Photocatalytic Degradation of Taste and Odour Causing Compounds in Natural Water Sources

The aesthetic quality of drinking water from surface water sources is often compromised by the presence of odour causing compounds, (particularly geosmin and MIB. These compounds are a major concern in the drinking water industry in South Africa and globally. They lower the potability of the water and may serve as precursors of carcinogenic disinfection byproducts (DBPs during disinfection. Taste and odour causing compounds have been shown to survive conventional treatment unit operations such as sedimentation and filtration. This study highlights the optimisation of a photocatalytic system of irradiated anatase titanium dioxide for the degradation of geosmin at environmentally significant levels obtained from the analysis of source waters of the Rietvlei and Roodeplaat Water Treatment Plants supplying drinking water to the capital city of Pretoria and its environs. Effect of UV radiance flux on the degradation efficiency was evaluated using a low pressure 9 W lamp and a medium pressure 400 W UV lamp. Photocatalytic degradation was carried out with a TiO(2)/UV batch system using both lamps. Effect of catalyst concentration on the process was also evaluated over a wide range of TiO(2) concentrations. Complete degradation of environmentally significant levels of geosmin was achieved with the photocatalytic system (medium pressure UV and catalyst concentration of 60 mg/l within 40 minutes. of treatment with initial degradation rates of 14.8 ng/l.min(-1). The results of the study for the degradation of geosmin is very encouraging and can be adopted for the treatment of other taste and odour compounds like 2-MIB and 2,4,6-TCA