Effect of blending ratio on the formation of bromoform and bromate in blended water samples disinfected with chlorine or ozone

This study was carried out to assess the potential formation of bromoform and bromate in drinking water samples prepared by blending desalinated and brackish ground water when disinfected by chlorination or ozonation methods. The levels of bromoform and bromate were determined under various treatment conditions including blending ratios, disinfectant dosage, temperature, and reaction time. Results showed that bromoform increases as chlorine dosages increases from 1 to 5 ppm. The blending ratio of 1:10 (v/v, brackish water: desalinated water) showed the lowest bromoform formation due to the low bromide ion content. Bromoform formation also increases with increasing reaction time and temperature. Results of the ozonation experiments indicated that high levels of bromate were detected only in blended water samples that were dosed with high levels of ozone (i.e., 2–5 ppm) regardless of the water blending ratio. Similar to bromoform, bromate formation increases with increasing the temperature and reaction time.