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Novel Insights into Extracellular Polymeric Substance Degradation, Hydrophilic/Hydrophobic Characteristics, and Dewaterability of Waste Activated Sludge Pretreated by Hydroxylamine Enhanced Fenton Oxidation
https://orcid.org/0000-0003-0858-5587
https://orcid.org/0000-0001-8578-9773
https://orcid.org/0000-0002-6825-3536
Extracellular polymeric substance (EPS) is recognized as a critical component that determines sludge dewaterability. In this study, a layer by layer degradation of EPS was confirmed for the first time by fluorescent staining and confocal laser scanning microscopy in sludge conditioned by hydroxylamine enhanced Fenton oxidation (Fenton-HA). The oxidation capability was elevated by increasing the molar ratio of H2O2:Fe2+ from 2 to 20 which significantly reduced the bound EPS content from 4.9 mg TOC/g dry solid (DS) to 2.9 mg TOC/g DS but deteriorated sludge dewaterability, i.e. increased the capillary suction time from 48.3 to 73.8 s and specific resistance filtration from 4.8 × 1012 to 6.0 × 1012 m/kg in Fenton-HA conditioning. Based on the extended Derjaguin–Landau–Verwey–Overbeek theory, the degradation of surface EPS increased the hydrophilicity of sludge flocs and induced a higher hydration interaction energy and energy barrier, thus resulting in an increased repulsive force among sludge flocs and higher bound water content (r = 0.93, p < 0.05). The increase of hydrophilicity was likely due to the exposure of inner EPS which had higher ratios of hydrophilic functional groups (COH and CO) and hydrophilic amino acids compared with surface EPS. The existence of the relatively higher hydrophobicity of the surface EPS layer would favor the separation of sludge flocs from water, while the degradation of the outer layer of the EPS would result in the exposure of the inner hydrophilic EPS and deteriorate the sludge dewaterability. Hence, this study provided a novel insight into the relationship between the surface EPS degradation and the improvement of dewaterability.
Novel Insights into Extracellular Polymeric Substance Degradation, Hydrophilic/Hydrophobic Characteristics, and Dewaterability of Waste Activated Sludge Pretreated by Hydroxylamine Enhanced Fenton Oxidation
https://orcid.org/0000-0003-0858-5587
https://orcid.org/0000-0001-8578-9773
https://orcid.org/0000-0002-6825-3536
Extracellular polymeric substance (EPS) is recognized as a critical component that determines sludge dewaterability. In this study, a layer by layer degradation of EPS was confirmed for the first time by fluorescent staining and confocal laser scanning microscopy in sludge conditioned by hydroxylamine enhanced Fenton oxidation (Fenton-HA). The oxidation capability was elevated by increasing the molar ratio of H2O2:Fe2+ from 2 to 20 which significantly reduced the bound EPS content from 4.9 mg TOC/g dry solid (DS) to 2.9 mg TOC/g DS but deteriorated sludge dewaterability, i.e. increased the capillary suction time from 48.3 to 73.8 s and specific resistance filtration from 4.8 × 1012 to 6.0 × 1012 m/kg in Fenton-HA conditioning. Based on the extended Derjaguin–Landau–Verwey–Overbeek theory, the degradation of surface EPS increased the hydrophilicity of sludge flocs and induced a higher hydration interaction energy and energy barrier, thus resulting in an increased repulsive force among sludge flocs and higher bound water content (r = 0.93, p < 0.05). The increase of hydrophilicity was likely due to the exposure of inner EPS which had higher ratios of hydrophilic functional groups (COH and CO) and hydrophilic amino acids compared with surface EPS. The existence of the relatively higher hydrophobicity of the surface EPS layer would favor the separation of sludge flocs from water, while the degradation of the outer layer of the EPS would result in the exposure of the inner hydrophilic EPS and deteriorate the sludge dewaterability. Hence, this study provided a novel insight into the relationship between the surface EPS degradation and the improvement of dewaterability.
Novel Insights into Extracellular Polymeric Substance Degradation, Hydrophilic/Hydrophobic Characteristics, and Dewaterability of Waste Activated Sludge Pretreated by Hydroxylamine Enhanced Fenton Oxidation
https://orcid.org/0000-0003-0858-5587
https://orcid.org/0000-0001-8578-9773
https://orcid.org/0000-0002-6825-3536
Extracellular polymeric substance (EPS) is recognized as a critical component that determines sludge dewaterability. In this study, a layer by layer degradation of EPS was confirmed for the first time by fluorescent staining and confocal laser scanning microscopy in sludge conditioned by hydroxylamine enhanced Fenton oxidation (Fenton-HA). The oxidation capability was elevated by increasing the molar ratio of H2O2:Fe2+ from 2 to 20 which significantly reduced the bound EPS content from 4.9 mg TOC/g dry solid (DS) to 2.9 mg TOC/g DS but deteriorated sludge dewaterability, i.e. increased the capillary suction time from 48.3 to 73.8 s and specific resistance filtration from 4.8 × 1012 to 6.0 × 1012 m/kg in Fenton-HA conditioning. Based on the extended Derjaguin–Landau–Verwey–Overbeek theory, the degradation of surface EPS increased the hydrophilicity of sludge flocs and induced a higher hydration interaction energy and energy barrier, thus resulting in an increased repulsive force among sludge flocs and higher bound water content (r = 0.93, p < 0.05). The increase of hydrophilicity was likely due to the exposure of inner EPS which had higher ratios of hydrophilic functional groups (COH and CO) and hydrophilic amino acids compared with surface EPS. The existence of the relatively higher hydrophobicity of the surface EPS layer would favor the separation of sludge flocs from water, while the degradation of the outer layer of the EPS would result in the exposure of the inner hydrophilic EPS and deteriorate the sludge dewaterability. Hence, this study provided a novel insight into the relationship between the surface EPS degradation and the improvement of dewaterability.
Novel Insights into Extracellular Polymeric Substance Degradation, Hydrophilic/Hydrophobic Characteristics, and Dewaterability of Waste Activated Sludge Pretreated by Hydroxylamine Enhanced Fenton Oxidation
Yu, Wenbo (author) / Wen, Qianqian (author) / Yang, Jiakuan (author) / Xiao, Keke (author) / Zhu, Yuwei (author) / Tao, Shuangyi (author) / Liang, Sha (author) / Hu, Shaogang (author) / Wu, Qiongxiang (author) / Hou, Huijie (author)
ACS ES&T Engineering ; 1 ; 385-392
2021-03-12
Article (Journal)
Electronic Resource
English
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