The composition of the wastewater matrix influences the oxidation potential of ozonation, a technique widely recognized efficient removal of micropollutants. Here, we developed a chemical kinetic model to determine the ozone dose required to minimize bromate production in wastewater containing bromine ions while achieving target removal rates. In wastewater ozonation, ozone decomposition comprises instantaneous ozone consumption and subsequent decomposition at first-order reaction rates. Under the injection condition of 1.5 g O3/g dissolved organic carbon (DOC), the instantaneous ozone demand was 62.7% of the injection concentration, and it increased proportionally with increasing injected ozone concentration. Ozone and hydroxyl radical exposures were proportional to the initial ozone dose, while hydroxyl radical exposure was proportional to ozone exposure, and the deviation was relatively high at 1.0-1.5 g O3/g DOC. The calculated hydroxyl radical exposure was 3.0 × 10-10 to 5.3 × 10-10 M s. Ozone and hydroxyl radicals are highly correlated with the ratio of ozone dose to organic matter concentration. Therefore, a trace substance removal rate evaluation model combined with the ROH, O3 model and a bromate generation model were also considered. For ibuprofen, the ozone dose for achieving the target removal rate of 80% while maintaining the bromate concentration below 50 μg L-1 was suitable in the operating range of 0.86 g O3/g DOC or more. The proposed method provides a practical operation strategy to calculate the appropriate ozone dose condition from the target compound removal rate prediction and bromate generation models considering the ratio of ozone dose to organic matter concentration in the incoming wastewater.
Keywords: Bromide; Micropollutants; Ozonation; Specific ozone dose; Wastewater.
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