AWWA WQTC69420

Chlorination in drinking water systems has been instrumental in decreasing waterborne diseases. However, free chlorine can interact with organics in the water to form regulated disinfection byproducts (DBPs). Therefore, many water utilities are switching to chloramines to reduce the levels of DBPs. Chloraminated systems can suffer from nitrification when free ammonia is converted to nitrite and then nitrate. Nitrification episodes in chloraminated drinking water distribution systems are thought to be caused by autotrophic nitrifiers. An observation has been that there is an increase in heterotrophic bacterial abundance during nitrification, and the study hypothesis is that heterotrophs may also be contributing to nitrification since it is known that these bacteria are capable of nitrification in many environments. In a reactor that simulates premise plumbing, nitrification was found to be affected minimally by chlorite treatment, suggesting a possible contribution to the nitrification process by organisms other than autotrophic bacteria. A heterotrophic nitrifying bacteria was isolated from the effluent of this reactor. The isolation of organisms such as the one in this study can provide a positive control for the design of a molecular method to track heterotrophic nitrification and thus possibly predict nitrification events in the DWDS. Likely gene targets for tracking heterotrophic nitrification include the heterotrophic ammonia monooxygenase (AMO) gene and the heterotrophic hydroxylamine oxidoreductase (HAO). Includes 25 references.