Development of a Bench-Scale Test to Predict the Formation of Nitrosamines: Executive Summary

The predominant nitrosamine observed in drinking water is N-nitrosodimethylamine (NDMA). NDMA may be formed via a nitrosation mechanism when sufficient nitrite is present and chlorine is primarily in the form of hypochlorous acid (HOCl). However, NDMA is typically not formed in the presence of free chlorine. NDMA may also be formed via a non-nitrosation mechanism in the presence of chloramines. Moreover, research has shown that dichloramine is more reactive in forming NDMA than monochloramine. The order of addition of chlorine and ammonia can impact NDMA formation, where the addition of chlorine to ammonia-containing water can result in a localized region with dichloramine and, thus, more NDMA formation. In other research on reclaimed wastewater, NDMA formation peaked at the breakpoint.