Medium‐Pressure UV/Chlorine Advanced Oxidation of Taste and Odor Compounds

Installations of medium‐pressure ultraviolet (UV) disinfection systems continue to increase, and some systems have excess dose capacity that could potentially be used for a low‐level advanced oxidation process (AOP). While UV/hydrogen peroxide has been commonly used in advanced oxidation applications, UV/chlorine (Cl 2 ) is much less understood and may have limited applications for some of these systems. This work investigates the role of Cl 2 residual, pH, alkalinity, and nitrate on this AOP and the performance that can be achieved at conditions typical to drinking water treatment plants. Results show that a 40–60% reduction of 2‐methylisoborneol and geosmin could be achieved with ambient water quality conditions by adding Cl 2 and significantly increasing the applied UV energy to several hundred mJ/cm 2 MS2 reduction equivalent dose, potentially bringing these compounds below the odor threshold. Experiments with the addition of nitrate demonstrate that it can also serve as a radical generator in waters containing low levels of nitrate.