The Genotoxicity of the Organics in Effluent From Different Treating Processes of 6 Water Works in Shenzhen

PP-31-192 Background/Aims: To detect and assess the genotoxicity of the organic extracts in effluent of 6 water works in Shenzhen. Methods: The Salmonella mutagenicity test was used to detect the mutagenicity of water samples collected from 6 water works (A, B, C, D, E, and F) on May and June, 2008, Shenzhen. Results: Except for the water sample from active carbon pool of B water works, all other showed positive result for Ames test, and the type of mutagenicity was mainly code-shifting. The intensities of mutagenicity of every water samples during the treatment were as follows: A: output water > precipitated-filtrated water > source water > second chlorinated water > tap water > prechlorinated water; B: source water > second chlorinated water > precipitated-filtrated water > tap water > output water > active carbon filtrated water; C: prechlorinated water > output water > precipitated-filtrated water > source water > tap water > second chlorinated water; D: tap water > precipitated, filtrated water > prechlorinated water > output water > source water; E: output water > prechlorinated water > tap water > precipitated-filtrated water > second chlorinated water > source water; F: second chlorinated water > precipitated-filtrated water > source water > output water > tap water. The comparisons of mutagenicity of output water among 6 water works: TA98 (−S9): E > D > C > A > F > B; TA98(+S9):E > C > F > D (A, B were negative); TA100 (−S9): E > F > C > A (D, B were negative); TA100 (+S9): only E was positive. Conclusion: The mutagenicity of Dongjiang river decreased after the treatment of B and F water works, increased after the treatment of A and C; the mutagenicity of Dongjiang river plus reservoir water source increased after the treatment of D and E. The treatment techniques of pre-O3-O3-bioactive carbon filtration had positive effect in reducing the mutagenicity of output water. During the treatment techniques, cancelling of the prechlorination or using the dioxochloride replaced for chlorine as the disinfectant might have positive effect toward optimizing the quality of output water.