Pilot testing and engineering application of O3/H2O2 process for 2-methylisoborneol and geosmin removal in drinking water treatment

Microorganisms in source water, including algae, actinomycetes and other microbes, produce secondary metabolites during growth, particularly 2-methylisoborneol (2-MIB) and geosmin (GSM), which emerge as the primary contributors to taste and odor issues in drinking water. Although the conventional ozone (O3) oxidation process has been widely adopted to address the odor issue, it frequently exhibits inadequate removal efficiency for 2-MIB and GSM, and presents the risk of bromate formation exceeding regulation limit when processing bromine-enriched water. In this study, a pilot study applying the O3/H2O2 advanced oxidation process (AOP) was conducted to overcome the above problems. The influence of variables, including O3 dosage, O3/H2O2 ratio, etc., on the removal efficiency of 2-MIB, GSM, natural organic matter as the permanganate index (PI), and bromate formation was investigated, and compared with the conventional ozonation process. According to the pilot-scale experiments, the O3/H2O2 AOP demonstrated remarkable efficacy in effectively eliminating odorous substances and inhibiting bromate formation. The full-scale application of the O3/H2O2 AOP at a 120,000 m3/d water plant in Shandong, China also showed that while the 2-MIB and GSM concentrations in raw water were up to 260 and 33 ng/L, respectively, the treated water had 2-MIB and GSM concentrations <10 ng/L, which fulfills the “Standards for Drinking Water Quality” of China (GB 5749-2022). Meanwhile, bromate remained undetectable.