Tastes and odors (T&Os) of drinking water have been a major issue for water utilities in Korea, due to the ever-increasing consumers' demand on drinking water quality and complaints on T&Os. Among the T&Os causing chemicals in water, the most common and problematic ones are geosmin and 2-MIB, which are produced by blue–green algae and actinomycetes. The odors of the chemicals are characterized earthy and musty/camphorous. Since the reported odor thresholds of geosmin and 2-MIB are as low as 4.0 and 8.5 ng/L, respectively, they are not readily removed by conventional water treatment processes or by simple ozonation. Therefore, oxidation of the chemicals using hydrogen peroxide (H2O2) along with ozone (O3) has been tried as an alternative. In this study, kinetics of geosmin and 2-MIB ozonation at different initial O3 doses, H2O2/O3 ratios, and temperatures were evaluated. In short, a significant promotion of geosmin and 2-MIB ozonation rate was observed at higher H2O2/O3 ratios at lower temperature; therefore, geosmin and 2-MIB could be successfully removed from water. However, when an ozonation process is designed ozone residual should be considered for satisfactory disinfection; H2O2 addition may promote O3 decomposition and may have an adverse effect on disinfection. Therefore, determination of H2O2 and O3 doses should be carefully made for achieving both disinfection and T&Os removal.

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