Evaluation of Photocatalytic Sterilization Rates of Escherichia coli Cells in Titanium Dioxide Slurry Irradiated with Various Light Sources
Photocatalytic sterilization of <I>Escherichia coli</I> cells with TiO<SUB>2</SUB> particles is examined using a rectangular bubble-column reactor irradiated with three kinds of artificial light sources. The three types of used lamps were a black light fluorescent (BL-F) lamp, a blue actinic fluorescent (BA-F) lamp and a daylight fluorescent (DL-F) lamp. Under the conditions of TiO<SUB>2</SUB> concentration of 1 × 10<SUP>–2</SUP> kg/m<SUP>3</SUP> and initial cell concentration of 1 × 10<SUP>11</SUP> cells/m<SUP>3</SUP>, average light intensities in the reactor were varied in the range of 0 to 22 W/m<SUP>2</SUP>, 0 to 14 W/m<SUP>2</SUP> and 0 to 1.1 W/m<SUP>2</SUP> with the BL-F, BA-F and DL-F lamps, respectively. The apparent sterilization rate constants of <I>E. coli</I> cells for these lamps are determined on the basis of a series-event model, and are compared with those obtained in experiments with a high pressure mercury lamp. Irrespective of the examined lamps, the rate constants can be correlated with the light quantities absorbed by TiO<SUB>2</SUB> slurry, which are evaluated by taking into account both the dependency of absorbance of TiO<SUB>2</SUB> slurry on light wavelengths and the spectral distributions of light rays from the respective lamps. From the results obtained in experiments using the artificial light sources, the sterilization rate constants of <I>E. coli</I> under the sunlight can be predicted. The experimental data are in good agreement with the predicted results in the reactor illuminated with sunlight at average light intensities of 14 and 23 W/m<SUP>2</SUP>.
- Journal of chemical engineering of Japan
Journal of chemical engineering of Japan 31(4), 577-584, 1998-08
The Society of Chemical Engineers, Japan