Determination of the Dose of PAC in Ultrafiltration System for Drinking Water Treatment

Immersed ultrafiltration （UF） process was chosen to treat the raw water of the Yangtze River. In order to control the membrane fouling, powdered activated carbon （PAC） was added to the UF tank for removing natural organic matter （NOM）. The optimal dosage of PAC was investigated in the PAC/UF combined process. UV~4 waS used to measure the organic matter adsorbed by PAC. And the results show that the maximum elimination can be achieved white the dosage of PAC is 60 mg/L. However, the elimination can not reduce the rate of membrane fouling which indicates that the organic matter absorbed by PAC is not the only factor leading to the fouling and the overload of PAC also contributes to the fouling. Therefore, the optimal dosage of PAC should be determined by organic matter removal as well as membrane fouling control. The ultimately optimized dosing of PAC is 20 mg/L in this study, and the average removal rate of the PAC/UF process for dissolved organic carbon （ DOC）, UV254, and CODM. are 42.6 %, 63.4 %, and 45.7 % respectively.