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A comparison of the effectiveness of TiO2 photocatalysis and UVA photolysis for the destruction of three pathogenic micro-organisms.

Robertson, Jeanette M.C.; Robertson, Peter K.J.; Lawton, Linda A.

Authors

Jeanette M.C. Robertson

Peter K.J. Robertson



Abstract

TiO2 photocatalysis has demonstrated efficacy as a treatment process for water contaminated with chemical pollutants. When exposed to UVA light TiO2 also demonstrates an effective bactericidal activity. The mechanism of this process has been reported to involve attack by valence band generated hydroxyl radicals. In this study when three common bacterial pathogens, Escherichia coli, Salmonella enterica serovar Enteritidis and Pseudomonas aeruginosa, were exposed to TiO2 and UVA light a substantial decrease in bacterial numbers was observed. Control experiments in which all three pathogens were exposed to UVA light only resulted in a similar reduction in bacterial numbers. Moreover, exposure to UVA light alone resulted in the production of a smaller than average colony phenotype among the surviving bacteria, for all three pathogens examined, a finding which was not observed following treatment with UVA and TiO2. Small slow growing colonies have been described for several pathogenic bacteria and are referred to as small colony variants. Several studies have demonstrated an association between small colony variants and persistent, recurrent and antibiotic resistant infections. We propose that the production of small colony variants of pathogenic bacteria following UVA treatment of drinking water may represent a health hazard. As these small colony variants were not observed with the UVA/TiO2 system this potential hazard is not a risk when using this technology. It would also appear that the bactericidal mechanism is different with the UVA/TiO2 process compared to when UVA light is used alone.

Citation

ROBERTSON, J.M.C., ROBERTSON, P.K.J. and LAWTON, L.A. 2005. A comparison of the effectiveness of TiO2 photocatalysis and UVA photolysis for the destruction of three pathogenic micro-organisms. Journal of photochemistry and photobiology A: chemistry [online], 175(1), pages 51-56. Available from: https://doi.org/10.1016/j.jphotochem.2005.04.033

Journal Article Type Article
Acceptance Date Sep 30, 2005
Online Publication Date Sep 30, 2005
Publication Date Sep 30, 2005
Deposit Date Jul 2, 2010
Publicly Available Date Jul 2, 2010
Journal Journal of photochemistry and photobiology A: chemistry
Print ISSN 1010-6030
Publisher Elsevier
Peer Reviewed Peer Reviewed
Volume 175
Issue 1
Pages 51-56
DOI https://doi.org/10.1016/j.jphotochem.2005.04.033
Keywords UVA irradiation; Photocatalysis; TiO2; Pathogenic micro-organism; Small colony variants
Public URL http://hdl.handle.net/10059/494

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