Chlorine transfer from inorganic monochloramine in chlorinated wastewater

The primary disinfectant in wastewater treatment is inorganic monochloramine, formed from the reaction of added chlorine with ammonia. Laboratory studies have shown that monochloramine can transfer chlorine to nitrogenous organics, producing organic chloramines that are weak disinfectants. Thus, chlorine transfer from monochloramine may result in poorer disinfection. In this study, chlorine transfer them monochloramine was observed in 4 of 10 samples collected from four wastewater treatment facilities. Chlorine acceptors in these wastewaters reacted with monochloramine about as fast as amino acids and peptides reacted with monochloramine. The monochloramine concentration was reduced by one-half in approximately 10 to 70 minutes. Evidence was found for negative interferences in the measurement of total residual chlorine (TRC) by amperometric titration. A rapid spectrophotometric method was developed to measure TRC more precisely.