| Membrane fouling is a key problem limiting membrane bioreactor's wide application. In this study, coagulant is added to the mixed liquor in SMBR in order to enhance the membrane filterability and control membrane fouling. Nine comparative experiments are carried out by adding FeCl3 and PFC. Analyze the variations of EPS content and its effect on SMBR membrane fouling by coagulant addition. Finally, select the optimal coagulant to add into SMBR, and then run the system for a long-term. We can come to the conclusions as follow:The effects of the two coagulants addition on SMBR sewage treatment effect, EPS content and membrane fouling show similar disciplines. Addtion of coagulants can improve SMBR effluent quality to a certain extent. As coagulants dose increases, removal efficiency of TN is slightly improved; appropriate doses of coagulants can enhance removal efficiency of TP. When the dose of coagulant is appropriate, the increasing speed of membrane filtration resistance is slow, sludge forms larger and compacter particles. While excessive doses of coagulants will bring membrane fouling loading directly. The contents of Polysaccharide in EPSs, protein and humic acid in LB have obvious correlations with the rise of the trans-membrane pressure.The content of EPSs with 15mg/L PFC is less than the content of EPSs with 30mg/L FeCl3, and the increasing speed of TMP with 15mg/L PFC is slower than that with 30mg/L FeCl3, so PFC can control the membrane fouling more effectively.In long-term experiment with PFC, when reaching the same transmembrane pressure, PFC-SMBR system run 40 days, while the SMBR without coagulant addition only run 18 days. Analyzing the components of membrane resistanc, it shows that transmembrane pressure increased quickly in late stage because of the gel layer resistance and membrane pore blocking. Thus, operation cycle of SMBR can be prolonged by PFC addition, which can effectively relieve membrane fouling.
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