AWWA WQTC64067

UV/H₂O₂ advanced oxidation of drinking water for taste and odor control was performed at pilot- and bench-scale using natural surface waters to optimize treatment conditions and monitor the effects on chlorine decay, chloramine decay, and disinfection byproduct formation. The pilot study demonstrated that the optimal dose of hydrogen peroxide for the removal of two taste and odor compounds (geosmin and MIB) was 6-10 mg/L. From bench-scale simulated distribution system tests, both ultraviolet (UV) alone (at an estimated dose of 10000 mJ/cm²) and UV/H₂O₂ resulted in significantly lower levels of chlorine residual compared to the control. The effects of the level of advanced oxidation applied on the chlorine residual were water-specific, with both increasing and decreasing trends. Similar results were observed for chloramine decay in natural surface waters, although decreases in chloramine decay were much less significant than with chlorine. Effects of advanced oxidation on disinfection byproducts (DBPs) were also water-specific. THMs increased with the application of UV or UV/H₂O₂ in two of three water samples, while in one sample, trihalomethanes (THMs) increased at lower levels of advanced oxidation and decreased with higher levels of advanced oxidation or with high doses of UV alone. Haloacetic Acids (HAAs) decreased significantly (by up to 138 µg/L) with the application of UV or UV/H₂O₂ in two samples, but increased slightly (25 µg/L or less) following advanced oxidation in the third water sample. Results from this research highlight the importance of performing comprehensive site-specific evaluations when establishing the feasibility of using UV/H₂O₂ for taste and odor control, since apparently it may have a significant impact on secondary disinfectant stability and DBP formation in the distribution system in some waters. Includes 8 references, figures.