Molecular weight distributions of effluent organic matters and the biodegradability assessment of a typical advanced drinking water treatment plant in South China

摘要

Biodegradability and molecular weight (MW) distributions of effluent organic matters were studied. Sample units of advanced drinking water treatment processes, namely, pre-ozonation, conventional water treatment (CWT), and main ozonation/biological activated carbon (BAC), were obtained from the drinking water treatment plant in South China. Biodegradable dissolved organic carbon (BDOC) and assimilable organic carbon (AOC), which is a component of BDOC, were measured as indicators of organic matter biodegradability and biological stability in drinking water. Results showed that the high-MW organic matter in raw water was oxidized into low-MW organic matter (MW < 3 kDalton) through preozonation process, thereby enhancing the BDOC content in raw water. BDOC components were removed by the subsequent CWT process. Components of the effluent organic matters obtained from the CWT process were completely decomposed through the main ozonation process, and the remaining organic matters were simultaneously oxidized into low-MW organic matters, thus increasing the BDOC content and improving the biodegradability. Finally, the low-MW BDOC was efficiently removed through BAC process. The AOC content in user water was over 100 mu g L-1, indicating that the factors contributing to biological instability remained. Additional attention should be given to BAC protection in China.