AWWA ACE54409

Ammonia has been shown to minimize bromate concentrations by blocking two of three potential bromate formation pathways. It was theorized that (bi)carbonate alkalinity in the presence of ammonia would further inhibit bromate formation since the pathway that ammonia does not block requires OH, and (bi)carbonate alkalinity is an OH scavenger. Experiments where (bi)carbonate alkalinity was increased from 50 mg/L to 119 mg/L (as CaCO3) in the presence of excess ammonia resulted in up to a 50% reduction in bromate formation, providing evidence in support of the theory. While OH is scavenged by (bi)carbonate alkalinity, it is promoted by H2O2. H2O2 that is formed when ozone reacts with natural organic matter may therefore render ammonia less effective. Experiments conducted in this study demonstrated this principle. Includes 19 references, figures.