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Some N-nitrosamines are probable human carcinogens and disinfection by-products. This study focused on a wastewater-affected drinking water supply in the Yangtze River Delta, China, that was highly dominated by low-molecular-weight organic matter, aromatic proteins, and soluble microbial products (SMPs) and low in humic substances. The study water presented a unique opportunity to investigate treatment processes for controlling an array of nitrosamines because it contained precursors for five N-nitrosamines [N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA), N-nitrosopiperidine, N-nitrosomorpholine, and N-nitrosopyrrolidine] whereas only NDMA precursors have been detected in most North American waters. Although conventional processes removed only low levels of precursors, advanced treatment processes effectively removed precursors as well as aromatic proteins and SMPs. Ozone destroyed and/or transformed precursors (e.g., median of 45% for NDMA and 22% for NDEA). Granular activated carbon proved more effective in removing precursors (e.g., median of 88% for NDMA and 83% for NDEA) than in removing bulk dissolved organic carbon (median ~ 60%). [ABSTRACT FROM AUTHOR]