Influence of Organic Matters Content in the Eastern Line of South-to-North Water Diversion on Finished Water Quality

The change of organic carbon in the source water since the introduction of the eastern line of the South-to-North Water Diversion in Jiaodong water supply was analyzed. The results showed that the content of organic carbon in the source water had increased significantly with an average of 5 mg/L or more since 2016. The increase of organic carbon in water led to the problems of an unusual odour in finished water, increase of disinfection byproducts concentration and poor biological stability of water quality. In order to understand the removal of assimilable organic carbon (AOC) and the biological stability of water quality of the pipe network, the TOC content,distribution of organic carbon molecular weight and AOC content of different units in a waterworks were analyzed in February 2019. The removal efficiency of TOC by the treatment process of the waterworks was 23.9%, indicating that the TOC content in the finished water was high. The source water of the waterworks was mainly organic carbon with molecular weight less than 0.5 ku and between 3 ku and 5 ku, and the relative contribution of organic carbon with different molecular weight to the total dissolved organic carbon in the effluent of each unit was not significant. The AOC content in source water was 322.36 μg/L, and AOC-P17 accounted for 66.1% of the total AOC. The total removal efficiency of AOC was 46.1%, and the removal efficiency of AOC-P17 was higher than that of AOC-NOX.