Repression of photoreactivation and dark repair of coliform bacteria by TiO2-modified UV-C disinfection

Autor: Chii Shang, Chiu-Man Ho, Minzhen Zeng, Lok Man Cheung
Rok vydání: 2009
Předmět:
Zdroj: Applied Catalysis B: Environmental. 89:536-542
ISSN: 0926-3373
DOI: 10.1016/j.apcatb.2009.01.020
Popis: Photoreactivation and dark repair of damaged DNA can occur after some bacteria are disinfected with UV-C irradiation and thus reduce the disinfection efficiency. We have discovered that the provision of 1 mg/L titanium dioxide (TiO 2 ) in suspension during UV-C irradiation at normal disinfection doses repressed the photoreactivation and dark repair. The repressive effect was also observed when a TiO 2 -coated plate was used during UV-C exposure but removed thereafter, indicating the repressive effect does not require the presence of TiO 2 in the post-UV event. The repressive effect was consistently observed with changes of bacteria species, temperature, salinities, UV sources, doses and intensities, and with/without nutrients. The repressive effect is likely associated with the additional radical attack during UV-TiO 2 irradiation and/or formation of a small amount of stable residual oxidants (primarily hydrogen peroxide). The TiO 2 -modified UV-C disinfection represents an innovative means to disinfect water. It is particularly useful in situations where additions of residual chlorine or chloramines are not allowed or not possible. Nevertheless, the TiO 2 shall be properly included, by either using the optimum dose in suspension or immobilizing it onto a surface, since too little TiO 2 cannot provide the repression while too much TiO 2 in suspension gives a detrimental effect on the UV-C disinfection.
Databáze: OpenAIRE
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