Ozonation of bromide-containing water can produce bromate exceeding the maximum contaminant level of 10 �g/L regulated by USEPA. The ammonia-chlorine process has been found as an effective bromate control strategy: by adding ammonia and then chlorine prior to ozonation. However, chemistry responsible for the effective control is unclear. We hypothesize that ammonia reacts with chlorine to form monochloramine, which further reacts with bromide to form bromochloramine to reduce the bromate formation. Bromochloramine decomposes with time, with a half-life of approximately 3 times longer than that of monobroamine. More importantly, less bromide is released. Although bromide could be generated from bromochloramine decomposition, the bromide reacts with remaining bromochloramine to form bromamines so that less bromide is available to form bromate. Also, bromochloramine and its decomposition products may serve as hydroxyl radical scavengers to minimize bromate formation from hydroxyl radical-driven pathways. Tests asserting the involving chemistry are ongoing and will be presented.

Does bromochloramine formation explain the good bromate control by the ammonia-chlorine process during ozonation?

243rd National Meeting (2012)

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