ABSTRACT
As mandated by the 1986 Safe Drinking Water Act amendments, the USEPA is currently developing regulations for disinfection by-products (DBPs). In addition to potentially lowering the existing THMs standard, the USEPA may regulate other DBPs. One ozone by-product under consideration is bromate. The surface water treatment rule (SWTR) has established disinfection requirements for utilities based on minimum CT values. Utilities must control pathogenic microorganisms while minimizing the formation of other harmful DBPs. Proposed drinking water regulations in the U.S. will specify a maximum contaminant level (MCL) of 10 μg/l for bromate ion (BrO3 −), an ozonation by-product produced during drinking water treatment. Several different options to remove BrO3 − after its formation, applicable to conventional surface water treatment plants contemplating the use of ozone at various points of application, have been evaluated: ferrous iron reduction (Fe2+), activated carbon surface reduction (GAC), and ultraviolet irradiation (UV). In all processes, chemical analysis of the treated water showed the formation of bromide ion (Br−) indicating that chemical reduction of BrO3 − is the significant mechanism; adsorption of BrO3 − onto the surface of iron floe is insignificant. BrO3 − removal is activated carbon specific, and not all carbons have shown the ability to reduce BrO3 − to Br−.
