Formation of disinfection byproducts during chlorination of mixed nitrogenous compounds in swimming pools

Disinfection byproducts (DBPs) in swimming pool waters are receiving increasing attention because of their toxicity and widespread occurrence. Current studies rarely investigate the formation of DBPs from typical precursors in swimming pools under mixed exposure. They also rarely investigate the formation of carbonaceous DBPs (C-DBPs) and nitrogenous DBPs (N-DBPs) simultaneously. In this study, the formation of C-DBPs and N-DBPs were investigated during chlorination of mixed precursors (i.e., tryptophan, urea, creatinine, and ammonia). The effects of precursors and operation parameters were also investigated. Among the four precursors, tryptophan had the highest DBP formation potential. Urea and ammonia restrained the formation of C-DBPs but promoted the formation of more toxic N-DBPs. C-DBP yields were significantly higher than N-DBP yields under all experimental conditions. Longer reaction time and higher chlorine dosage promoted the formation of C-DBPs, while higher temperature decreased the concentration of N-DBPs. The presence of bromide not only improved the sum yields of DBPs, but also shifted chlorinated DBPs to brominated species. (C) 2020 Elsevier B.V. All rights reserved.