Influence of sludge extracellular polymeric substances on rheology and dewatering in a thermal hydrolysis anaerobic digestion process
To elucidate the impact of extracellular polymeric substances(EPS)on dewatering and rheology in the hydrothermal anaerobic digestion process,sludge from a wastewater treatment plant in Beijing utilizing the hydrothermal anaerobic digestion process was selected as the subject.The study investigated the effects of EPS removal on sludge rheology and solid content by measuring sludge particle size,conducting three-dimensional fluorescence analysis,and analyzing the EPS content in each layer.The results indicated a 66.79％reduction in the particle size of sludge pretreated by thermal hydrolysis compared to that of mixed sludge.The fluorescence peaks of mixed sludge were concentrated in the tyrosine-like protein region and tryptophan-like protein region.After thermal hydrolysis,the fluorescence response values of soluble microbial metabolites increased,followed by an increase in the fluorescence response values of the humic acid region after anaerobic digestion.The removal of EPS significantly influenced sludge flowability and mobility.The apparent viscosity decreased more after EPS removal for both thermal hydrolysis sludge and thermal hydrolyzed anaerobic digested sludge.Additionally,various dewatering methods had distinct effects on the solids content of the sludge.Mixed sludge and thermally hydrolyzed anaerobically digested sludge exhibited respective increases of 366.67％and 148.92％in solids content following the removal of the S-EPS layer.However,the increase in thermal hydrolysis sludge was not as pronounced after the removal of the S-EPS layer.The study results provide insights and a foundation for sludge dewatering concerning sludge components and rheology.
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