Occurrence and formation of haloacetamides from chlorination at water purification plants across Japan

Abstract The occurrence of six haloacetamides (HAcAms), which are a group of emerging nitrogenous disinfection byproducts, was investigated in drinking water across Japan in September 2015 and February 2016. At least one of the six HAcAms were found in all of the drinking water samples and their total concentrations ranged from 0.3 to 3.8 μg/L. The detection frequencies and concentrations of 2,2-dichloroacetamide (DCAcAm) and 2-bromo-2-chloroacetamide (BCAcAm) were the largest among the targeted HAcAm species. The total HAcAm concentrations in the raw water after chlorination ranged from 0.8 to 11 μg/L. The bromine incorporation factors (BIFs) of the targeted dihalogenated HAcAms (di-HAcAms) (DCAcAm, BCAcAm, and 2,2-dibromoacetamide) in the drinking water samples correlated well with those in the raw water after chlorination. The total HAcAm concentrations and the BIF of the di-HAcAms in the raw water after chlorination correlated with trihalomethane concentrations. HAcAm concentrations after chlorination increased with chlorination time. While the formation of di-HAcAms after chlorination was higher at higher pH, that of 2,2,2-trichloroacetamide remained unaffected by pH.