Photocatalytic sterilization of water by a tubular UV/T_IO₂ film reactor

Abstract

Photocatalytic sterilization of microorganisms in water was conducted with a tubular UV/T_iO₂ film reactor (SS304, 2.5 inches in diameter, 14 inches in length, and 0.65 L in effective volume) containing a 14 W low pressure mercury vapor lamp as an UV irradiation source with a maximum intensity at 254 nm, which was placed at the center of the reactor chamber. It was found that the number of E. coli was significantly declined from 1.5^*10⁷ CFU/100 mL to 270 CFU/100 mL after 5 seconds treatment with the tubular UV/T_iO₂ film reactor, while the survival of E. coli remained 1.3^*10⁴ CFU/100 mL for a similar commercial UV water sterilizer. In addition, the required I*t value (UV light intensity * irradiation time) for three log reduction of E. coli were 6.608 and 10.238 mW/cm^2.s for a tubular UV/T_iO₂ film reactor and a similar commercial UV water sterilizer, respectively. On the other hand, results indicated that the higher the TSS concentration, the lower the sterilization rate for both UV and UV/T_iO₂ film reactors, and the adverse effect due to the presence of SS was more pronounced for UV/T_iO₂ film reactor than for UV reactor. However, according to the higher sterilization rate, it was still suggested that a tubular UV/T_iO₂ film reactor could be considered as a better alternative for water sterilization.

Key words:

• Photocatalytic sterilization
• UV
• T_iO₂
• E. coli