When ozone is used as a primary disinfectant, which byproducts may form that require monitoring?

When ozone is used as a primary disinfectant, which byproducts may form that require monitoring?

• A. chlorate and chlorite production
• B. haloacetic acids formation
• C. bromate and formaldehyde production
• D. bromate and chlorite formation

Answer: (C)

When ozone is used as the primary disinfectant, the main byproducts to monitor are bromate and formaldehyde. Bromate can form when ozone oxidizes bromide that may be present in the source water, especially with higher ozone doses or longer contact times, and it is a regulated concern. Formaldehyde forms from ozonation of natural organic matter, producing aldehydes like formaldehyde, again more likely under higher ozone doses and longer contact times. The other options point to byproducts associated with chlorine-based processes or different reaction pathways, not the direct byproducts of ozone disinfection.

When ozone is used as the primary disinfectant, the main byproducts to monitor are bromate and formaldehyde. Bromate can form when ozone oxidizes bromide that may be present in the source water, especially with higher ozone doses or longer contact times, and it is a regulated concern. Formaldehyde forms from ozonation of natural organic matter, producing aldehydes like formaldehyde, again more likely under higher ozone doses and longer contact times. The other options point to byproducts associated with chlorine-based processes or different reaction pathways, not the direct byproducts of ozone disinfection.