BACTERICIDAL ACTIVITY OF TIO2 PHOTOCATALYST IN AQUEOUS-MEDIA - TOWARDA SOLAR-ASSISTED WATER DISINFECTION SYSTEM

Irradiation of suspensions of Escherichia Coli (approximately 10(6) ce lls/mL) and TiO2 (anatase) with UV-visible light of wavelengths longer than 380 nm resulted in the killing of the bacteria within minutes. O xygen was found to be a prerequisite for the bactericidal properties o f the photocatalyst. Bacterial killing was found to adhere to first-or der kinetics. The rate constant was proportional to the square root of the concentration of TiO2 and proportional to the incident light inte nsity in the range approximately 180-approximately 1660 muE s-1 m-2. T he trends in these simulated laboratory experiments were mimicked by o utdoor tests conducted under the summer noonday sun in Texas. The impl ications of these results as well as those of previous investigations in terms of practical applicability to solar-assisted water treatment and disinfection at remote sites are discussed relative to water techn ologies currently considered as viable alternatives to chlorination.