Effect of ferric and bromide ions on the formation and speciation ofdisinfection byproducts during chlorination

The e ects of ferric ion, pH, and bromide on the formation and distribution of disinfection byproducts (DBPs) during chlorinationwere studied. Two raw water samples from Huangpu River and Yangtze River, two typical drinking water sources of Shanghai, wereused for the investigation. Compared with the samples from Huangpu River, the raw water samples from Yangtze River had lowercontent of total organic carbon (TOC) and ferric ions, but higher bromide concentrations. Under controlled chlorination conditions,four trihalomethanes (THMs), nine haloacetic acids (HAAs), total organic halogen (TOX) and its halogen species fractions, includingtotal organic chlorine (TOCl) and total organic bromide (TOBr), were determined. The results showed that co-existent ferric andbromide ions significantly promoted the formation of total THMs and HAAs for both raw water samples. Higher concentration ofbromide ions significantly changed the speciation of the formed THMs and HAAs. There was an obvious shift to brominated species,which might result in a more adverse influence on the safety of drinking water. The results also indicated that high levels of bromideions in raw water samples produced higher percentages of unknown TOBr.