Organic chloramines in chlorine-based disinfected watersystems: A critical review

This paper is a critical review of current knowledge of organic chloramines in water systems,including their formation, stability, toxicity, analyticalmethods for detection, and their impacton drinking water treatment and quality. The term organic chloramines may refer to anyhalogenated organic compounds measured as part of combined chlorine (the differencebetween themeasured free and total chlorine concentrations), andmay include N-chloramines,N-chloramino acids, N-chloraldimines and N-chloramides. Organic chloramines can formwhen dissolved organic nitrogen or dissolved organic carbon react with either free chlorineor inorganic chloramines. They are potentially harmful to humans and may exist as anintermediate for other disinfection by-products. However, little information is available on theformation or occurrence of organic chloramines in water due to a number of challenges. One ofthe biggest challenges for the identification and quantification of organic chloramines in watersystems is the lack of appropriate analytical methods. In addition, many of the organicchloramines that formduring disinfection are unstable,which results in difficulties in samplingand detection. To date research has focussed on the study of organic monochloramines.However, given that breakpoint chlorination is commonly undertaken in water treatmentsystems, the formation of organic dichloramines should also be considered. Organicchloramines can be formed frommany different precursors and pathways. Therefore, studyingthe occurrence of their precursors in water systems would enable better prediction andmanagement of their formation.