Evaluation of DBPs in Sequential Disinfection ofOzone and Chlorine Dioxide for CryptosporidiumInactivation

摘要

The DBPs formed by the sequential disinfection of ozone and chlorinerndioxide have been investigated by laboratory-scale experiments usingrnLake Biwa water under the conditions of 2-log inactivation ofrnCryptosporidium in one hour. The measurements of DBPs after a lapsernof 24 hrs from disinfectant addition revealed that the concentrations ofrnresidual chlorine dioxide, chlorite and bromate could be controlled wellrnby the sequential disinfection below their Japanese Drinking WaterrnGuideline values or MCL values of USEPA. However, these DBPs byrnconventional ozone disinfection and chlorine dioxide disinfection werernmuch higher than their guideline values. This fact was considered to bernattributed not only to low disinfectants doses in the sequentialrndisinfection, but also to the reduction in amount of chlorine dioxidernconsumed at ozone and GAC treatment prior to the addition of chlorinerndioxide. Thus it was concluded that the sequential disinfection could berna promising disinfection method because this disinfection method could