Temperature dependence of characteristics of organic precursors, bromide, and disinfection byproduct formation.

ABSTRACT

This study characterized the potential effects of elevated water temperature on source water quality and corresponding disinfection byproduct (DBP) formation. Results of laboratory simulations showed that although DBP formation increased with temperature, both the concentrations of dissolved organic carbon (DOC) and DBP formation decreased when water was incubated at higher temperatures (35 °C) prior to chlorination, probably due to increased microbial activity leading to greater degradation of organic precursors that affects DBP formation. However, the effect of incubation temperature prior to chlorination on final DBP formation varies with the characteristics of source water. When bromide was present, the ratio of Br-DBPs increased. The concentrations of total trihalomethanes (THMs) and haloacetonitriles (HANs) also increased when levels of bromide increased. This trend was not substantial for total haloacetic acids (HAAs). The hydrophobic organic precursors of THMs and HANs can be effectively removed by coagulation and filtration processes, and the effects of higher incubation temperature may thus be compromised. However, no apparent changes were observed for HAAs. The effects of bromide may also be more apparent in HAA and HAN formation after coagulation and filtration treatments.