Suspect screening of disinfection byproduct precursors in water treatment processes using ultrahigh resolution mass spectrometry

Abstract

Disinfection byproducts (DBPs) formed by reaction between dissolved organic matter (DOM) and chlorine remain a persistent challenge for producing high quality drinking water. The complex chemical mixture of DOM has hindered the development of targeted removal strategies for DBP precursors. Here, we used ultrahigh resolution mass spectrometry to investigate how the formation of DBPs from components of three different DOM isolates (terrestrial, wastewater effluent-derived, and algal-impacted) responded to conventional treatments of permanganate oxidation, alum coagulation, and activated carbon sorption. We report that the three isolates responded differently to permanganate oxidation, a conventional strategy to remove DBP precursors, in terms of both carbonaceous and nitrogenous DBP formation potential. In some cases, permanganate could directly oxidize DBP precursors or improve the removal of DBP precursors by subsequent alum coagulation; while in other cases, permanganate oxidation was not effective. Combinations of activated carbon sorption and alum coagulation were widely effective in reducing DBP formation from all isolates studied, but the removed precursors differed between isolates. Finally, possible persistent DBP precursors, not removed by any treatment, were identified with plausible chemical structures proposed based on the ionization techniques and ion types. Overall, the identification of DBP precursors can aid in the development of targeted removal strategies.