AWWA WQTC58834

AWWA WQTC58834 Oxidation of MIB and Geosmin by Ozone and Hydroxyl Radicals
Conference Proceeding by American Water Works Association, 11/02/2003

Westerhoff, Paul; Nair, Brijesh; Pei, Peng

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A survey conducted in more than 800 utilities in the United States and Canadahad 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 oractinomycetes metabolites and can be detected in drinking water at very lowconcentrations (Gerber 1965; Rosen 1970; Suffet et al. 1995). The thresholdconcentration for detecting these compounds depends on the taste and odor sensitivity ofthe 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 thateffectively remove MIB and Geosmin should also achieve other treatment goals such asmicrobial or disinfection byproduct (DBP) control.Activated carbon processes are commonly used to remove MIB and Geosmin, butsome oxidation processes are also quite effective (Bruce et al. 2002; Graham et al. 2000). Past studies focused primarily on ozone dose and percentageMIB or Geosmin removal. This paper focuses on the mechanisms and kineticsof MIB and Geosmin oxidation. Although ozonation is very effective in removing MIB and Geosmin, the lack ofinformation on oxidation mechanisms (O3 vs OHA radicals) prevents optimization ofozone for taste and odor control, DBP control and microbial control. The goal of thispaper is to understand the relative importance of O3 and HOA oxidation pathways and rateconstants for MIB and Geosmin. Kinetics were evaluated for MIB and Geosminoxidation by ozone in natural waters with a range of water qualities. Effects of varioustreatment process parameters (ozone dose, pH, H2O2) and water quality parameters(temperature, initial MIB concentration) were evaluated. Additional treatmentconsiderations (BDOC formation, bromate control and microbial inactivation) wereevaluated in light of achieving MIB and Geosmin removal. Includes 31 references, figures.