AWWA JAW56402

Bromate ion (BrO3 -) is a disinfection byproduct that is produced when raw water containing bromide ion (Br-) is ozonated. BrO3- is a concern for water utilities because it has been classified as a class II carcinogen, and the US Environmental Protection Agency has established a maximum contaminant level (MCL) of 10 ug/L for it in finished water. This study evaluated sulfite ion (SO3 2-) and reduced iron (Fe2+) as potential removal agents for BrO3- over a wide pH range. The experimental rate law for BrO3- removal using SO3 2- shows that the rate of removal decreases with increasing pH. The experimental rate law for BrO3- removal using Fe2+ shows that the rate of removal increases with increasing pH. The study found that under drinking water conditions, SO3 2- is not an effective BrO3- removal agent. However, at drinking water pH (pH > 7), Fe2+ is a good BrO3- reducing agent. The expanded rate law for BrO3- removal using Fe2+ predicts that at pH 8, 100 ug/L BrO3- is removed in 2 min. The study also found that the use of pickling Fe as the source of Fe2+ has the advantage of providing additional ferric ion for flocculation. (Fe2+ is produced during the pickling of steel, when concentrated hydrochloric acid is used to clean the surface of a sheet of steel.) Most current strategies regarding BrO3- address the prevention of its formation. This study shows that the capability to remove BrO3- permits water utilities that have high Br- concentrations in their source water to use stronger oxidants in high concentrations without exceeding the BrO3- MCL of 10 ug/L. The chemical removal process using Fe2+ also has the advantages of not being as complicated or expensive as current alternative technologies. Includes 30 references, tables, figures.