polvilho doce, cuja circularidade se aproxima de um círculo perfeito, 0,98, para a frequência de vibração de 12 Hz independente possibilitou a formação de tortas com maiores espessuras, menores resistências específicas das tortas e maiores porosidades quando comparadas ao sistema estático, além de menor força de adesão quando comparadas ao sistema estático. Isso possivelmente estar relacionado ao surgimento de lacunas nas tortas e à distribuição das partículas nas camadas das tortas. Enfim, o sistema de vibração mecânica independente e intermitente não possibilitou o desprendimento das tortas de filtração, porém influenciou a estrutura de formação das tortas
Chiachi Ho - One of the best experts on this subject based on the ideXlab platform.
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transmembrane pressure profiles during constant flux microFiltration of bovine serum albumin
Journal of Membrane Science, 2002Co-Authors: Chiachi Ho, Andrew L. ZydneyAbstract:Many microFiltration systems are now run at constant filtrate flux to achieve improved performance; however, large increases in transmembrane pressure are often required to maintain the flux at a constant value due to membrane fouling. We have developed a new mathematical model to describe the change in transmembrane pressure during constant flux microFiltration. Fouling is assumed to occur first by pore blockage, with a Cake then forming over the blocked areas of the membrane. This combined pore blockage-Cake Filtration model is in good agreement with experimental data obtained during the constant flux Filtration of bovine serum albumin through track-etched microFiltration membranes. The total volume of the feed solution that can be filtered through the membrane before the transmembrane pressure exceeds some critical value increases with decreasing flux due to the reduction in the rate of Cake growth at low flux. Model simulations were used to provide important insights into the design and operation of constant flux microFiltration processes.
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a combined pore blockage and Cake Filtration model for protein fouling during microFiltration
Journal of Colloid and Interface Science, 2000Co-Authors: Chiachi Ho, Andrew L. ZydneyAbstract:Previous studies of protein fouling during microFiltration have shown significant discrepancies between filtrate flux data and predictions of the classical pore blockage, pore constriction, and Cake Filtration models. A new mathematical model was developed for the filtrate flux which accounts for initial fouling due to pore blockage and subsequent fouling due to the growth of a protein Cake or deposit over these initially blocked regions. The model explicitly accounts for the inhomogeneity in the Cake layer thickness over different regions of the membrane arising from the time-dependent blockage of the pore surface. The model was shown to be in excellent agreement with experimental data obtained during the stirred cell Filtration of bovine serum albumin solutions through polycarbonate track-etched microFiltration membranes over the entire course of the Filtration. The model provides a smooth transition from the pore blockage to Cake Filtration regimes, eliminating the need to use different mathematical formulations to describe these two phenomena. In addition, the model provides the first quantitative explanation for some of the unusual observations reported previously in investigations of protein microFiltration. The results provide important insights into the underlying mechanisms of protein fouling during microFiltration.
Ratana Jiraratanano - One of the best experts on this subject based on the ideXlab platform.
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a combined pore blockage osmotic pressure and Cake Filtration model for crossflow nanoFiltration of natural organic matter and inorganic salts
Desalination, 2011Co-Authors: Supatpong Mattaraj, Chalo Jarusutthirak, Chareopo Charoensuk, Ratana JiraratananoAbstract:Abstract The performance of nanoFiltration (NF) process for water treatment is affected by flux decline due to membrane fouling. Many models have been applied to explain fouling mechanisms. In this work, a combined pore blockage, osmotic pressure, and Cake Filtration model was developed and successfully used to determine NF performance and model parameters for crossflow NF. NOM solutions containing sparingly soluble inorganic salts (i.e. CaCO 3 , CaSO 4 , and Ca 3 (PO 4 ) 2 ), showed higher normalized flux decline than those containing soluble inorganic salts (i.e. NaCl and CaCl 2 ). The α blocked and R m,s parameters for sparingly soluble inorganic salts exhibited higher values than those for soluble inorganic salts, while the R m,s and α Cake parameters were found to be significant for soluble inorganic salts due to increased salt concentration and NOM Cake accumulation at the membrane surface. Increased ionic strengths from 0.01 M to 0.11 M resulted in more pronounced flux decline, thus increased model parameters (i.e. α blocked and R m,s ). The membrane surface characteristics examined by the scanning electron microscopy (SEM) images evidently supported the precipitation of sparingly soluble inorganic salts. The flux decline was the most pronounced for phosphate species, corresponding to the lowest water flux recovery, thus increased non-recoverable resistance ( R non-rec ) due to pore plugging from phosphate salt precipitation.
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a combined osmotic pressure and Cake Filtration model for crossflow nanoFiltration of natural organic matter
Journal of Membrane Science, 2008Co-Authors: Supatpong Mattaraj, Chalo Jarusutthirak, Ratana JiraratananoAbstract:Abstract A combined osmotic pressure and Cake Filtration model for crossflow nanoFiltration of natural organic matter (NOM) was developed and successfully used to determine model parameters (i.e. permeability reduction factor ( η ) and specific Cake resistance ( α Cake )) for salt concentrations, NOM concentrations, and ionic strength of salt species (Na + and Ca ++ ). In the absence of NOM, with increasing salt concentration from 0.004 to 0.1 M, permeability reduction factor ( η )) decreased from 0.99 to 0.72 and 0.94 to 0.44 for monovalent cation (Na + ) and divalent cation (Ca ++ ), respectively. This reduced membrane permeability was due to salt concentrations and salt species. In the presence of NOM, specific Cake resistance tended to increase with increasing NOM concentration and ionic strength in the range of 0.85 × 10 15 –3.66 × 10 15 m kg −1 . Solutions containing divalent cation exhibited higher normalized flux decline ( J v / J vo = 0.685–0.632) and specific Cake resistance ( α Cake = 2.89 × 10 15 –6.24 × 10 15 m kg −1 ) than those containing monovalent cation, indicating a highly compacted NOM accumulation, thus increased permeate flow resistance during NF Filtration experiments. After membrane cleaning, divalent cation exhibited lower water flux recovery than monovalent cation, suggesting higher non-recoverable ( R non-rec ) resistance than monovalent cation.
Heng Liang - One of the best experts on this subject based on the ideXlab platform.
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effect of sulfate radical based oxidation pretreatments for mitigating ceramic uf membrane fouling caused by algal extracellular organic matter
Water Research, 2018Co-Authors: Xiaoxiang Cheng, Heng Liang, Xuewu Zhu, Xiaobin Tang, Zhendong Gan, Jiajian Xing, Xinsheng LuoAbstract:Abstract Algal extracellular organic matter (EOM) released from Microcystis aeruginosa can cause severe membrane fouling during algae-laden water treatment. To solve this problem, three typical sulfate radical-based advanced oxidation processes (SR-AOPs), i.e., ferrous iron/peroxymonosulfate (Fe(II)/PMS), UV/PMS and UV/Fe(II)/PMS, were employed as membrane pretreatment strategies. Their performance on mitigating EOM fouling of a ceramic UF membrane was systematically investigated and compared in the present study. The results indicated that SR-AOPs pretreatments could promote the reduction of DOC and UV254, and the removal performance showed an apparent regularity of UV/Fe(II)/PMS > Fe(II)/PMS > UV/PMS. The pretreatments were very effective for decomposing high-MW biopolymers (>20,000 Da) into low-MW humic substances (1000–20,000 Da), thus reducing the accumulation of high-MW biopolymers on membrane surface. With respect to membrane fouling control, Fe(II)/PMS significantly mitigated both reversible and irreversible membrane fouling, whereas UV/PMS only reduced reversible fouling, and exhibited little effect on irreversible fouling. By contrast, UV/Fe(II)/PMS showed the best performance for fouling reduction due to the synergistic effect of UV and Fe(II) for PMS activation. The dominating fouling mechanism was governed by both pore blockage and Cake Filtration, likely due to the bimodal MW distribution of EOM, and SR-AOPs pretreatments delayed the transition from pore blockage to Cake Filtration. In addition, SR-AOPs prior to UF membrane were also very effective to improve the removal of micropollutants (i.e., ATZ, SMT and p-CNB). These results demonstrate the potential application of SR-AOPs as pretreatment for membrane fouling control during algae-laden water treatment.
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control of ultraFiltration membrane fouling caused by algal extracellular organic matter eom using enhanced al coagulation with permanganate
Separation and Purification Technology, 2017Co-Authors: Fangshu Qu, An Ding, Heng Liang, Yan Zhao, Guibai LiAbstract:Abstract This work was aimed to investigate the mechanism for the control of ultraFiltration (UF) membrane fouling caused by algal extracellular organic matter (EOM) using permanganate enhanced aluminum (Al) coagulation. Impacts of Al coagulation, permanganate (KMnO 4 )-aided Al coagulation and in-situ formed manganese oxide (MnO 2 )-aided coagulation on EOM fouling evolution were compared with respect to EOM characteristics and fouling indexes. The Al coagulation using polymeric aluminum (0.4 mg Al mg −1 DOC) alone substantially alleviated the flux decline caused by EOM via reducing organic amounts by 18% and preferentially removing the high-molecular-weight (MW) (>100 kDa) components of EOM. The KMnO 4 -aided Al coagulation obtained even better organic removal than the Al coagulation, especially for the fluorescent components of EOM, due to oxidative degradation and adsorption provided by manganese oxide, and thus resulted in the improved performance in fouling control. The best membrane permeability and fouling reversibility were achieved by the MnO 2 -aided Al coagulation, probably attributed to adsorption of the hydrophilic fractions of EOM on in-situ formed MnO 2 particles. In terms of fouling mechanisms, EOM fouling was governed by multiple mechanisms with standard blocking and Cake Filtration dominating the fouling formation. The enhanced Al coagulation with KMnO 4 or in situ formed MnO 2 particles decreased the role of Cake Filtration but boosted the impact of standard blocking by preferentially removing the high-MW biopolymers.
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effect of granular activated carbon addition on the effluent properties and fouling potentials of membrane coupled expanded granular sludge bed process
Bioresource Technology, 2014Co-Authors: An Ding, Heng Liang, Langming Bai, Huu Hao Ngo, Wenshan GuoAbstract:To mitigate membrane fouling of membrane-coupled anaerobic process, granular activated carbon (GAC: 50 g/L) was added into an expanded granular sludge bed (EGSB). A short-term ultraFiltration test was investigated for analyzing membrane fouling potential and underlying fouling mechanisms. The results showed that adding GAC into the EGSB not only improved the COD removal efficiency, but also alleviated membrane fouling efficiently because GAC could help to reduce soluble microbial products, polysaccharides and proteins by 26.8%, 27.8% and 24.7%, respectively, compared with the control system. Furthermore, excitation emission matrix (EEM) fluorescence spectroscopy analysis revealed that GAC addition mainly reduced tryptophan protein-like, aromatic protein-like and fulvic-like substances. In addition, the resistance distribution analysis demonstrated that adding GAC primarily decreased the Cake layer resistance by 53.5%. The classic Filtration mode analysis showed that Cake Filtration was the major fouling mechanism for membrane-coupled EGSB process regardless of the GAC addition.
