Research on phosphorus removal efficiency improvement control technology of sewage treatment plant based on phosphorus storage capacity
A detection method for sludge phosphorus storage capacity was firstly established to address the problems of inaccurate characterization of the phosphorus removal capability of sewage treatment plant return sludge and low efficiency of phosphorus removal agents.The effects of phosphorus removal agent types and dosages on sludge phosphorus storage capacity were investigated,and how to improve the efficiency of phosphorus removal agents was conducted.The results showed that the return sludge of sewage treatment plant using chemical phosphorus removal process had varying degrees of phosphorus removal efficiency,namely"phosphorus storage capacity".Through on-site measurement and fitting calculation,the sludge phosphorus storage capacity was determined to be 0.32-3.25 mg/g(calculated by the removal of soluble reactive phosphorus(sRP)per unit of sludge mixed liquor suspended solids),converting into the dosage of phosphorus removal agents was 0-15.85 mg/L.The type and dosage of residual phosphorus removal agent were key factors affecting the sludge phosphorus storage capacity.At the same addition amount,aluminum sulfate could achieved higher sludge phosphorus capacity than PAC.The pre-hydrolysis degree of the agent was the main reason for the difference in phosphorus storage capacity,and the phosphorus storage capacity of the sludge was positively correlated with the dosage of the phosphorus removal agent.Based on the detection results of sludge phosphorus storage capacity,the sewage treatment plant could improve the efficiency of phosphorus removal agent usage by changing the external sludge return ratio or returning the remaining sludge to the primary settling tank,which could decrease the influent sRP by more than 10％.In addition,returning the remaining sludge to the primary settling tank could reduce sludge emissions by 30％,which not only enhanced the phosphorus removal effect but also achieved sludge reduction,providing important guidance for the green development of sewage treatment plants.
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