A comprehensive survey on the occurrence and fate of nitrosamines in sewage treatment plants and water environment.

A comprehensive examination of nitrosamines was conducted in a water system, which included sewage treatment plants (STPs), river water, and seawater to understand their characteristic occurrence and fates in whole real water system. The concentrations of nitrosamines were highest in the STP influent (1440-29,100ng/L), followed by the river water (26.0-5180ng/L), the STP effluent (9.58-310ng/L), and seawater (44.2-155ng/L). The samples were especially affected by proximity to the industrial zone and the samples collected near industrial complex had much higher levels than others with different distribution patterns. In the STPs, nitrosamines were mostly eliminated during biological treatment processes (86.7-95.0%), while they were formed through chlorination processes (-59.6 to -27.7%), which is consistent with previous surveys. The primary clarifier showed insignificant elimination tendencies (5.6-28.2%). Although removal by ultraviolet light was effective (73.2-94.1%), more surveys may be needed because of conflicting results in other studies. Among water quality parameters, nitrosamines in waste water were linked with organic carbon and nitrogen levels.