Availability and Minimization of Nitrogenous Disinfectant By-Products in Drinking Water

In view of high genotoxicity and cytotoxicity, the existence of nitrogenous disinfection by-products (N-DBPs) like haloacetonitriles, haloacetamides, nitrosamines, halonitromethanes, and nitrosamines is of higher concern as compared to regulated disinfectant by-products (DBPs). Due to exposure of DBPs the risk of bladder cancer is reported to be increased. The application of chlorine and other disinfectants, around 600 DBPs in drinking water was reported. Type of disinfectant is a main factor in formation of nitrogenous disinfectant by-products, nitrogen can be derived from chloramination, from the disinfectants or organic precursors such as organic nitrogen in dissolved state. The existing analytical methodologies detect three major groups of N-DPB Haloacetonitriles, Haloacetamides, and Halonitromethanes. Among these, Haloacetonitriles are available in higher concentration. Particularly, the hydrophobic acid formation is reported as the main source of trihalomethane precursors and may be removed by coagulation. Coagulation is useful for removal of colloids, but it cannot be applied to neutral fractions and similar reactive hydrophilic base. Filtration is also found to be ineffective for water treatment. Therefore, single method cannot be used to control all nitrogenous disinfectants by-products. This chapter describes the strategies to control disinfectant by-product formation based on water-specific assessment of precursor sources. The application of membranes and biodegradation to reduce DBPs is also discussed.