Hn. Pham et al., QUANTITATIVE-ANALYSIS OF VARIATIONS IN INITIAL BACILLUS-PUMILUS SPOREDENSITIES IN AQUEOUS TIO2 SUSPENSION AND DESIGN OF A PHOTOCATALYTIC REACTOR, Journal of environmental science and health. Part A: Environmental science and engineering, 32(1), 1997, pp. 153-163
Spore-forming Bacillus pumilus was used as a model for TiO2-based phot
ocatalysis. Previous results have shown that for different initial spo
re densities between 10(4) and 10(10) CFU/ml, more inactivation of via
ble spores in aqueous TiO2 suspension occurred with an increase in spo
re density. The results were different from published results for diff
erent initial concentrations of organic pollutants and non-spore-formi
ng organisms (e.g., E. coli). To determine a plausible explanation for
the results obtained for the B. pumilus spores, a quantitative analys
is has been performed based on the theory of probability. Since hydrox
yl radicals (. OH) have been thought to be the primary species respons
ible for degrading/inactivating contaminants in water, a probabilistic
approach will be used to determine quantitatively the likelihood that
an interaction, or a collision, between a hydroxyl radical and a B. p
umilus spore will occur, or that a hydroxyl radical interacting with d
etermined based on this model, these theoretical values will be compar
ed to the experimental values obtained for each initial B. pumilus spo
re density. Also, a design of a simple photocatalytic reactor system-r
egardless of the amount of initial spore densities present-will be giv
en to determine parameters which could be used to scale-up to an engin
eering scale design.