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Dongsheng Wang - One of the best experts on this subject based on the ideXlab platform.

  • enhanced technology based for sewage sludge deep dewatering a critical review
    Water Research, 2021
    Co-Authors: Bingdi Cao, Weijun Zhang, Tao Zhang, Dongsheng Wang
    Abstract:

    Sludge is an inevitable by product of sewage treatment, and it includes pathogens, heavy metals, organic pollutants and other toxic substances. The components of sludge are complex and variable with extracellular polymeric substances (EPS) being one. EPS are highly hydrophilic and compressible, and make sludge dewatering difficult. Therefore, the development of efficient sludge-dewatering technology is an important means of mitigating rapid sludge growth. At present, the main methods used for sludge deep-dewatering technology are Chemical preConditioning with high-pressure filtration and electrical mechanical dewatering. The selection of Chemical preConditioning directly determines the final efficiency of the sludge-dewatering process. In this paper, we conduct a comprehensive review of the problems related to sludge dewatering and systematically summarise the impact of different Chemical Conditioning technologies on the efficiency of sludge dewatering. Furthermore, the characteristics of different enhanced dewatering technologies are evaluated and analysed for their adaptability and final disposal methods. We believe that this review can clarify the Chemical conditioner mechanism to improve sludge dewatering, provide reference debugging information for the sludge-dewatering process and promote the development of efficient and environmentally friendly sludge-dewatering technology.

  • relationship between the physicoChemical properties of sludge based carbons and the adsorption capacity of dissolved organic matter in advanced wastewater treatment effects of Chemical Conditioning
    Chemosphere, 2020
    Co-Authors: Weijun Zhang, Dongsheng Wang, Sainan Peng, Tianyi Dong, Yun Deng, Yanping Cui
    Abstract:

    Abstract Pyrolysis carbonisation is a promising technology to convert organic waste into valuable carbon-based materials. However, sludge is generally highly compressible and difficult to dewater because of its high concentrations of biopolymers; the bound water of sludge is trapped in a network composed of biopolymers. Therefore, Chemical Conditioning is an indispensable step for improving sludge dewaterability performance. In the present work, the effects of different Chemical Conditioning agents (polymeric aluminium chloride (PACl), iron(III) chloride (FeCl3), KMnO4–Fe(II) and Fenton’s reagent) on the physicoChemical properties of sludge-based carbons (SBCs) were systematically studied and the SBCs were further used in advanced wastewater treatment. The adsorption mechanisms of dissolved organic matters (DOMs) by different SBCs were also investigated. The results showed that Conditioning with KMnO4–Fe(II) and Fenton’s reagent improved the specific surface area of the SBCs, whereas inorganic salt flocculation Conditioning reduced the porosity of the SBCs. In addition, we found that the Fenton-SBC and Mn/Fe-SBC performed better than the other investigated SBCs in the removal of organic compounds from secondary effluent and that the pseudo-second-order kinetic model could better describe the process of DOMs adsorption by all of the investigated SBCs. Moreover, three-dimensional fluorescence excitation–emission matrix spectroscopy in combination with an analysis of the physical and Chemical fractionation of DOMs showed that all of the SBCs performed well in the adsorption of aromatic substances, hydrophobic acids and hydrophobic neutrals, whereas the Mn/Fe-SBC and Fenton-SBC performed better than the other SBCs in the removal of weakly hydrophobic acids.

  • flocculation dewatering behavior of waste activated sludge particles under Chemical Conditioning with inorganic polymer flocculant effects of typical sludge properties
    Chemosphere, 2019
    Co-Authors: Peng Yang, Weijun Zhang, Ning Wang, Zhaoyi Yang, Dongsheng Wang
    Abstract:

    The effects of typical sludge properties (solids concentration, soluble extracellular polymeric substances (SEPS) and alkalinity) on waste activated sludge flocculation-dewatering behavior and mechanisms under Chemical Conditioning with inorganic polymer flocculant-polyaluminum chloride (PACl) were systematically examined in this study. The results indicated that increasing the solids concentration was conductive to sludge dewatering and could greatly decrease the PACl demand in Chemical Conditioning. Solids concentration had important effects on properties of sludge floc flocculated with PACl, floc structure was more compact and of low EPS concentration at high solids concentrations. High levels of SEPS were adverse to sludge dewaterability after flocculation with PACl, since the SEPS could interact with hydroxy-aluminium through complexation and increase the demand of coagulants. In addition, advantageous speciations of hydroxy-aluminium were rapidly converted into amorphous hydroxides with low flocculation activity at high alkalinity, so the sludge Conditioning efficiency was greatly declined. At the same time, the dominant mechanism of Chemical Conditioning was changed from charge neutralization to sweep coagulation. Finally, this study provides control strategies at complex sludge properties for improving the effectiveness of PACl as a Chemical conditioner.

  • preparation of biological activated carbon bac using aluminum salts conditioned sludge cake for the bio refractory organic contaminants removal from anaerobically digested liquor
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019
    Co-Authors: Haowan Cheng, Dongsheng Wang, Weijun Zhang
    Abstract:

    Abstract Waste sludge management continues to pose a great challenge with the increasing development of municipal wastewater treatment. Preparation of biological activated carbon (BAC) with waste activated sludge (WAS) is a promising method which could realize the synchronous harmlessness and recycling of WAS. The Chemical Conditioning is an indispensable step during the high-pressure dewatering process, which may greatly affect the physicoChemical properties of BAC and adsorptive performance for various contaminants. In this work, sludge cake conditioned with typical inorganic polymeric flocculants – polymeric aluminum chloride (PAC) was used to prepare BAC for anaerobically digested liquor (ADL) treatment, and the effects of hydroxyl aluminum on physicoChemical properties and adsorptive performance were systematically investigated. The results indicated that hydroxyl aluminum speciation had important effects on pore structure and functional groups on the surface of BAC. In comparison with sludge activated carbon, BAC conditioned with PAC exhibited better thermal stability and contained more functional groups. Furthermore, BAC conditioned with PAC of alkalisation degrees of 0.5 and 1.5 (PAC0.5-BAC and PAC1.5-BAC) had remarkable mesoporous structure and notable adsorption capacities for organic contaminants, and the organic contaminants removal could be fitted Freundlich model better. In addition, PAC1.5-BAC performed best in removing chroma and biopolymers (humic and protein-like substances) in filtrate. In brief, this paper proposed a novel sludge carbonization process by coupling enhanced dewatering with catalytic pyrolysis to prepare efficient BAC for wastewater treatment.

  • advanced anaerobic digested sludge dewaterability enhancement using sludge based activated carbon sbac in combination with organic polymers
    Chemical Engineering Journal, 2018
    Co-Authors: Peng Yang, Weijun Zhang, Ning Wang, Bingdi Cao, Fengguo Cui, Dongsheng Wang
    Abstract:

    Abstract Wastewater sludge is difficult to dewater because the extracellular polymeric substances (EPS) it contains are highly hydrated and sticky. Anaerobic digestion generally results in further deterioration of sludge dewaterability due to the release of large quantities of biopolymers and fine particles. Chemical Conditioning is required prior to mechanical dewatering and is of great importance in the operation of the dewatering process. In this work, a novel anaerobically digested (AD) sludge Conditioning process that combines sludge based activated carbon (SBAC) as a skeleton builder with organic polymers (cationic polyacrylamide, CPAM, and chitosan, CTS) for flocculation is proposed to simultaneously remove soluble biopolymers and improve sludge dewaterability. Results indicate that the specific resistance to filtration (SRF) of AD sludge was decreased and that tryptophan-like proteins and humic substances in soluble EPS and loosely-bound EPS were effectively removed by SBAC adsorption through hydrophobic interaction. Flocs formed through CTS Conditioning were smaller but aggregated more strongly and formed less compressible cake than those formed through CPAM Conditioning. SBAC and cationic organic polymers showed a significant synergistic effect in improving sludge dewatering. The incorporation of SBAC into Conditioning with organic polymers increased the strength of sludge floc aggregation and improved recover ability from mechanical shearing. Confocal laser scanning microscopy showed that Conditioning with SBAC in combination with organic polymers resulted in protein molecules forming large aggregates, while polysaccharide molecules were uniformly distributed in sludge floc. This work provides a green and promising strategy for improved AD biosolid dewatering using sludge based activated carbon in combination with CTS.

Weijun Zhang - One of the best experts on this subject based on the ideXlab platform.

  • enhanced technology based for sewage sludge deep dewatering a critical review
    Water Research, 2021
    Co-Authors: Bingdi Cao, Weijun Zhang, Tao Zhang, Dongsheng Wang
    Abstract:

    Sludge is an inevitable by product of sewage treatment, and it includes pathogens, heavy metals, organic pollutants and other toxic substances. The components of sludge are complex and variable with extracellular polymeric substances (EPS) being one. EPS are highly hydrophilic and compressible, and make sludge dewatering difficult. Therefore, the development of efficient sludge-dewatering technology is an important means of mitigating rapid sludge growth. At present, the main methods used for sludge deep-dewatering technology are Chemical preConditioning with high-pressure filtration and electrical mechanical dewatering. The selection of Chemical preConditioning directly determines the final efficiency of the sludge-dewatering process. In this paper, we conduct a comprehensive review of the problems related to sludge dewatering and systematically summarise the impact of different Chemical Conditioning technologies on the efficiency of sludge dewatering. Furthermore, the characteristics of different enhanced dewatering technologies are evaluated and analysed for their adaptability and final disposal methods. We believe that this review can clarify the Chemical conditioner mechanism to improve sludge dewatering, provide reference debugging information for the sludge-dewatering process and promote the development of efficient and environmentally friendly sludge-dewatering technology.

  • relationship between the physicoChemical properties of sludge based carbons and the adsorption capacity of dissolved organic matter in advanced wastewater treatment effects of Chemical Conditioning
    Chemosphere, 2020
    Co-Authors: Weijun Zhang, Dongsheng Wang, Sainan Peng, Tianyi Dong, Yun Deng, Yanping Cui
    Abstract:

    Abstract Pyrolysis carbonisation is a promising technology to convert organic waste into valuable carbon-based materials. However, sludge is generally highly compressible and difficult to dewater because of its high concentrations of biopolymers; the bound water of sludge is trapped in a network composed of biopolymers. Therefore, Chemical Conditioning is an indispensable step for improving sludge dewaterability performance. In the present work, the effects of different Chemical Conditioning agents (polymeric aluminium chloride (PACl), iron(III) chloride (FeCl3), KMnO4–Fe(II) and Fenton’s reagent) on the physicoChemical properties of sludge-based carbons (SBCs) were systematically studied and the SBCs were further used in advanced wastewater treatment. The adsorption mechanisms of dissolved organic matters (DOMs) by different SBCs were also investigated. The results showed that Conditioning with KMnO4–Fe(II) and Fenton’s reagent improved the specific surface area of the SBCs, whereas inorganic salt flocculation Conditioning reduced the porosity of the SBCs. In addition, we found that the Fenton-SBC and Mn/Fe-SBC performed better than the other investigated SBCs in the removal of organic compounds from secondary effluent and that the pseudo-second-order kinetic model could better describe the process of DOMs adsorption by all of the investigated SBCs. Moreover, three-dimensional fluorescence excitation–emission matrix spectroscopy in combination with an analysis of the physical and Chemical fractionation of DOMs showed that all of the SBCs performed well in the adsorption of aromatic substances, hydrophobic acids and hydrophobic neutrals, whereas the Mn/Fe-SBC and Fenton-SBC performed better than the other SBCs in the removal of weakly hydrophobic acids.

  • flocculation dewatering behavior of waste activated sludge particles under Chemical Conditioning with inorganic polymer flocculant effects of typical sludge properties
    Chemosphere, 2019
    Co-Authors: Peng Yang, Weijun Zhang, Ning Wang, Zhaoyi Yang, Dongsheng Wang
    Abstract:

    The effects of typical sludge properties (solids concentration, soluble extracellular polymeric substances (SEPS) and alkalinity) on waste activated sludge flocculation-dewatering behavior and mechanisms under Chemical Conditioning with inorganic polymer flocculant-polyaluminum chloride (PACl) were systematically examined in this study. The results indicated that increasing the solids concentration was conductive to sludge dewatering and could greatly decrease the PACl demand in Chemical Conditioning. Solids concentration had important effects on properties of sludge floc flocculated with PACl, floc structure was more compact and of low EPS concentration at high solids concentrations. High levels of SEPS were adverse to sludge dewaterability after flocculation with PACl, since the SEPS could interact with hydroxy-aluminium through complexation and increase the demand of coagulants. In addition, advantageous speciations of hydroxy-aluminium were rapidly converted into amorphous hydroxides with low flocculation activity at high alkalinity, so the sludge Conditioning efficiency was greatly declined. At the same time, the dominant mechanism of Chemical Conditioning was changed from charge neutralization to sweep coagulation. Finally, this study provides control strategies at complex sludge properties for improving the effectiveness of PACl as a Chemical conditioner.

  • preparation of biological activated carbon bac using aluminum salts conditioned sludge cake for the bio refractory organic contaminants removal from anaerobically digested liquor
    Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019
    Co-Authors: Haowan Cheng, Dongsheng Wang, Weijun Zhang
    Abstract:

    Abstract Waste sludge management continues to pose a great challenge with the increasing development of municipal wastewater treatment. Preparation of biological activated carbon (BAC) with waste activated sludge (WAS) is a promising method which could realize the synchronous harmlessness and recycling of WAS. The Chemical Conditioning is an indispensable step during the high-pressure dewatering process, which may greatly affect the physicoChemical properties of BAC and adsorptive performance for various contaminants. In this work, sludge cake conditioned with typical inorganic polymeric flocculants – polymeric aluminum chloride (PAC) was used to prepare BAC for anaerobically digested liquor (ADL) treatment, and the effects of hydroxyl aluminum on physicoChemical properties and adsorptive performance were systematically investigated. The results indicated that hydroxyl aluminum speciation had important effects on pore structure and functional groups on the surface of BAC. In comparison with sludge activated carbon, BAC conditioned with PAC exhibited better thermal stability and contained more functional groups. Furthermore, BAC conditioned with PAC of alkalisation degrees of 0.5 and 1.5 (PAC0.5-BAC and PAC1.5-BAC) had remarkable mesoporous structure and notable adsorption capacities for organic contaminants, and the organic contaminants removal could be fitted Freundlich model better. In addition, PAC1.5-BAC performed best in removing chroma and biopolymers (humic and protein-like substances) in filtrate. In brief, this paper proposed a novel sludge carbonization process by coupling enhanced dewatering with catalytic pyrolysis to prepare efficient BAC for wastewater treatment.

  • advanced anaerobic digested sludge dewaterability enhancement using sludge based activated carbon sbac in combination with organic polymers
    Chemical Engineering Journal, 2018
    Co-Authors: Peng Yang, Weijun Zhang, Ning Wang, Bingdi Cao, Fengguo Cui, Dongsheng Wang
    Abstract:

    Abstract Wastewater sludge is difficult to dewater because the extracellular polymeric substances (EPS) it contains are highly hydrated and sticky. Anaerobic digestion generally results in further deterioration of sludge dewaterability due to the release of large quantities of biopolymers and fine particles. Chemical Conditioning is required prior to mechanical dewatering and is of great importance in the operation of the dewatering process. In this work, a novel anaerobically digested (AD) sludge Conditioning process that combines sludge based activated carbon (SBAC) as a skeleton builder with organic polymers (cationic polyacrylamide, CPAM, and chitosan, CTS) for flocculation is proposed to simultaneously remove soluble biopolymers and improve sludge dewaterability. Results indicate that the specific resistance to filtration (SRF) of AD sludge was decreased and that tryptophan-like proteins and humic substances in soluble EPS and loosely-bound EPS were effectively removed by SBAC adsorption through hydrophobic interaction. Flocs formed through CTS Conditioning were smaller but aggregated more strongly and formed less compressible cake than those formed through CPAM Conditioning. SBAC and cationic organic polymers showed a significant synergistic effect in improving sludge dewatering. The incorporation of SBAC into Conditioning with organic polymers increased the strength of sludge floc aggregation and improved recover ability from mechanical shearing. Confocal laser scanning microscopy showed that Conditioning with SBAC in combination with organic polymers resulted in protein molecules forming large aggregates, while polysaccharide molecules were uniformly distributed in sludge floc. This work provides a green and promising strategy for improved AD biosolid dewatering using sludge based activated carbon in combination with CTS.

Gary L Amy - One of the best experts on this subject based on the ideXlab platform.

  • compositional similarities and differences between transparent exopolymer particles tep from two marine bacteria and two marine algae significance to surface biofouling
    Marine Chemistry, 2015
    Co-Authors: H. Winters, Y. Ekowati, M D Kennedy, Loreen O Villacorte, Abdul-hamid Emwas, Gary L Amy
    Abstract:

    Abstract Transparent-exopolymer-particles (TEPs) have been recently identified as a significant contributor to surface biofouling, such as on reverse osmosis (RO) membranes. TEP research has mainly focused on algal TEP/TEP precursors while limited investigations have been conducted on those released by bacteria. In this study, TEP/TEP precursors derived from both algae and bacteria were isolated and then characterized to investigate their similarities and/or differences using various advanced analytical techniques, thus providing a better understanding of their potential effect on biofouling. Bacterial TEP/TEP precursors were isolated from two species of marine bacteria (Pseudidiomarina homiensis and Pseudoalteromonas atlantica) while algal TEP/TEP precursors were isolated from two marine algae species (Alexandrium tamarense and Chaetoceros affinis). Results indicated that both isolated bacterial and algal TEP/TEP precursors were associated with protein-like materials, and most TEP precursors were high-molecular-weight biopolymers. Furthermore all investigated algal and bacterial TEP/TEP precursors showed a lectin-like property, which can enable them to act as a Chemical Conditioning layer and to agglutinate bacteria. This property may enhance surface biofouling. However, both proton nuclear magnetic resonance (NMR) spectra and the nitrogen/carbon (N/C) ratios suggested that the algal TEP/TEP precursors contained much less protein content than the bacterial TEP/TEP precursors. This difference may influence their initial deposition and further development of surface biofouling.

  • Compositional similarities and differences between transparent exopolymer particles (TEPs) from two marine bacteria and two marine algae: Significance to surface biofouling
    Marine Chemistry, 2015
    Co-Authors: Sheng Li, H. Winters, Y. Ekowati, M D Kennedy, Loreen O Villacorte, Abdul-hamid Emwas, Gary L Amy
    Abstract:

    Transparent-exopolymer-particles (TEPs) have been recently identified as a significant contributor to surface biofouling, such as on reverse osmosis (RO) membranes. TEP research has mainly focused on algal TEP/TEP precursors while limited investigations have been conducted on those released by bacteria. In this study, TEP/TEP precursors derived from both algae and bacteria were isolated and then characterized to investigate their similarities and/or differences using various advanced analytical techniques, thus providing a better understanding of their potential effect on biofouling. Bacterial TEP/TEP precursors were isolated from two species of marine bacteria (Pseudidiomarina homiensis and Pseudoalteromonas atlantica) while algal TEP/TEP precursors were isolated from two marine algae species (Alexandrium tamarense and Chaetoceros affinis). Results indicated that both isolated bacterial and algal TEP/TEP precursors were associated with protein-like materials, and most TEP precursors were high-molecular-weight biopolymers. Furthermore all investigated algal and bacterial TEP/TEP precursors showed a lectin-like property, which can enable them to act as a Chemical Conditioning layer and to agglutinate bacteria. This property may enhance surface biofouling. However, both proton nuclear magnetic resonance (NMR) spectra and the nitrogen/carbon (N/C) ratios suggested that the algal TEP/TEP precursors contained much less protein content than the bacterial TEP/TEP precursors. This difference may influence their initial deposition and further development of surface biofouling.

Zhan Chen - One of the best experts on this subject based on the ideXlab platform.

  • improvement of wastewater sludge dewatering performance using titanium salt coagulants tscs in combination with magnetic nano particles significance of titanium speciation
    Water Research, 2017
    Co-Authors: Weijun Zhang, Dongsheng Wang, Bingdi Cao, Zhan Chen, Caixia Wang, Hua Xia
    Abstract:

    In this study, the effects of Chemical Conditioning using titanium salt coagulants (TSCs) of different hydrolysis speciation in combination with magnetic nano-particles on dewatering performance of waste activated sludge were evaluated by means of specific resistance to filtration (SRF) and capillary suction time (CST). The morphological and extracellular polymeric substances (EPS) properties under Chemical Conditioning were investigated in detail to understand the reaction mechanisms involved. The results showed that the TSC with basicity of 0.5 performed better in improving sludge dewatering performance than other TSCs. Sludge floc formed by TSC0.5 treatment was characterized by larger floc size and higher floc strength than that conditioned by other TSCs. EPS compression and densification were the major mechanisms of sludge Conditioning, and TSC0.5 had better performance in compressing EPS structure. In addition, reduction of soluble EPS concentration, especially protein-like substances contributed to improvement of sludge filterability under Conditioning. Furthermore, addition of Fe2O3 nanoparticles could further improve dewatering performance and decrease compressibility of sludge system by acting as skeleton builders and enhancing floc strength. The sludge particles aggregation efficiency was effectively improved with addition of nano-Fe2O3. They also were able to bind with protein-like substance in EPS component, which might contribute to promotion of sludge filterability.

  • insights into the respective role of acidification and oxidation for enhancing anaerobic digested sludge dewatering performance with fenton process
    Bioresource Technology, 2015
    Co-Authors: Weijun Zhang, Peng Yang, Zhan Chen, Xiaoyin Yang, Dongsheng Wang
    Abstract:

    Digested sludges generally exhibit poorer dewaterability than activated sludges. This study investigated the effects of acidification and oxidation on EPS properties and dewaterability of anaerobic digested sludge in Fenton treatment in order to unravel the underlying mechanism of sludge Conditioning. The results indicated that sludge dewatering property was improved after acidification treatment. Meanwhile, fluorescence analysis revealed that the protein-like substances were effectively removed from sludge bulk after acidification treatment. Acidification and Fenton oxidation showed a significant synergetic effect in enhancing sludge dewatering process. Solubilization and decomposition of bound EPS occurred synchronously during Fenton Conditioning. Oxidation process is very likely to play a more important role in sludge Conditioning than Fenton coagulation. According to pilot test, Fenton treatment performed much better in cake moisture content reduction than Chemical Conditioning with traditional inorganic coagulants. Additionally, full-scale application of Fenton Conditioning will not have detrimental effects on performance of wastewater treatment system.

Bingdi Cao - One of the best experts on this subject based on the ideXlab platform.

  • enhanced technology based for sewage sludge deep dewatering a critical review
    Water Research, 2021
    Co-Authors: Bingdi Cao, Weijun Zhang, Tao Zhang, Dongsheng Wang
    Abstract:

    Sludge is an inevitable by product of sewage treatment, and it includes pathogens, heavy metals, organic pollutants and other toxic substances. The components of sludge are complex and variable with extracellular polymeric substances (EPS) being one. EPS are highly hydrophilic and compressible, and make sludge dewatering difficult. Therefore, the development of efficient sludge-dewatering technology is an important means of mitigating rapid sludge growth. At present, the main methods used for sludge deep-dewatering technology are Chemical preConditioning with high-pressure filtration and electrical mechanical dewatering. The selection of Chemical preConditioning directly determines the final efficiency of the sludge-dewatering process. In this paper, we conduct a comprehensive review of the problems related to sludge dewatering and systematically summarise the impact of different Chemical Conditioning technologies on the efficiency of sludge dewatering. Furthermore, the characteristics of different enhanced dewatering technologies are evaluated and analysed for their adaptability and final disposal methods. We believe that this review can clarify the Chemical conditioner mechanism to improve sludge dewatering, provide reference debugging information for the sludge-dewatering process and promote the development of efficient and environmentally friendly sludge-dewatering technology.

  • advanced anaerobic digested sludge dewaterability enhancement using sludge based activated carbon sbac in combination with organic polymers
    Chemical Engineering Journal, 2018
    Co-Authors: Peng Yang, Weijun Zhang, Ning Wang, Bingdi Cao, Fengguo Cui, Dongsheng Wang
    Abstract:

    Abstract Wastewater sludge is difficult to dewater because the extracellular polymeric substances (EPS) it contains are highly hydrated and sticky. Anaerobic digestion generally results in further deterioration of sludge dewaterability due to the release of large quantities of biopolymers and fine particles. Chemical Conditioning is required prior to mechanical dewatering and is of great importance in the operation of the dewatering process. In this work, a novel anaerobically digested (AD) sludge Conditioning process that combines sludge based activated carbon (SBAC) as a skeleton builder with organic polymers (cationic polyacrylamide, CPAM, and chitosan, CTS) for flocculation is proposed to simultaneously remove soluble biopolymers and improve sludge dewaterability. Results indicate that the specific resistance to filtration (SRF) of AD sludge was decreased and that tryptophan-like proteins and humic substances in soluble EPS and loosely-bound EPS were effectively removed by SBAC adsorption through hydrophobic interaction. Flocs formed through CTS Conditioning were smaller but aggregated more strongly and formed less compressible cake than those formed through CPAM Conditioning. SBAC and cationic organic polymers showed a significant synergistic effect in improving sludge dewatering. The incorporation of SBAC into Conditioning with organic polymers increased the strength of sludge floc aggregation and improved recover ability from mechanical shearing. Confocal laser scanning microscopy showed that Conditioning with SBAC in combination with organic polymers resulted in protein molecules forming large aggregates, while polysaccharide molecules were uniformly distributed in sludge floc. This work provides a green and promising strategy for improved AD biosolid dewatering using sludge based activated carbon in combination with CTS.

  • improvement of wastewater sludge dewatering performance using titanium salt coagulants tscs in combination with magnetic nano particles significance of titanium speciation
    Water Research, 2017
    Co-Authors: Weijun Zhang, Dongsheng Wang, Bingdi Cao, Zhan Chen, Caixia Wang, Hua Xia
    Abstract:

    In this study, the effects of Chemical Conditioning using titanium salt coagulants (TSCs) of different hydrolysis speciation in combination with magnetic nano-particles on dewatering performance of waste activated sludge were evaluated by means of specific resistance to filtration (SRF) and capillary suction time (CST). The morphological and extracellular polymeric substances (EPS) properties under Chemical Conditioning were investigated in detail to understand the reaction mechanisms involved. The results showed that the TSC with basicity of 0.5 performed better in improving sludge dewatering performance than other TSCs. Sludge floc formed by TSC0.5 treatment was characterized by larger floc size and higher floc strength than that conditioned by other TSCs. EPS compression and densification were the major mechanisms of sludge Conditioning, and TSC0.5 had better performance in compressing EPS structure. In addition, reduction of soluble EPS concentration, especially protein-like substances contributed to improvement of sludge filterability under Conditioning. Furthermore, addition of Fe2O3 nanoparticles could further improve dewatering performance and decrease compressibility of sludge system by acting as skeleton builders and enhancing floc strength. The sludge particles aggregation efficiency was effectively improved with addition of nano-Fe2O3. They also were able to bind with protein-like substance in EPS component, which might contribute to promotion of sludge filterability.

  • variations in distribution and composition of extracellular polymeric substances eps of biological sludge under potassium ferrate Conditioning effects of ph and ferrate dosage
    Biochemical Engineering Journal, 2016
    Co-Authors: Dongsheng Wang, Weijun Zhang, Bingdi Cao
    Abstract:

    Abstract The effect of pH on Chemical Conditioning with potassium ferrate (K2FeO4) for improving sludge filtration dewatering performance has been studied. The variation of extracellular polymeric substances (EPS) in Conditioning process was investigated in detail to unravel the reaction mechanism. The results indicated that sludge dewaterability was improved by decreasing solution pH in terms of filtration rate and cake solids content. At acid conditions, protonation of EPS resulted in reduction of negative charge and densification of sludge floc. Sludge Conditioning efficiency was improved with decrease in pH. Ferrate can solubilize EPS through oxidation process and also remove a portion of soluble EPS (SEPS) by charge neutralization and interfacial adsorption of hydrolyzed ferric ions, consequently compressing EPS and decreasing total extractable EPS content. In addition, when pH and potassium ferrate were 3 and 0.1 g/gTSS, the sludge filtration dewatering rate and extent reached the maximum. Deterioration of sludge dewaterability was observed as the ferrate was overdosed (>0.2 g/gTSS). This could be attributed to the release of a large amount of bound EPS (BEPS) as a result of ferrate oxidation, consequently increasing the sludge filtration resistance.