Evaluation of Bromide removal with Seasonal Level in the Processes of Advanced Water Treatment System

As the bromide (Br^-) containing water is used in drinking water treatment, the most major concern is the formation of brominated disinfection by-products (Br-DBPs). Among them, bromate (BrO₃^-) has been well proved to be more carcinogenic and mutagenic than other analogues. In this study, batch and continuous experiments were conducted to investigate the factors that influence the seasonal distribution and formation of bromate and bromide in the Nakdong River, which is used as a drinking water source. In addition, the behaviors of bromate and bromide as ozonation by-products (OBPs) in the processes of drinking water treatment systems were investigated. The mean influent concentrations were 3.1±0.7 mg/L for dissolved organic carbon (DOC) and 58.6±31.5 ug/L for bromide. As a result, bromide levels in the Nakdong River increased with decreasing water flow rate and decreasing water temperature. In pre- and post-ozonation, the concentration of OBPs increased with increasing bromide level, ozone dosage, and pH value. In particular, the concentration of OBPs forming in both pre-ozonation and winter was relatively higher than in both post-ozonation and summer. In terms of coagulation and sedimentation, polyaluminum sulfate organic magnesium (PASOM) coagulation resulted in slightly less OBP removal than polyaluminum silicate chloride (PASCl) coagulation. Moreover, bromate was effectively reduced in a three-month-old biological activated carbon filter.