MIEX® and PAC for removal of hydrophilic DBP precursors

Abstract

The objective of this research was to investigate promising materials for potential reduction of disinfection by‐product (DBP) formation resulting from reactions with hydrophilic natural organic matter (NOM), a source of precursors that is difficult to remove with conventional drinking water treatment process units. DBP reduction in other reported research was attributable to greater removal of hydrophobic fractions of NOM. Two nonionic resins were used to fractionate NOM before and after treatment with magnetic ion exchange (MIEX®) and a powdered activated carbon. At the chosen doses of treatment materials, bulk NOM removal remained the same (< 10% difference in dissolved organic carbon after treatment with activated carbon versus MIEX); compared with the powdered activated carbon, however, MIEX provided greater reduction of trihalomethane and haloacetic acid formation potential resulting from reactions with hydrophilic NOM. Therefore, MIEX preferentially removed hydrophilic DBP precursors. Similar results were observed for the transphilic fraction, whereas differences in the hydrophobic fraction were minimal. This research has implications for treatment facilities with elevated levels of highly reactive hydrophilic NOM in their influents and highlights the importance of source water chemistry in the selection of DBP mitigation strategies.