Effect of Separation Processes on the Formation of Brominated THMs

Separation treatment processes are being investigated as a way to control the formation of disinfection by‐products (DBPs) in finished waters. These processes remove natural organic matter before a disinfectant is applied, thus limiting the amount of material available to form DBPs. Four separation processes were examined in this study—granular activated carbon adsorption, powdered activated carbon adsorption, anion exchange, and membrane filtration—using two waters. Results showed that (1) as the dissolved organic carbon (DOC) decreased, the chlorination of diluted organic matter solutions held at constant bromide concentrations yielded a shift to brominated trihalomethanes (THMs); (2) at low DOC concentrations, the percentage of formed brominated trihalomethanes was higher in treated effluent than in influent water; and (3) the processes were most effective for controlling the formation of chloroform and least effective for controlling the formation of bromoform. Based on these results, it can be concluded that effective control of brominated THMs by these separation processes may be difficult for waters containing significant concentrations of bromide.