RESUMEN
Cyclops of zooplankton propagates prolifically in eutrophic waterbody and it cannot be exterminated by conventional disinfection process. The mutagenicity of Mesocyclops leukarti and its extermination with oxidants in a drinking waterworks in China were studied. Among five oxidants for use in bench-scale, chlorine dioxide is the most effective and the potassium permanganate is the weakest against Mesocyclops leukarti under the same conditions. Full-scale results showed that Mesocyclops leukarti could be effectively removed from water by 1.0 mg/L chlorine dioxide preoxidation combined with conventional removal physical process. After filtration, chlorite, a by-product of prechlorine dioxide, is stable at 0.45 mg/L, which is lower than the critical value of the USEPA. GC-MS examination and Ames test further showed that the quantity of organic substance and the mutagenicity in water treated by chlorine dioxide preoxidation are obviously less than those of prechlorination.