Pilot scale evaluation of ozone versus peroxone for trihalomethane and bromate production

A pilot plant located at the A. H. Weeks Water Treatment Plant in Windsor, ON was used to investigate the effects of peroxone (hydrogen peroxide + ozone) versus ozone on bromate and trihalomethane formation. The raw water source used in this study was the Detroit River. The peroxide dose was varied while ozone dose remained constant. The effect of adding peroxide prior to ozonation and after ozonation was investigated. The raw water bromide concentrations ranged between 12 and 47 mug/L.; The system in which peroxide was added after ozonation, the trihalomethane concentrations were found to be up to 46% higher compared to the ozone only system. In addition, increasing the hydrogen peroxide/ozone ratio from 0.1 to 0.35, led to an increase in trihalomethane concentrations from 5.1 mug/L to 9.1 mug/L, respectively. In terms of bromate formation, peroxone (post-ozonation) was able to reduce bromate concentration by 33% on average, compared to ozone. However, as the peroxide dose was increased the bromate formation also increased, from 6.0 mug/L to 10.5 mug/L for ratios of 0.1 and 0.35 respectively, although these values were still lower than that of the ozone samples. (Abstract shortened by UMI.)...