Chloramine (Mono) For Water And Wastewater

Chloramination disinfection is the practice of forming inorganic chloramines in water to reduce microbial concentrations to within acceptable limits. The chloramines -- monochloramine (NH2Cl), dichloramine (NHCl2) and nitrogen trichloride (NCl3) -- form when chlorine and ammonia are combined in water. Traditionally, treated wastewater, which contains ammonia, is disinfected by the addition of chlorine. In recent years, many drinking water facilities have converted to chloramination to disinfect potable water. Roughly 20% of all drinking water facilities in the United States now use chloramines as the residual disinfectant.

For the chloramination of drinking water, monochloramine is the preferred disinfectant. Formation of dichloramine and nitrogen trichloride is avoided, since more chlorine is consumed and the presence of these chloramines can produce odors or off-tastes.

In treated wastewater, any organic nitrogen compounds present will form organic chloramines during chlorination. Organic chloramines, as a class, are much weaker disinfectants than the inorganic chloramines. Chlorine overfeeds and ineffective mixing can lead to greater production of organic chloramines, thereby diminishing the total germicidal activity.