Parameters Influencing the Photocatalytic Degradation of Geosmin and 2-Methylisoborneol Utilizing Immobilized TiO2

Abstract

Geosmin and 2-methylisoborneol (MIB) are taste and odor compounds that negatively impact potable water and freshwater aquaculture species. Conventional water treatment methods are generally ineffective for the removal of these compounds. Prior studies using TiO2 photocatalysts have shown promising results, but are primarily limited to laboratory scale batch slurry systems. Immobilization of TiO2 is essential for the effective scale-up and conversion to a flow through system. In this study, the degradation of MIB and geosmin from laboratory spiked and naturally tainted water samples was demonstrated utilizing an immobilized TiO2 photocatalyst. The benefits of TiO2 photocatalysis, in comparison to photolysis, are discussed. Further, the influence of pH on the degradation rates was analyzed to optimize process location in an aquaculture production facility. Geosmin degradation reached a maximum near a pH of 6. While MIB degradation is highest at low pH, there is an inflection in this trend above the pH at which TiO2 has a zero surface charge. Photocatalytic processing is recommended to occur after nitrification and before base addition to maximize MIB and geosmin removal rates. The findings of this work have been incorporated into a larger project, which assesses the continuous operation of TiO2 photocatalyst in a recirculating aquaculture system.