Chloraminesare formed as a result of the reaction between ammonia and dissolved chlorine(usually hypochlorous acid or HClO). The disinfectant potential of chloramineswas already identified in the early 1900s and they were initially usedprimarily to remove foul tastes and odors from drinking water.
However,chloramines were later to be observed as more stable compared to free chlorinewhich readily dissipates, making them ideal for preventing the regrowth of bacteria. Because of this stability, chloramines are now being utilized for continued protection as water moves through the pipes and distribution network.
The reactionof ammonia with aqueous chlorine produces organic chloramines and three types of inorganic chloramines: monochloramines, dichloramines, and trichloramines.Monochloramines are the kind most commonly produced and utilized for watertreatment, although higher concentrations of ammonia can form more di- and tri-chloramines.
There are some advantages to using chloramine as a disinfectant, particularly in secondary water disinfection. For one, chloramines remain in water for are relatively longer period of time and continue to kill pathogens even when free chlorine has dissipated already. In addition, chloramines produce fewer disinfection byproducts (DBPs). Chloramines also leave water with a better taste and smell and do not change the pH of water.