Formation and control of emerging C- and N-DBPs in drinking water

A survey of 16 US drinking water treatment plants was conducted on the occurrence, formation, and control of emerging disinfection by-products (DBPs). The formation and control trends of certain emerging carbonaceous (haloacetaldehyde) and nitrogenous (haloacetonitrile, halonitromethane, cyanogen halide, nitrosamine) DBPs were different from those of the regulated trihalomethanes (THMs). This was presumably due to differences in the sources of precursors (e.g., humic substances versus proteinaceous materials) plus differences in the impact of disinfection processes on these DBPs. For example, ozone increased the formation potential (FP) of chloropicrin, whereas biofiltration typically decreased the FP of the ozonated water. Alternatively, coagulation with the polymer polydiallyldimethylammonium chloride (polyDADMAC; a source of N-nitrosodimethylamine [NDMA] precursors) increased the FP of NDMA, whereas ozonation often destroyed NDMAFP. This article discusses how utilities can minimize and balance the formation of THMs and haloacetic acids with that of certain emerging DBPs. Expanded Summary