AWWA WQTC64063

The use of ultraviolet (UV) light at low doses for disinfection of a wide array of pathogens is well proven. Also, UV light at higher doses coupled with peroxide addition has been shown to generate hydroxyl radicals and oxidize taste and odor compounds. In the past, these two processes have been mutually exclusive because of the costs associated with different levels of UV light needed for disinfection compared to oxidation. However, recently UV equipment manufacturers have developed dual purpose UV systems that, when sized appropriately, have the flexibility to operate in "disinfection" mode during the most of the year and in "advanced oxidation" mode during the taste and odor season to oxidize taste and odor compounds. Across the United States, taste and odor events have been the focus of public attention for one water utility. Several water utilities are currently evaluating the dual purpose UV equipment as one option to oxidize taste and odor and do not understand the differences between UV disinfection and UV advanced oxidation (UV/AOP) for taste and odor destruction. This paper describes the following items: mechanisms of UV/AOP for taste and odor reduction; factors affecting UV/AOP performance; the differences between UV disinfection and UV/AOP for taste and odor oxidation; the terminology used with both technologies; the previous evaluations and number of utilities using UV/AOP technology; the feasibility of using UV light and peroxide for oxidation of taste and odor compounds; a cost comparison of UV disinfection versus advanced oxidation of taste and odor compounds; and, conclusions and recommendations for water utilities considering UV/AOP for taste and odor control. Includes 14 references, tables, figures.