AWWA WQTC71659

The occurrence of N-nitrosodimethylamine (NDMA) and its precursors on ozonation and chloramination of water were investigated. A national survey of NDMA confirmed the frequent presence of NDMA in water sources of the Yodo and Tone River basins, the first and second largest basins on a population basis in Japan, at the level of several ng/L. Relatively high concentrations of NDMA were also shown to be formed by ozonation, especially in the Yodo River basin. In sewage treatment plants (STPs) located in the Yodo River basin, NDMA concentrations before and after ozonation were 16 - 290 ng/L and 14 - 440 ng/L, respectively. At one STP in the area, an extremely high concentration of NDMA formation (10000 ng/L) was found after ozonation in one influent water sample. NDMA precursors on ozonation in the influent at the STP were partly identified as anti-yellowing agents. In the middle Tone River basin, NDMA and its precursors were frequently detected on chloramination regardless of the season. In the upper Tone River basin, the STP effluents were shown to contribute to the sources of NDMA precursors in the downstream water. NDMA concentrations after chloramination of the STP effluents ranged from 140 to 240 ng/L. NDMA itself was shown to be contained at high levels (> 30000 ng/L) in industrial discharge from a livestock animal treatment facility. Includes 14 references, tables, figures.