LAUSR

Abstract Because it promotes efficient gas solubility, microbubble aeration has been widely used in ozonation of water systems. In conventional ozone treatment, disinfection by-products (DBPs) are a significant concern during subsequent chlorination, especially when raw water contains bromide. However, the effect of microbubbles ozonation on the formation of DBPs is not well characterized. In this study, we investigated the formation of DBPs during chlorination of bromide-containing water from Tai Lake after microbubble ozonation, and compared this to conventional bubbling. The results suggest that more bromate and bromo-organic DBP precursors were produced after microbubble ozonation, which creates a challenge to the practical implementation of microbubble ozonation in water treatment. Since bromate is the main DBP of concern in the presence of bromide during ozonation, we also explored the effect of natural organic matter and hydroxyl radicals on bromate formation. Finally, we found that the addition of ammonia reduced bromate formation during microbubble ozonation to levels even lower than with conventional bubble ozonation.