PHOTOCATALYTICALLY-MEDIATED DISINFECTION OF WATER USING TIO2 AS A CATALYST AND SPORE-FORMINGSPORE-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 viabil ity of B. pumilus spores, suspended with TiO2 in water, was observed a fter exposing the model organism to ultraviolet (UV) light (lambda 365 nm). Kinetic plots showed that the viability of B. pumilus sports dec reased exponentially. No reduction in viability occurred if B. pumilus spores were incubated in the dark (control) or if illumination occurr ed in the absence of a TiO2 catalyst (TiO2 condition). Intermittent il lumination reduced viable B. pumilus spores more effectively than cont inuous exposure to UV. For various TiO2 concentrations suspended in wa ter 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 phot ocatalytic process shows significant potential as a basis for both sta tionary and portable water disinfecting devices.