Identification of new drinking water disinfection by-products formed in the presence of bromide

Using a combination of mass spectrometry and infrared spectroscopy, disinfection by-products (DBPs) were identified in ozonated drinking water containing elevated bromide levels, and in ozonated water treated with secondary chlorine or chloramine. Only one brominated by-product-dibromoacetonitrile - was found in the water treated with only ozone. Many more by-products were identified when secondary chlorine or chloramine was applied after ozonation. A number of these by-products have not been reported previously. When comparing low-bromide water to water with elevated bromide, a tremendous shift in speciation was observed for samples treated with secondary chlorine or chloramine. Without high bromide levels, chlorinated species dominate (e.g., chloroform, trichloroacetaldehyde, tetrachloro-propanone, dichloroacetonitrile, trichloronitromethane); with elevated bromide levels (1 mg/L), these shift to brominated species (e.g., bromoform, tribromoacetaldehyde, tetrabromopropanone, dibromo-acetonitrile, tribromonitromethane). An entire family of bromo- and mixed chlorobromopropanones was identified that were not present in library databases, and have not been reported previously. They were observed mainly in the ozone-chloramine samples, but were also present in ozone-chlorine-treated water. These brominated by-products were also observed in water treated with only chloramine or chlorine.