Chloramine was often used as chlorine alternative for trihalomethanes (THMs) and haloacetic acids (HAAs) control. However, nitrogenous disinfection byproducts (N-DBP) formation and nitrification in distribution were always major concerns in chloramination practices. For Kinmen Island, the high organic nitrogen in raw water may increase the nitrogenous DBP formation. Simulated distribution system tests were conducted to explore the DBP formation kinetics in the distribution system. Lower haloacetonitrile (HAN4) formation (0.26 μgL−1) formation from chloramination than with chlorination (10.48 μgL−1) was observed from the 24 hours reaction time. The nitrogen source contributed to the dichloroacetonitrile (DCAN) formation kinetics were explored with 15N-chloramination. The results showed that nitrogen source from organic nitrogen was more dominate in DCAN formation with low chloramine dosage. It suggested that chloramine contributed to less DCAN formation in practice, especially for short distribution systems. The problem of THMs exits in process effluent as result of pre-chlorination affect the THM4 concentration in disinfection effluent. In summary, the results provide evidence that simultaneous post-chloramination and pre-chlorination would become feasible disinfection strategy applied to control regulated THMs and HAAs formation in Kinmen Island.
- disinfection byproduct
- haloacetic acid
- simulated distribution system test
- First received 20 February 2015.
- Accepted in revised form 1 June 2015.
- © IWA Publishing 2015