Photocatalytic-based inactivation of E. coli by UV 282 nm XeBr Excilamp

Abstract

The impact of suspended TiO₂ particles on the efficiency of UV inactivation of E. coli by XeBr excilamp (282 nm) was assessed using direct and integrating sphere spectroscopy for absorbance measurements in the calculations of UV doses. Complete disinfection (no quantifiable E. coli colonies) was observed at 30 (0.25 g/L of TiO₂) and 40 mJ/cm² (0.1 g/L of TiO₂), whereas UV alone and the treatment in the presence of 0.5 g/L of TiO₂ produced tailing in the dose-response curves. The optimum concentration of TiO₂ was found to be 0.25 g/L, which correlates with the highest •OH exposure (CT value) and steady state concentration of •OH. This study demonstrates the importance of proper calculation of UV dose and inclusion of •OH exposure effects when reporting results from disinfection studies using technologies with multiple modes of inactivation such as with UV/TiO₂.

Keywords:

• Ultraviolet excilamp
• water disinfection
• titanium dioxide particles
• scattering

Acknowledgments

The authors gratefully acknowledge the Fulbright Program for financial support to Dr. Galina Matafonova, who was a Fulbright Visiting Scholar at the University of Colorado at Boulder at the time of this research. The authors also thank Dr. Aaron Dotson, Mrs. Olya Keen, and Ms. Sarah Bounty for their advice in disinfection experiments.