Characterization and comparison of disinfection by-products of four major disinfectants

Disinfection by-products (DBFs) generated from chlorination, chloramination, ozonation, and chlorine dioxide treatment were characterized and compared. DBPs examined included four trihalomethanes, nine haloacetic acids, four haloacetonitriles, two haloketones, chloropicrin, total organic halogen (TOX), total organic bromine (TOBr), total organic chlorine (TOCl), thirteen aldehydes, and bromate. The contributions of known DBFs to TOX, TOCl and TOBr formed from using different disinfectants were given. The reaction of humic substances with small amount of free chlorine in equilibrium with NH2Cl constitutes an important pathway for the formation of TOCl during chloramination. The yields of TOBr and total aldehydes produced from using each disinfectant were found to be related to the redox potential corresponding to each disinfectant. This work makes a step toward better decisions about which disinfectant poses the lowest risk to human health.