AWWA WQTC58834

A survey conducted in more than 800 utilities in the United States and Canada had found that 16% of the utilities experience serious taste and odor problems. The earthy and musty odor in surface water is frequently caused by 2- methyisoborneol (MIB) and Geosmin. These compounds are produced by blue green algae or actinomycetes metabolites and can be detected in drinking water at very low concentrations (Gerber 1965; Rosen 1970; Suffet et al. 1995). The threshold concentration for detecting these compounds depends on the taste and odor sensitivity of the individual and it varies from about 6-10 ng/L (Meng and Suffet 1997; Rashash et al. 1997; Wnorowski 1992). Incorporating processes in water treatment plants that effectively remove MIB and Geosmin should also achieve other treatment goals such as microbial or disinfection byproduct (DBP) control. Activated carbon processes are commonly used to remove MIB and Geosmin, but some oxidation processes are also quite effective (Bruce et al. 2002; Graham et al. 2000). Past studies focused primarily on ozone dose and percentage MIB or Geosmin removal. This paper focuses on the mechanisms and kinetics of MIB and Geosmin oxidation. Although ozonation is very effective in removing MIB and Geosmin, the lack of information on oxidation mechanisms (O3 vs OHA radicals) prevents optimization of ozone for taste and odor control, DBP control and microbial control. The goal of this paper is to understand the relative importance of O3 and HOA oxidation pathways and rate constants for MIB and Geosmin. Kinetics were evaluated for MIB and Geosmin oxidation by ozone in natural waters with a range of water qualities. Effects of various treatment process parameters (ozone dose, pH, H2O2) and water quality parameters (temperature, initial MIB concentration) were evaluated. Additional treatment considerations (BDOC formation, bromate control and microbial inactivation) were evaluated in light of achieving MIB and Geosmin removal. Includes 31 references, figures.