Treatment of low temperature and low turbidity water enhanced by reusing ultrafiltration membrane washing water

The effects of recycling ultrafiltration(UF) membrane washing water and PAC pre-absorption on the coagulation-UF process were investigated in the treatment of low temperature and low turbidity water. The results show that the reuse of membrane washing water could improve the coagulation efficiency and retard the membrane fouling. There was imperceptible influence on the turbidity and THMs precursors of the membrane effluent, but the average DOC and residual aluminum was obviously decreased to 2.21 mg·L^-1 and 0.081 mg·L^-1, respectively. The Trans-membrane pressure (TMP) test indicated that compared to other combination processes, the TMP of UF coupled with recycling of membrane washing water increased steadily from 0.061 MPa to 0.069 MPa in the 48h operation duration. Meanwhile, PAC pre-absorption was able to improve the water quality and mitigate the membrane fouling to a certain degree.