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

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/cm(2) (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.