[Composition of NOM in raw water of Danjiangkou Reservoir of South-to-North Water Diversion Project and comparison of efficacy of enhanced coagulation].

The best enhanced coagulation conditions for the raw water of Danjiangkou Reservoir of South-to-North Water Diversion Project and the molecular weights as well as hydrophobicity composition of Natural organic matter (NOM) in the water were investigated in this study. The results showed that the NOM in the raw water of Danjiangkou Reservoir of South-to-North Water Diversion Project was mainly composed of the fraction with a molecular weight of < 1 000 and transphilic components. Dissolved organic carbon (DOC, 39.98%) and UV254 (39.10%) were the major components. And the fraction with a molecular weight of < 1 000 had the highest contents of THMFP and N-DBPFP. In the raw water of Danjiangkou Reservoir, the sum of transphilic and hydrophobic fractions was up to 80%, and the hydrophobic fraction was the minimum contributor of the NOM, but the THMFP of the hydrophobic fraction had the highest percentage. And when the raw water of Danjiangkou Reservoir was treated using polymeric ferric sulfate (PFS, 4 mg x L(-1)) and poly-acrylamide (PAM, 0.4 mg x L(-1)) , the optimal removal rates of turbidity, DOC, UV254 and THMFP were 76.33%, 25.57%, 37.78% and 23.16%, respectively. The results of this paper can provide theoretical and technological basis for upgrading of the process and operation optimization of original drinking water treatment plants in the intake area of South-to-North Water Diversion Project.

[Effects of different pre-oxidants on DBPs formation potential by chlorination and chloramination of Yangtze River raw water].

Yangtze River raw water from Yangshupu Water Plant, Shanghai was studied in this paper for reduced formation potential of chlorination and chloramination disinfection by-products (DBPs) after pre-oxidation by three kinds of common pre-oxidants, whiich were potassium permanganate, chlorine and chlorine dioxide. Results of chlorination showed that removal effectiveness of all the selected oxidants on total chlorination DBPs was not significant, and the reduction percentages by ClO2, Cl2 and KMnO4 were 8.4%, 5.7% and 3.9%, respectively. The order of DBPs control effect was ClO2, > Cl2 > KMnO4. As to Yangtze River raw water in case of chlorine disinfection, using ClO2 as pre-oxidation agent showed relatively better effect on removal of DBPs. However, chloramination results demonstrated that impacts of the three preoxidants on DBPs formation potential were quite different, and the reduction percentages by ClO2 and KMnO4 were 18.1% and 4.1%, respectively, while pre-chlorination increased the potential by 12.3%. These results revealed that ClO2 had the highest removal effectiveness, meanwhile pre-chlorination should be avoided due to its notable increase in DBPs formation.