Phosphorus deficiency leads to the loosening of activated sludge: The role of exopolysaccharides in aggregation. (March 2022)

• Record Type: Journal Article
• Authors: Yang, Fan; Qu, Jianwei; Huang, Xiaoxiao; Chen, Youpeng; Yan, Peng; Guo, Jinsong; Fang, Fang
• Is Part Of: Chemosphere. Volume 290(2022)
• Publication Date: 2022-03
• Subjects: Activated sludge flocs -- Activated sludge performance -- Extracellular polymers -- Exopolysaccharides -- Microbial community; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2021.133385
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Whether phosphorus deficiency in influent will affect the aggregation and sedimentation of activated sludge needs to be further clarified. This paper systematically studied the structure, aggregation and settlement of activated sludge, and the composition, properties and chemical structure of extracellular polymers and microbial community structure of sludge under different influent phosphorus contents to determine the causes of sludge aggregation and structural deterioration. The results show that phosphorus deficiency in influent leads to a decrease in the aggregation capacity and a loose structure of activated sludge, and the reduction of hydrophobic interactions is the main factor of sludge aggregation and structural deterioration. The content, functional groups and protein secondary structure of extracellular protein were almost unchanged. An increase in the content and hydrophilicity of extracellular polysaccharide (PS) results in a decrease in sludge hydrophobicity. Under phosphorus deficiency, the changes in microbial species related to PS secretion were the reasons for the increase in PS content and hydrophilicity. The negative effects of PS content and hydrophilicity on sludge aggregation and structure are important findings of this work and are expected to be useful for better understanding the restoration of activated sludge performance in the treatment of phosphorus-deficient wastewater. Graphical abstract: Image 1 Highlights: Activated sludge aggregation and structure under phosphorus deficiency was studied. The hydrophobicity affects the aggregation and structure of activated sludge. Exopolysaccharides rather than extracellular protein reduced aggregation of sludge. Exopolysaccharide content and hydrophilicity reduce the hydrophobicity of sludge. Changes in the microbial genera have led to changes in PS content and properties.