PHOTOCATALYTICALLY-MEDIATED DISINFECTION OF WATER USING TIO2 AS A CATALYST AND SPORE-FORMING BACILLUS-PUMILUS AS A MODEL

The photocatalytic oxidation process has been evaluated as a basis for disinfecting large volumes of water. A 95 percent reduction in viability of B. pumilus spores, suspended with TiO2 in water, was observed after exposing the model organism to ultraviolet (UV) light (lambda 365 nm). Kinetic plots showed that the viability of B. pumilus sports decreased exponentially. No reduction in viability occurred if B. pumilus spores were incubated in the dark (control) or if illumination occurred in the absence of a TiO2 catalyst (TiO2 condition). Intermittent illumination reduced viable B. pumilus spores more effectively than continuous exposure to UV. For various TiO2 concentrations suspended in water from 1 mg/ml to 4 mg/ml, maximum losses of viability were observed at TiO2 concentrations of 2 mg/ml of water and spore densities > 10(9) CFU/ml. On the basis of the data presented here, the TiO2-based photocatalytic process shows significant potential as a basis for both stationary and portable water disinfecting devices.