Control of Nitrosamines, THMs, and HAAs in Heavily Impacted Water with O 3 ‐BAC

Comprehensive control of regulated trihalomethanes (THMs) and haloacetic acids (HAAs), as well as nitrosamines, is needed to address forthcoming regulations. The formation potentials (FPs) of these disinfection by‐products (DBPs) with chlorination (Cl 2 ) and chloramination (NH 2 Cl) were investigated along the treatment train of a conventional and ozone‐biologically active carbon (O 3 ‐BAC) process. The nitrosamines FP‐NH 2 Cl, THM FP‐Cl 2 , and HAA FP‐Cl 2 in heavily impacted source water in China were as high as 333 ng/L, 307 µg/L, and 247 µg/L, respectively, indicating that there was a high risk of DBP formation in the finished water. A combination of conventional and O 3 ‐BAC processes reduced nitrosamine FP‐NH 2 Cl to 39 ng/L, achieving an 88% removal. This process also reduced THM FP‐Cl 2 and HAA FP‐Cl 2 to 197 and 174 µg/L, with fairly low removals of 36 and 29.5%, respectively. The strategy for this water was to apply conventional and O 3 ‐BAC processes to substantially eliminate nitrosamine precursors and then apply chloramination to control THMs and HAAs.