Seminar

N-Nitrosodimethylamine Formation and Control at Drinking Water Treatment Plants

Abstract

An increasing number of drinking water utilities in the United States have been employing or considering chloramination for disinfection to comply with the stringent regulations for trihalomethanes (THMs) and haloacetic acids (HAAs). However, nitrosamines, a class of emerging disinfection by-products (DBPs), may occur in chloraminated waters. Nitrosamines are classified as probable human carcinogens in water at very low concentrations; for instance, with a 10–6 lifetime cancer risk for 0.7 ng/L of N-nitrosodimethylamine (NDMA) in drinking water. NDMA is the most commonly detected and reported nitrosamine in distribution systems in the US. As a result, there has been an increased regulatory attention by the US Environmental Protection Agency that included nitrosamines in the Contaminant Candidate List 3. The goal of this presentation is to present results from an on-going research project entitled “The Seasonal Patterns of NDMA Formation Potentials in Water Sources and at Drinking Water Treatment Plants.” The specific objectives are to examine the impacts of seasonal variations and climatic events on the occurrence of N- NDMA precursors in selected surface waters, and to assess the removal efficiency of the NDMA precursors at the different full-scale treatment processes, which are currently optimized for USEPA’s Stage 2 D/DBPR.