Effect of bromide on NDMA formation during chloramination of model precursor compounds and natural waters

Abstract

In this work, we investigated the effect of bromide ion (Br−) on NDMA formation using model precursor compounds, wastewater effluents and surface waters. Previous studies showed that Br− reacts with chloramines and forms bromochloramine, a reactive compound responsible for NDMA formation enhancement. Some limitations of those studies were the highest Br− concentrations used, and the limited number of precursors considered. Here, we observed enhancement of NDMA formation from most of the model precursor compounds within the Br− range (0–1000 μg/L) but this effect was suppressed in the presence of NOM. Also, NDMA formation was favored at pH 8 in the presence of Br− compared to pH 6. Nevertheless, Br− suppressed NDMA formation in wastewater effluent samples at low monochloramine doses while no effects were observed in surface waters.