Comparative experiments on the inactivation of Copepod were investigated in southern China.The 100% of inactivation effect may be attained by 3.0 mg/L of ozone for contacting time of 25 min,whereas 0.5 mg/L of dosage resulted in only 30% of inactivation rate.Copepod may not be completely inactivated by ozone oxidation for feasible dosage limited by higher bromide in raw water.The favorable environment of granular activated carbon(GAC)filter provided Copepod with conditions for excess propagation.The disinfection experimental results show that the inactivation rate is 90% by 2.0 mg/L of chloramines for contacting time of 30 min,whereas only 70% is attained with chlorine.The GC-MS examination indicates that the total organic substance is increased to 92 species including 13 sorts of halogenated hydrocarbon by chlorine disinfection,which is more than that of chloramines.More products of brominated trihalomethanes occur in treated water by chlorine disinfection and total amount of THMs is 3 times as high as that of chloramines.
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. UV254 was used to measure the organic matter adsorbed by PAC. And the results show that the maximum elimination can be achieved while the dosage of PAC is 60mg/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 20mg/L in this study, and the average removal rate of the PAC/UF process for dissolved organic carbon (DOC), UV254, and CODMn are 42.6%, 63.4%, and 45.7% respectively.
