Abstract
Ozone oxidize bromide ions (Br-) to form bromate ions (BrO3-). With coexisting organic compounds which have 260nm ultraviolet absorbance, ozone oxidize organic compounds and yield aldehydes as organic ozonation by-products prior to forming bromate ions. In laboratory-scale ozonation experiments of natural river water, bromate formation was inhibited by coexisting organic matters in original water, while total organic halides (TOX) and aldehydes were increased. Phosphate also worked as a scavenger to inhibit bromate formation in ozonation. In the constant initial pH conditions, bromate concentration was gradually increased in accordance with low ozone dose per TOC (O3/TOC), but severely increased at a certain high O3/ TOC. When pH was as high as 8, bromate formation was accelerated even at lower O3/TOC. Bromate formation should be prevented by the optimized minimum ozone dose just enough to oxidize target substances.
