[Effect of coagulation on preventing membrane from fouling].

In this experiment, the effects on improve of flux and prevention of membrane from fouling is studied. The results demonstrate that after backwashing, the flux was completely recovered by addition of 4mg/L and l0mg/L(as Al), while the flux was only 40% of initial flux without coagulation pretreatment. It is also observed that whether or not prevention of fouling by coagulation are depended on the characteristics of cake layer formed on membrane surface during membrane filtration. In the presence of filtration of coagulation floc suspension, coagulation can form cake layer on membrane surface, thus prevent membrane from fouling effectively, while in the presence of filtration of supernatant, fouling are occurred due to cake layer comprising small, neutral, hydrophilic compounds, which can not remove by backwash.