Formation of carbonaceous and nitrogenous disinfection by-products during monochloramination of oxytetracycline including N-Nitrosodimethylamine

Formation of typical volatile carbonaceous and nitrogenous disinfection by-products (C-DBPs and N-DBPs) during aqueous monochloramination of oxytetracycline (OTC) was investigated in this study. Impact factors including reaction time, pH, monochloramine (NH2Cl) dosages, and bromide concentrations were examined. The results showed that six DBPs including chloroform, dichloroacetonitrile, trichloronitromethane, 1,1-dichloropropanone, 1,1,1-trichloropropanone, especially extreme toxic N-Nitrosodimethylamine were found. Formation of these DBPs increased over time and monochloramine dosages with maximum yields given as 14.2, 4.3, 0.8, 2.1, 0.7, and 4.1 mu g/mg at pH 7, respectively (mu g/mg represents DBPs yields per mg of OTC). Solution pH exerted significant influence on the formation of all the DBPs species. Peak yields were found under circumneutral conditions. Production of bromine-substituted DBPs increased in the presence of bromide. Removal of presented OTC in waters should be implemented before chloramination disinfection process in drinking water treatment.