The Removal of N-Nitrosodimethylamine Formation Potential in Drinking Water Treatment Plants

Nitrogenous disinfection by-products (N-DBPs) are far more cytotoxic and genotoxic than carbonaceous DBPs (Plewa & Wagner 2009). Among the N-DBPs, nitrosamines have been shown to be probable human carcinogens associated with 10–6 lifetime cancer risk at ng/L levels (USEPA 2002). An increasing number of water treatment plants (WTPs) in the United States have been using or considering chloramination over chlorination to comply with the stringent regulations for halogenated DBPs such as trihalomethanes (THMs) and haloacetic acids (Li 2011). However, nitrosamines have been detected at notable levels in chloraminated waters (Russell et al. 2012, Nawrocki & Andrzejewski 2011, Charrois & Hrudey 2007, Mitch et al. 2003, Choi & Valentine 2002). N-nitrosodimethylamine (NDMA) has been the most commonly detected nitrosamine species in US drinking water distribution systems (Woods & Dickenson 2015, Russell et al. 2012, Bond et al. 2011, Wang et al. 2011). There are currently no federal regulations for nitrosamines in drinking water systems. However, five of them were included in the US Environmental Protection Agency’s (USEPA’s) third Contaminant Candidate List (USEPA 2009), and USEPA is expected to make a regulatory determination for the nitrosamines during the Six-Year Review of the Disinfectants and Disinfection Byproducts Rules (D/DBPRs).