A low recovery rate was observed in the treatment of finished water from sedimentation tank with a UF membrane system

and recovery of membrane backwash water can improve productivity and reduce the cost of membrane treatment systems.In this study

two bench-scale coagulation microfiltration membrane systems were installed.The raw water of one membrane system was a blend of water from the pre-treated membrane backwash water and Luan River water in a 1∶9 ratio.Another membrane system was used to treat Luan River water.The aim of this study was to investigate effect of various pre-treatments on the finished water quality and membrane fouling rate.The results showed that the produced water quality from the mixed water system was improved with the addition of PAC in the pre-treatment of membrane backwash water

which was compared to the results obtained by coagulation.The removal rates of UV254 and CODMn were increased by 9% and 6.3%

respectively.There was no difference in turbidity of the produced waters by the various pre-treatments.Moreover

attenuation rate of SF was reduced by 16.6% with adding PAC in the pre-treatment.And the produced water quality from Luan River water system and membrane fouling rate were similar to those in mixed water system when the PAC was added in the pre-treatment.