Nitrogen enriched dissolved organic matter (DOM) isolates and their affinity to form emerging disinfection by-products

Abstract

Increased contributions from wastewater discharges and algal activity in drinking water supplies can lead to elevated levels of dissolved organic nitrogen (DON), which can increase the likelihood for the formation of emerging nitrogenous disinfection by-products (N-DBPs) of health concern. Dissolved organic matter (DOM) isolated from five waters, using a newly developed DOM isolation method specific to DON fractionation, produced thirty-four isolates of suitable mass. Each isolate was treated with free chlorine or chloramines under formation potential conditions. The DBP yields were determined for three halogenated DBPs (trichloromethane, dichloroacetonitrile, and trichloronitromethane) and one non-halogenated DBP (N-nitrosodimethylamine [NDMA]). Halogenated DBP yields were greater during the application of free chlorine, however chloramination produced significant levels of halogenated N-DBPs for some isolates. NDMA was only observed to form from selected nitrogen-enriched isolates (DOC/DON ratio < 20 mg/mg), especially those isolated from treated wastewater. Other results indicated that nitrogen-enriched DOM resulted in increased yields of the other N-DBPs studied.