The control of emerging haloacetamide DBP precursors with UV/persulfate treatment

Haloacetamides (HAcAms), an emerging class of nitrogen-containing disinfection byproducts (N-DBPs) of health concern in drinking water, have been reported to occur in treated drinking waters at low μg/L levels typically. The objective of this study was to examine the potential of an ultraviolet light/persulfate (UV/PS) oxidation technology to reduce the precursors of HAcAms and also minimize the formation of other N-DBPs upon subsequent chlorination. Low-pressure UV photolysis alone and PS pre-oxidation alone did not significantly affect HAcAm formation, however UV/PS pre-oxidation achieved a statistically significant reduction in HAcAm formation and also reduced bromine incorporation into the HAcAms. UV/PS also showed a good performance in removing the precursors of haloacetonitriles and halonitromethanes prior to chlorination. Therefore, UV/PS has the potential to minimize the formation of a range of N-DBPs in organic nitrogen-rich waters where N-DBP precursors are prevalent. However, these benefits should be weighed against the potential drawbacks of increased bromate and sulfate formation, particularly in high-bromide waters. [Display omitted] •UV photolysis or persulfate (PS) oxidation alone cannot change HAcAm formation.•79–91% HAcAm precursor removal with UV/PS treatment in the studied waters.•UV/PS reduced bromine incorporation in HAcAms but resulted in bromate formation.•UV/PS has the potential to minimize a range of N-DBP formation during chlorination.•UV/PS reduced N-DBP formation more than it destroyed DON.