AWWA ACE65605

A proven technology for minimizing the formation of bromate is ozonation of the waterat a reduced (typically acidic) pH. However, most waters that are high in bromide arerelatively high in alkalinity. In such waters, the cost of acid to lower the pH and caustic to raisethe pH back up for distribution can be higher than the cost of generating the ozone. Inaddition, there is an NSF limit on acid addition (i.e., 50 mg/L).In order to reliably comply with the bromate MCL of 10 g/L, many utilities aredesigning processes to meet the MCL with a 20-percent safety factor (i.e., 8 g/L). Becausethe 10-4 cancer risk level for bromate is at 5 g/L, some utilities are attempting to meet a lowerbromate goal. This paper discusses full-scale experiences at two ozone plants to comply with thebromate MCL or a lower health-based risk level, as well as the cost and feasibility. Includes 8 references, figures.



Keywords: Bromate; pH; Risks; Alkalinity; Ozonation; Cost Benefit Analyses