New insight into filamentous sludge bulking during wastewater treatment: Surface characteristics and thermodynamics

Yu Shen; Dong-Mei Huang; You-Peng Chen; Peng Yan; Xu Gao

doi:10.1016/j.scitotenv.2019.135795

New insight into filamentous sludge bulking during wastewater treatment: Surface characteristics and thermodynamics

Sci Total Environ. 2020 Apr 10:712:135795. doi: 10.1016/j.scitotenv.2019.135795. Epub 2019 Nov 28.

Authors

Yu Shen¹, Dong-Mei Huang¹, You-Peng Chen², Peng Yan³, Xu Gao⁴

Affiliations

¹ National Research Base of Intelligent Manufacturing Service, Chongqing Key Laboratory of Catalysis and New Environmental Materials, Chongqing Technology and Business University, Chongqing 400067, China; Chongqing South-to-Thais Environmental Protection Technology Research Institute Co., Ltd., Chongqing 400067, China.
² Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China.
³ Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China. Electronic address: yanpengstu@163.com.
⁴ National Research Base of Intelligent Manufacturing Service, Chongqing Key Laboratory of Catalysis and New Environmental Materials, Chongqing Technology and Business University, Chongqing 400067, China.

PMID: 31866048
DOI: 10.1016/j.scitotenv.2019.135795

Abstract

Although there have been many studies on filamentary bulking of activated sludge, it has been revealed that there is still a gap in the microscopic mechanism of filamentary bulking. In this study, the surface characteristics and thermodynamics of sludge floc were investigated to reveal the mechanism of filamentous sludge bulking. The results showed that the EPS content gradually decreased from 71.09 mg/g VSS to 40.00 mg/g VSS and the protein (PN) content of the EPS significantly decreased from 64.10 mg/g VSS to 35.85 mg/g VSS during sludge bulking. The variation in the EPS and its components led to a decrease in the relative hydrophobicity of sludge and an increase in surface negative charge; then, deterioration of the flocculation setteability of sludge flocs occurred. The electric double layer (W_R) was the main force determining the aggregation of sludge during sludge bulking. The total energy of the interaction (W_T) increased during sludge bulking, which led to an increase in the difficulty of sludge accumulation. This study is useful for understanding the filamentous bulking of sludge within an activated sludge process.

Keywords: Extracellular polymer substances; Sludge bulking; Surface characteristics; Surface thermodynamics; XDLVO theory.