The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Zhiqiang Zhang - One of the best experts on this subject based on the ideXlab platform.
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Enhancement mechanisms of short-time Aerobic Digestion for waste activated sludge in the presence of cocoamidopropyl betaine.
Scientific reports, 2017Co-Authors: Siqing Xia, Yun Zhou, Everett Eustance, Zhiqiang ZhangAbstract:Cocoamidopropyl betaine (CAPB), which is a biodegradable ampholytic surfactant, has recently been found to dramatically enhance the Aerobic Digestion of waste activated sludge (WAS) in short-time Aerobic Digestion (STAD) systems. Therefore, it is important to understand the mechanisms in which CAPB enhances WAS Aerobic Digestion performance. Results showed that CAPB could dramatically enhance the solubilization of soluble proteins (PN), polysaccharides (PS), nucleic acids (NA) and humic-like substances (HS) in the STAD system within the initial 2 h. Then PN, PS and NA gradually decreased, while HS showed only minor decease. In addition, CAPB increased the proportion of low MW fractions (
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enhancement mechanisms of short time Aerobic Digestion for waste activated sludge in the presence of cocoamidopropyl betaine
Scientific Reports, 2017Co-Authors: Siqing Xia, Yun Zhou, Everett Eustance, Zhiqiang ZhangAbstract:Cocoamidopropyl betaine (CAPB), which is a biodegradable ampholytic surfactant, has recently been found to dramatically enhance the Aerobic Digestion of waste activated sludge (WAS) in short-time Aerobic Digestion (STAD) systems. Therefore, it is important to understand the mechanisms in which CAPB enhances WAS Aerobic Digestion performance. Results showed that CAPB could dramatically enhance the solubilization of soluble proteins (PN), polysaccharides (PS), nucleic acids (NA) and humic-like substances (HS) in the STAD system within the initial 2 h. Then PN, PS and NA gradually decreased, while HS showed only minor decease. In addition, CAPB increased the proportion of low MW fractions (<20 kDa) from 4.22% to 39.4%, which are more biodegradable. Specific oxygen uptake rates and dehydrogenase enzyme activity results indicated that CAPB markedly improved the Aerobic microorganism activities. Microbial community analyses and principle coordinate analyses (PCoA) revealed that CAPB increased the proportion of some functional microorganisms, including Proteobacteria, Planctomycetales, Acinetobacter, Pseudomonas and Aeromonas. The changes driven by CAPB could explain the enhanced performance of the STAD system for WAS Aerobic treatment.
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Enhanced performance of short-time Aerobic Digestion for waste activated sludge under the presence of cocoamidopropyl betaine
Chemical Engineering Journal, 2017Co-Authors: Yun Zhou, Jiao Zhang, Zhiqiang Zhang, Chen Zhou, Yenjung Sean Lai, Siqing XiaAbstract:Abstract Short-time Aerobic Digestion (STAD) is a promising technique for waste activated sludge (WAS) stabilization. As a widely used surfactant, cocoamidopropyl betaine (CAPB) could enter wastewater treatment system and influence the WAS properties. It is of big significance to ascertain its influences on the STAD of WAS. CAPB was found to promote the fast removal of organics in WAS. Within 24 h, the removal rate of VSS was up to 28.3%, while no more than 20% was reported in previous studies. The biodegradation rate constants of both VSS and TCOD were increased over 65%. Due to special features of surfactant, CAPB aroused rapid releases of SCOD, PO 4 3 - -P , NH 4 + -N and TN within 2 h, and then their values gradually decreased under the Aerobic Digestion. CAPB was also biodegraded by the system, and the removal rate at 24 h was 91.2%. The biodegradation route contained extracellular adsorption/desorption and Aerobic biodegradation. Biodegradable CAPB could lead to a promising performance of the STAD process for WAS and resulted in zero waste discharge from the treatment system.
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effects of short time Aerobic Digestion on extracellular polymeric substances and sludge features of waste activated sludge
Chemical Engineering Journal, 2016Co-Authors: Zhiqiang Zhang, Yun Zhou, Jiao Zhang, Slawomir W HermanowiczAbstract:Abstract Aerobic Digestion is an important stabilization process for waste activated sludge. However, extended Aerobic Digestion consumes substantial oxygen and increases the running cost (oxygen demand and sludge production) and CO 2 emission. To tackle these issues, this study investigated the effects of short-time Aerobic Digestion (STAD) on microbial extracellular polymeric substances (EPS), sludge features, and their correlations. The levels of proteins and polysaccharides in EPS consistently increased as the Aerobic Digestion time increased. Nucleic acid in EPS increased only within the first 4 h and then decreased. With an extended Digestion time, sludge floc size (Dv50) increased by 4.67%, and the sludge volume index (SVI) increased by 5.06%, indicative of a deteriorating settleability. The sludge after STAD exhibited better flocculability and dewaterability than that after the prolonged Aerobic Digestion. Proteins and polysaccharides in the EPS significantly correlated with Dv50 ( R 2 = 0.97, P = 0.00 and R 2 = 0.92, P = 0.00, respectively), SVI ( R 2 = 0.88, P = 0.00 and R 2 = 0.93, P = 0.00, respectively), effluent suspended solids (ESS, R 2 = 0.68, P = 0.01 and R 2 = 0.82, P = 0.00, respectively) and the normalized capillary suction time (CST, R 2 = 0.66, P = 0.01 and R 2 = 0.78, P = 0.00, respectively). No significant correlation was found between nucleic acid and these sludge features. These results indicated that proteins and polysaccharides in EPS may govern sludge floc size, settleability, flocculability and dewaterability. Interestingly, good sludge flocculability and dewaterability were observed when the proteins and polysaccharides in EPS were lower than 21.55 and 12.27 mg/g VSS, respectively.
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effect of short time Aerobic Digestion on bioflocculation of extracellular polymeric substances from waste activated sludge
Environmental Science and Pollution Research, 2015Co-Authors: Zhiqiang Zhang, Jiao Zhang, Jianfu ZhaoAbstract:The effect of short-time Aerobic Digestion on bioflocculation of extracellular polymeric substances (EPSs) from waste activated sludge (WAS) was investigated. Bioflocculation of the EPS was found to be enhanced by 2∼6 h of WAS Aerobic Digestion under the conditions of natural sludge pH (about 7), high sludge concentration by gravity thickening, and dissolved oxygen of about 2 mg/L. With the same EPS extraction method, the total suspended solid content reduction of 0.20 and 0.36 g/L and the volatile suspended solid content reduction of 0.19 and 0.26 g/L were found for the WAS samples before and after Aerobic Digestion of 4 h. It indicates that more EPS is produced by short-time Aerobic Digestion of WAS. The scanning electron microscopy images of the WAS samples before and after Aerobic Digestion of 4 h showed that more EPS appeared on the surface of zoogloea by Aerobic Digestion, which reconfirmed that WAS Aerobic Digestion induced abundant formation of EPS. By WAS Aerobic Digestion, the flocculating rate of the EPS showed about 31 % growth, almost consistent with the growth of its yield (about 34 %). The EPSs obtained before and after the Aerobic Digestion presented nearly the same components, structures, and Fourier transform infrared spectra. These results revealed that short-time Aerobic Digestion of WAS enhanced the flocculation of the EPS by promoting its production.
Yun Zhou - One of the best experts on this subject based on the ideXlab platform.
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Enhancement mechanisms of short-time Aerobic Digestion for waste activated sludge in the presence of cocoamidopropyl betaine.
Scientific reports, 2017Co-Authors: Siqing Xia, Yun Zhou, Everett Eustance, Zhiqiang ZhangAbstract:Cocoamidopropyl betaine (CAPB), which is a biodegradable ampholytic surfactant, has recently been found to dramatically enhance the Aerobic Digestion of waste activated sludge (WAS) in short-time Aerobic Digestion (STAD) systems. Therefore, it is important to understand the mechanisms in which CAPB enhances WAS Aerobic Digestion performance. Results showed that CAPB could dramatically enhance the solubilization of soluble proteins (PN), polysaccharides (PS), nucleic acids (NA) and humic-like substances (HS) in the STAD system within the initial 2 h. Then PN, PS and NA gradually decreased, while HS showed only minor decease. In addition, CAPB increased the proportion of low MW fractions (
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enhancement mechanisms of short time Aerobic Digestion for waste activated sludge in the presence of cocoamidopropyl betaine
Scientific Reports, 2017Co-Authors: Siqing Xia, Yun Zhou, Everett Eustance, Zhiqiang ZhangAbstract:Cocoamidopropyl betaine (CAPB), which is a biodegradable ampholytic surfactant, has recently been found to dramatically enhance the Aerobic Digestion of waste activated sludge (WAS) in short-time Aerobic Digestion (STAD) systems. Therefore, it is important to understand the mechanisms in which CAPB enhances WAS Aerobic Digestion performance. Results showed that CAPB could dramatically enhance the solubilization of soluble proteins (PN), polysaccharides (PS), nucleic acids (NA) and humic-like substances (HS) in the STAD system within the initial 2 h. Then PN, PS and NA gradually decreased, while HS showed only minor decease. In addition, CAPB increased the proportion of low MW fractions (<20 kDa) from 4.22% to 39.4%, which are more biodegradable. Specific oxygen uptake rates and dehydrogenase enzyme activity results indicated that CAPB markedly improved the Aerobic microorganism activities. Microbial community analyses and principle coordinate analyses (PCoA) revealed that CAPB increased the proportion of some functional microorganisms, including Proteobacteria, Planctomycetales, Acinetobacter, Pseudomonas and Aeromonas. The changes driven by CAPB could explain the enhanced performance of the STAD system for WAS Aerobic treatment.
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Enhanced performance of short-time Aerobic Digestion for waste activated sludge under the presence of cocoamidopropyl betaine
Chemical Engineering Journal, 2017Co-Authors: Yun Zhou, Jiao Zhang, Zhiqiang Zhang, Chen Zhou, Yenjung Sean Lai, Siqing XiaAbstract:Abstract Short-time Aerobic Digestion (STAD) is a promising technique for waste activated sludge (WAS) stabilization. As a widely used surfactant, cocoamidopropyl betaine (CAPB) could enter wastewater treatment system and influence the WAS properties. It is of big significance to ascertain its influences on the STAD of WAS. CAPB was found to promote the fast removal of organics in WAS. Within 24 h, the removal rate of VSS was up to 28.3%, while no more than 20% was reported in previous studies. The biodegradation rate constants of both VSS and TCOD were increased over 65%. Due to special features of surfactant, CAPB aroused rapid releases of SCOD, PO 4 3 - -P , NH 4 + -N and TN within 2 h, and then their values gradually decreased under the Aerobic Digestion. CAPB was also biodegraded by the system, and the removal rate at 24 h was 91.2%. The biodegradation route contained extracellular adsorption/desorption and Aerobic biodegradation. Biodegradable CAPB could lead to a promising performance of the STAD process for WAS and resulted in zero waste discharge from the treatment system.
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effects of short time Aerobic Digestion on extracellular polymeric substances and sludge features of waste activated sludge
Chemical Engineering Journal, 2016Co-Authors: Zhiqiang Zhang, Yun Zhou, Jiao Zhang, Slawomir W HermanowiczAbstract:Abstract Aerobic Digestion is an important stabilization process for waste activated sludge. However, extended Aerobic Digestion consumes substantial oxygen and increases the running cost (oxygen demand and sludge production) and CO 2 emission. To tackle these issues, this study investigated the effects of short-time Aerobic Digestion (STAD) on microbial extracellular polymeric substances (EPS), sludge features, and their correlations. The levels of proteins and polysaccharides in EPS consistently increased as the Aerobic Digestion time increased. Nucleic acid in EPS increased only within the first 4 h and then decreased. With an extended Digestion time, sludge floc size (Dv50) increased by 4.67%, and the sludge volume index (SVI) increased by 5.06%, indicative of a deteriorating settleability. The sludge after STAD exhibited better flocculability and dewaterability than that after the prolonged Aerobic Digestion. Proteins and polysaccharides in the EPS significantly correlated with Dv50 ( R 2 = 0.97, P = 0.00 and R 2 = 0.92, P = 0.00, respectively), SVI ( R 2 = 0.88, P = 0.00 and R 2 = 0.93, P = 0.00, respectively), effluent suspended solids (ESS, R 2 = 0.68, P = 0.01 and R 2 = 0.82, P = 0.00, respectively) and the normalized capillary suction time (CST, R 2 = 0.66, P = 0.01 and R 2 = 0.78, P = 0.00, respectively). No significant correlation was found between nucleic acid and these sludge features. These results indicated that proteins and polysaccharides in EPS may govern sludge floc size, settleability, flocculability and dewaterability. Interestingly, good sludge flocculability and dewaterability were observed when the proteins and polysaccharides in EPS were lower than 21.55 and 12.27 mg/g VSS, respectively.
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copper ii adsorption by the extracellular polymeric substance extracted from waste activated sludge after short time Aerobic Digestion
Environmental Science and Pollution Research, 2014Co-Authors: Yun Zhou, Jiao ZhangAbstract:The extracellular polymeric substance (EPS) extracted from waste activated sludge (WAS) after short-time Aerobic Digestion was investigated to be used as a novel biosorbent for Cu2+ removal from water. The EPS consisted of protein (52.6 %, w/w), polysaccharide (30.7 %, w/w), and nucleic acid (16.7 %, w/w). Short-time Aerobic Digestion process of WAS for about 4 h promoted the productivity growth of the EPS for about 10 %. With a molecular weight of about 1.9 × 106 Da, the EPS showed a linear structure with long chains, and contained carboxyl, hydroxyl, and amino groups. The sorption kinetics was well fit for the pseudo-second-order model, and the maximum sorption capacity of the EPS (700.3 mg Cu2+/g EPS) was markedly greater than those of the reported biosorbents. Both Langmuir model and Freundlich model commendably described the sorption isotherm. The Gibbs free energy analysis of the adsorption showed that the sorption process was feasible and spontaneous. According to the complex results of multiple analytical techniques, including scanning electron microscopy, Fourier transform infrared spectroscopy, atomic force microscopy, etc., the adsorption process took place via both physical and chemical sorption, but the electrostatic interaction between sorption sites with the functional groups and Cu2+ is the major mechanism.
Jiao Zhang - One of the best experts on this subject based on the ideXlab platform.
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Enhanced performance of short-time Aerobic Digestion for waste activated sludge under the presence of cocoamidopropyl betaine
Chemical Engineering Journal, 2017Co-Authors: Yun Zhou, Jiao Zhang, Zhiqiang Zhang, Chen Zhou, Yenjung Sean Lai, Siqing XiaAbstract:Abstract Short-time Aerobic Digestion (STAD) is a promising technique for waste activated sludge (WAS) stabilization. As a widely used surfactant, cocoamidopropyl betaine (CAPB) could enter wastewater treatment system and influence the WAS properties. It is of big significance to ascertain its influences on the STAD of WAS. CAPB was found to promote the fast removal of organics in WAS. Within 24 h, the removal rate of VSS was up to 28.3%, while no more than 20% was reported in previous studies. The biodegradation rate constants of both VSS and TCOD were increased over 65%. Due to special features of surfactant, CAPB aroused rapid releases of SCOD, PO 4 3 - -P , NH 4 + -N and TN within 2 h, and then their values gradually decreased under the Aerobic Digestion. CAPB was also biodegraded by the system, and the removal rate at 24 h was 91.2%. The biodegradation route contained extracellular adsorption/desorption and Aerobic biodegradation. Biodegradable CAPB could lead to a promising performance of the STAD process for WAS and resulted in zero waste discharge from the treatment system.
-
effects of short time Aerobic Digestion on extracellular polymeric substances and sludge features of waste activated sludge
Chemical Engineering Journal, 2016Co-Authors: Zhiqiang Zhang, Yun Zhou, Jiao Zhang, Slawomir W HermanowiczAbstract:Abstract Aerobic Digestion is an important stabilization process for waste activated sludge. However, extended Aerobic Digestion consumes substantial oxygen and increases the running cost (oxygen demand and sludge production) and CO 2 emission. To tackle these issues, this study investigated the effects of short-time Aerobic Digestion (STAD) on microbial extracellular polymeric substances (EPS), sludge features, and their correlations. The levels of proteins and polysaccharides in EPS consistently increased as the Aerobic Digestion time increased. Nucleic acid in EPS increased only within the first 4 h and then decreased. With an extended Digestion time, sludge floc size (Dv50) increased by 4.67%, and the sludge volume index (SVI) increased by 5.06%, indicative of a deteriorating settleability. The sludge after STAD exhibited better flocculability and dewaterability than that after the prolonged Aerobic Digestion. Proteins and polysaccharides in the EPS significantly correlated with Dv50 ( R 2 = 0.97, P = 0.00 and R 2 = 0.92, P = 0.00, respectively), SVI ( R 2 = 0.88, P = 0.00 and R 2 = 0.93, P = 0.00, respectively), effluent suspended solids (ESS, R 2 = 0.68, P = 0.01 and R 2 = 0.82, P = 0.00, respectively) and the normalized capillary suction time (CST, R 2 = 0.66, P = 0.01 and R 2 = 0.78, P = 0.00, respectively). No significant correlation was found between nucleic acid and these sludge features. These results indicated that proteins and polysaccharides in EPS may govern sludge floc size, settleability, flocculability and dewaterability. Interestingly, good sludge flocculability and dewaterability were observed when the proteins and polysaccharides in EPS were lower than 21.55 and 12.27 mg/g VSS, respectively.
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effect of short time Aerobic Digestion on bioflocculation of extracellular polymeric substances from waste activated sludge
Environmental Science and Pollution Research, 2015Co-Authors: Zhiqiang Zhang, Jiao Zhang, Jianfu ZhaoAbstract:The effect of short-time Aerobic Digestion on bioflocculation of extracellular polymeric substances (EPSs) from waste activated sludge (WAS) was investigated. Bioflocculation of the EPS was found to be enhanced by 2∼6 h of WAS Aerobic Digestion under the conditions of natural sludge pH (about 7), high sludge concentration by gravity thickening, and dissolved oxygen of about 2 mg/L. With the same EPS extraction method, the total suspended solid content reduction of 0.20 and 0.36 g/L and the volatile suspended solid content reduction of 0.19 and 0.26 g/L were found for the WAS samples before and after Aerobic Digestion of 4 h. It indicates that more EPS is produced by short-time Aerobic Digestion of WAS. The scanning electron microscopy images of the WAS samples before and after Aerobic Digestion of 4 h showed that more EPS appeared on the surface of zoogloea by Aerobic Digestion, which reconfirmed that WAS Aerobic Digestion induced abundant formation of EPS. By WAS Aerobic Digestion, the flocculating rate of the EPS showed about 31 % growth, almost consistent with the growth of its yield (about 34 %). The EPSs obtained before and after the Aerobic Digestion presented nearly the same components, structures, and Fourier transform infrared spectra. These results revealed that short-time Aerobic Digestion of WAS enhanced the flocculation of the EPS by promoting its production.
-
copper ii adsorption by the extracellular polymeric substance extracted from waste activated sludge after short time Aerobic Digestion
Environmental Science and Pollution Research, 2014Co-Authors: Yun Zhou, Jiao ZhangAbstract:The extracellular polymeric substance (EPS) extracted from waste activated sludge (WAS) after short-time Aerobic Digestion was investigated to be used as a novel biosorbent for Cu2+ removal from water. The EPS consisted of protein (52.6 %, w/w), polysaccharide (30.7 %, w/w), and nucleic acid (16.7 %, w/w). Short-time Aerobic Digestion process of WAS for about 4 h promoted the productivity growth of the EPS for about 10 %. With a molecular weight of about 1.9 × 106 Da, the EPS showed a linear structure with long chains, and contained carboxyl, hydroxyl, and amino groups. The sorption kinetics was well fit for the pseudo-second-order model, and the maximum sorption capacity of the EPS (700.3 mg Cu2+/g EPS) was markedly greater than those of the reported biosorbents. Both Langmuir model and Freundlich model commendably described the sorption isotherm. The Gibbs free energy analysis of the adsorption showed that the sorption process was feasible and spontaneous. According to the complex results of multiple analytical techniques, including scanning electron microscopy, Fourier transform infrared spectroscopy, atomic force microscopy, etc., the adsorption process took place via both physical and chemical sorption, but the electrostatic interaction between sorption sites with the functional groups and Cu2+ is the major mechanism.
Siqing Xia - One of the best experts on this subject based on the ideXlab platform.
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Enhancement mechanisms of short-time Aerobic Digestion for waste activated sludge in the presence of cocoamidopropyl betaine.
Scientific reports, 2017Co-Authors: Siqing Xia, Yun Zhou, Everett Eustance, Zhiqiang ZhangAbstract:Cocoamidopropyl betaine (CAPB), which is a biodegradable ampholytic surfactant, has recently been found to dramatically enhance the Aerobic Digestion of waste activated sludge (WAS) in short-time Aerobic Digestion (STAD) systems. Therefore, it is important to understand the mechanisms in which CAPB enhances WAS Aerobic Digestion performance. Results showed that CAPB could dramatically enhance the solubilization of soluble proteins (PN), polysaccharides (PS), nucleic acids (NA) and humic-like substances (HS) in the STAD system within the initial 2 h. Then PN, PS and NA gradually decreased, while HS showed only minor decease. In addition, CAPB increased the proportion of low MW fractions (
-
enhancement mechanisms of short time Aerobic Digestion for waste activated sludge in the presence of cocoamidopropyl betaine
Scientific Reports, 2017Co-Authors: Siqing Xia, Yun Zhou, Everett Eustance, Zhiqiang ZhangAbstract:Cocoamidopropyl betaine (CAPB), which is a biodegradable ampholytic surfactant, has recently been found to dramatically enhance the Aerobic Digestion of waste activated sludge (WAS) in short-time Aerobic Digestion (STAD) systems. Therefore, it is important to understand the mechanisms in which CAPB enhances WAS Aerobic Digestion performance. Results showed that CAPB could dramatically enhance the solubilization of soluble proteins (PN), polysaccharides (PS), nucleic acids (NA) and humic-like substances (HS) in the STAD system within the initial 2 h. Then PN, PS and NA gradually decreased, while HS showed only minor decease. In addition, CAPB increased the proportion of low MW fractions (<20 kDa) from 4.22% to 39.4%, which are more biodegradable. Specific oxygen uptake rates and dehydrogenase enzyme activity results indicated that CAPB markedly improved the Aerobic microorganism activities. Microbial community analyses and principle coordinate analyses (PCoA) revealed that CAPB increased the proportion of some functional microorganisms, including Proteobacteria, Planctomycetales, Acinetobacter, Pseudomonas and Aeromonas. The changes driven by CAPB could explain the enhanced performance of the STAD system for WAS Aerobic treatment.
-
Enhanced performance of short-time Aerobic Digestion for waste activated sludge under the presence of cocoamidopropyl betaine
Chemical Engineering Journal, 2017Co-Authors: Yun Zhou, Jiao Zhang, Zhiqiang Zhang, Chen Zhou, Yenjung Sean Lai, Siqing XiaAbstract:Abstract Short-time Aerobic Digestion (STAD) is a promising technique for waste activated sludge (WAS) stabilization. As a widely used surfactant, cocoamidopropyl betaine (CAPB) could enter wastewater treatment system and influence the WAS properties. It is of big significance to ascertain its influences on the STAD of WAS. CAPB was found to promote the fast removal of organics in WAS. Within 24 h, the removal rate of VSS was up to 28.3%, while no more than 20% was reported in previous studies. The biodegradation rate constants of both VSS and TCOD were increased over 65%. Due to special features of surfactant, CAPB aroused rapid releases of SCOD, PO 4 3 - -P , NH 4 + -N and TN within 2 h, and then their values gradually decreased under the Aerobic Digestion. CAPB was also biodegraded by the system, and the removal rate at 24 h was 91.2%. The biodegradation route contained extracellular adsorption/desorption and Aerobic biodegradation. Biodegradable CAPB could lead to a promising performance of the STAD process for WAS and resulted in zero waste discharge from the treatment system.
Slawomir W Hermanowicz - One of the best experts on this subject based on the ideXlab platform.
-
effects of short time Aerobic Digestion on extracellular polymeric substances and sludge features of waste activated sludge
Chemical Engineering Journal, 2016Co-Authors: Zhiqiang Zhang, Yun Zhou, Jiao Zhang, Slawomir W HermanowiczAbstract:Abstract Aerobic Digestion is an important stabilization process for waste activated sludge. However, extended Aerobic Digestion consumes substantial oxygen and increases the running cost (oxygen demand and sludge production) and CO 2 emission. To tackle these issues, this study investigated the effects of short-time Aerobic Digestion (STAD) on microbial extracellular polymeric substances (EPS), sludge features, and their correlations. The levels of proteins and polysaccharides in EPS consistently increased as the Aerobic Digestion time increased. Nucleic acid in EPS increased only within the first 4 h and then decreased. With an extended Digestion time, sludge floc size (Dv50) increased by 4.67%, and the sludge volume index (SVI) increased by 5.06%, indicative of a deteriorating settleability. The sludge after STAD exhibited better flocculability and dewaterability than that after the prolonged Aerobic Digestion. Proteins and polysaccharides in the EPS significantly correlated with Dv50 ( R 2 = 0.97, P = 0.00 and R 2 = 0.92, P = 0.00, respectively), SVI ( R 2 = 0.88, P = 0.00 and R 2 = 0.93, P = 0.00, respectively), effluent suspended solids (ESS, R 2 = 0.68, P = 0.01 and R 2 = 0.82, P = 0.00, respectively) and the normalized capillary suction time (CST, R 2 = 0.66, P = 0.01 and R 2 = 0.78, P = 0.00, respectively). No significant correlation was found between nucleic acid and these sludge features. These results indicated that proteins and polysaccharides in EPS may govern sludge floc size, settleability, flocculability and dewaterability. Interestingly, good sludge flocculability and dewaterability were observed when the proteins and polysaccharides in EPS were lower than 21.55 and 12.27 mg/g VSS, respectively.
