Determination Of Trace Bromate In Water And The Pilot Study Of Catalytic Ozonation In Reducing The Yield Of Bromate

Bromate can be formed during ozonation of raw waters containing bromide ions. The bromate has been classified as a class II-B carcinogen by the World Health Organization (WHO). The WHO has issued a guideline value of 25μg/L bromate for drinking waters. Both the European Union and USEPA have established a maximum level of 10μg/L bromate in drinking water. A novel method for the determination of trace bromote in water with GC-ECD is developed. The conditions of derivatization with acetylacetone are studied in detail. Under the optimal conditions, a good linear relationship (R2=0.9954) between the bromate concentrations (3.8~92μg/L) and the peak-areas of the bromo-derivate is obtained. The detection limit (MDL) of this method is 0.75μg/L. The average recovery rates for the samples are 105.1%~107.6% with relative standard deviation (RSD) less than 5%. With respect to the examination of the bromate in the filtrated surface water after ozonation, the natural organic matters would have less negative effect on the examination, provided that the ozone dose is higher than 0.8mg/mg DOC under the normal ozonation time.Compared with ozonation alone, the catalytic ozonation with metal oxides can reduce the bromate production. Among the catalysts studied, FeOOH shows the most significant activity during catalytic ozonation in reducing the production of bromate. During the 30 minutes'ozonation of the ultrapure water spiked with bromide, the sum of bromine in Br-, HOBr/BrO-, and BrO3- was lower than the total bromine introduced indicating that other bromine species might exist in the reaction..In both O3/FeOOH and ozonation alone, the bromate formation increases with the increase of ozone dose, bromide concentration, and pH. The yield of bromate increases with the alkalinity in the low bicarbonate concentration range for both of the two oxidation procedures. As the concentration increases further, the yield of bromate in ozonation alone reaches a steady state, while that in O3/FeOOH decreases. Under all the applied conditions, the O3/FeOOH shows a significant advantage over ozonatin alone in reducing the yield of bromate. There...