Current address: Ding Wang, Department of Civil Engineering, University of Toronto, Toronto, ON M5S 1A4, Canada.
Comparison of the Disinfection Effects of Vacuum-UV (VUV) and UV Light on Bacillus subtilis Spores in Aqueous Suspensions at 172, 222 and 254 nm
Article first published online: 12 NOV 2009
© 2009 The Authors. Journal Compilation. The American Society of Photobiology
Photochemistry and Photobiology
Volume 86, Issue 1, pages 176–181, January/February 2010
How to Cite
Wang, D., Oppenländer, T., El-Din, M. G. and Bolton, J. R. (2010), Comparison of the Disinfection Effects of Vacuum-UV (VUV) and UV Light on Bacillus subtilis Spores in Aqueous Suspensions at 172, 222 and 254 nm. Photochemistry and Photobiology, 86: 176–181. doi: 10.1111/j.1751-1097.2009.00640.x
- Issue published online: 4 JAN 2010
- Article first published online: 12 NOV 2009
- Received 17 June 2009, accepted 27 August 2009
The efficacy of UV and vacuum-UV (VUV) disinfection of Bacillus subtilis spores in aqueous suspensions at wavelengths of 172, 222 and 254 nm was evaluated. A Xe2* excilamp, a KrCl* excilamp and a low-pressure mercury lamp were used as almost monochromatic light sources at these three wavelengths. The first-order inactivation rate constants at 172, 222 and 254 nm were 0.0023, 0.122 and 0.069 cm2 mJ−1, respectively. Therefore, a 2 log reduction of B. subtilis spores was reached with fluences (UV doses) of 870, 21.6 and 40.4 mJ cm−2 at these individual wavelengths. Consequently, for the inactivation of B. subtilis spores, VUV exposure at 172 nm is much less efficient than exposure at the other two wavelengths, while exposure at 222 nm is more efficient than that at 254 nm, which is probably because triplet energy transfer from DPA to thymine bases at 222 nm is higher than that at 254 nm. This research indicated quantitatively that VUV light is not practicable for microorganism disinfection in water and wastewater treatment. However, in comparison with other advanced oxidation processes (e.g. UV/TiO2, UV/H2O2 or O3/H2O2) the VUV-initiated photolysis of water is likely more efficient in generating hydroxyl radicals and more effective for the inactivation of microorganisms.