Effect of Cd2+Concentration on Formation of EPS Components in Aerobic Granular Sludge
In order to investigate the impact of heavy metal Cd2+on the functionality of aerobic granular sludge systems,this paper adopted UV and three-dimensional fluorescence spectroscopy to study the effects of varying concentrations of Cd2+on the aggregation and composition of aerobic granular sludge in an SBR reactor.Specifically,the analysis focused on the extracellular polymeric substances(EPS)components,including loosely bound EPS(LB-EPS),soluble EPS(SB-EPS),and tightly bound EPS(TB-EPS).The experimental results demonstrated that low concentrations of Cd2+(less than 0.1 mg/l)enhanced the production of EPS,while high concentrations(greater than 3 mg/1)inhibited its production.As the Cd2+concentration increased,the SB-EPS content gradually decreased,with a notable increase in protein content and a significant decrease in polysaccharides and humic acid.When the Cd2+concentration was below 0.1 mg/L,TB-EPS increased significantly,primarily due to an increase in protein composition.However,when Cd2+concentration exceeded 3 mg/l,the secretion of TB-EPS was suppressed,although the protein content remained higher than in the control group.Polysaccharides and humic acid content decreased significantly.LB-EPS was influenced by numerous factors,resulting in irregular changes in its content.This study utilized the extended DLVO theory to analyze the impact of changes in EPS component content on the settling performance of aerobic granular sludge,aiming to provide robust support for the application of aerobic granulation technology in industrial wastewater treatment.
Aerobic granular sludgeextracellular polymers(EPS)cadmium ions(Cd2+)sludge settling index(SVI)extended DLVO theory
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