Recent Research on Ozonation By-products in Water and Wastewater Treatment: Formation, Control, Mitigation, and Other Relevant Topics

Abstract

Ozone is a powerful oxidant and disinfectant widely used in water and wastewater treatment. Unlike chlorine, ozone does not produce chlorinated and brominated organic disinfection by-products, such as trihalomethanes and haloacetic acids. However, ozone-based treatment produces its own disinfection by-products, namely bromate, nitrosamines (such as N-nitrosodimethylamine or NDMA), aldehydes, ketones, and carboxylic acids. According to the International Agency for Research on Cancer, bromate and NDMA have been classified as possibly carcinogenic to humans (Group 2B) and probably carcinogenic to humans (Group 2A), respectively. Because of its relevance in drinking water, bromate has been regulated in many countries as a primary drinking water contaminant. The formation and control of these compounds during water and wastewater treatment using ozone has been an active research topic in the water and wastewater industry. Recently, the use of ozone in advanced water purification and reuse has attracted much interest and is adding new aspects in ozonation-by product research. In this chapter, recent research on these ozonation by-products is reviewed. The emphasis will be given on two of the ozonation by-products, bromate and NDMA, because of their relevance in drinking water and recycled water and the difficulty of their complete removal/mitigation with currently available technologies.