N-nitrosamines are a group of highly carcinogenic emerging disinfection byproducts (DBPs) formed during disinfection, especially when utilizing monochloramine (MCA) as the secondary disinfectant in the distribution systems. This study was targeted to evaluate N-nitrosamines formation at each step of water treatment processes and control/minimize N-nitrosamines formation by removing/controlling their precursors. The water samples were collected from different drinking water facilities across the mid-west region of United States including ground and surface water resources. Seven major N-nitrosamine precursors and eight major N-nitrosamines were monitored quarterly for each water system throughout the entire treatment processes. A newly developed sensitive ultra-fast liquid chromatography-tandem mass spectrometry method was used for the analysis of precursors, and a highly accurate and precise isotope dilution gas chromatography-mass spectrometry method was used for the detection of N-nitrosamines. The removal of N-nitrosamine precursors using different adsorbents was studied. Results indicated that the N-nitrosamines and precursors were not detectable or very low in majority of the studied water systems. N-nitrosamine formation potentials (FPs) were very low for the finished drinking waters as well. However, when precursors were present (i.e., spiked in), high FPs were resulted from MCA disinfection, followed by free chlorine, and Minimum from peracetic acid. Natural zeolites removed over 90% of studied N-nitrosamines precursors.

Occurrence and control of N-nitrosamines and their precursors in drinking water system

248th National Meeting (2014)

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