To evaluate the feasibility of hybrid process of coagulation,sedimentation and immersed ultrafiltration(UF) for the drinking water treatment from Bei River source water,pilot study was performed in terms of pollutants removal and membrane fouling.The performance of the hybrid UF process was also compared with that of the conventional process in the full-scale drinking water treatment plant.Results showed that in the conventional treatment process,there was still 0.176 NTU of turbidity in the sand-filtration effluent on average;while it was only 0.080 NTU in the hybrid UF process.The removal efficiencies of conventional treatment process for CODMnand UV254 were 47.5% and 42.3%,respectively,which were slightly lower than the 50.6% and 44.0% achieved by the hybrid UF process.As for the membrane fouling,it was shown that the trans-membrane pressure(PTM) would increase rapidly when direct UF of raw water was carried out.However,in the hybrid UF process,due to the pre-removal of membrane foulants by coagulation and sedimentation,the PTM development rate became much lower;and stable operation of the UF could be achieved.It is demonstrated that the hybrid UF process can improve the security of drinking water supply.