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Effect of Environmental Factors on Photoreactivation of Microorganisms under Indoor Conditions

Authors: Shirin Shafaei, James R. Bolton, Mohamed Gamal El Din


Ultraviolet (UV) disinfection causes damage to the DNA or RNA of microorganisms, but many microorganisms can repair this damage after exposure to near-UV or visible wavelengths (310–480 nm) by a mechanism called photoreactivation. Photoreactivation is gaining more attention because it can reduce the efficiency of UV disinfection of wastewater several hours after treatment. The focus of many photoreactivation research activities on the single species has caused a considerable lack in knowledge about complex natural communities of microorganisms and their response to UV treatment. In this research, photoreactivation experiments were carried out on the influent of the UV disinfection unit at a municipal wastewater treatment plant (WWTP) in Edmonton, Alberta after exposure to a Medium-Pressure (MP) UV lamp system to evaluate the effect of environmental factors on photoreactivation of microorganisms in the actual municipal wastewater. The effect of reactivation fluence, temperature, and river water on photoreactivation of total coliforms was examined under indoor conditions. The results showed that higher effective reactivation fluence values (up to 20 J/cm2) and higher temperatures (up to 25 °C) increased the photoreactivation of total coliforms. However, increasing the percentage of river in the mixtures of the effluent and river water decreased the photoreactivation of the mixtures. The results of this research can help the municipal wastewater treatment industry to examine the environmental effects of discharging their effluents into receiving waters.

Keywords: temperature, river water, photoreactivation, reactivation fluence, ultraviolet disinfection, wastewater effluent

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[1] C. Hallmich, R. Gehr, "Effect of pre- and post-UV disinfection conditions on photoreactivation of fecal coliforms in wastewater effluents," Water Research, vol. 44, 2885-2893, 2010
[2] M. Guo, H. Hu, J. R. Bolton, M. Gamal El-Din, "Comparison of low- and medium-pressure ultraviolet lamps: Photoreactivation of Escherichia coli and total coliforms in secondary effluents of municipal wastewater treatment plants," Water Research, vol. 43, 815-821, 2009
[3] C. Shang, L. M. Cheung, C. M. Ho, and M. Zeng, "Repression of photoreactivation and dark repair of coliform bacteria by TiO2-modified UV-C disinfection," Applied Catalysis. B: Environmental, vol. 89, pp. 536-542, 2009
[4] J. Süß, S. Volz, U. Obst, and T. Schwartz, "Application of a molecular biology concept for the detection of DNA damage and repair during UV disinfection," Water Research, vol. 43, pp. 3705-3716, 2009
[5] Z. Bohrerova, K. G. Linden, "Standardizing photoreactivation: Comparison of DNA photorepair rate in Escherichia coli using four different fluorescent lamps," Water Research, vol. 41, pp. 2832-2838, 2007
[6] A. Locas, J. Demers, P. Payment, "Evaluation of photoreactivation of Escherichia coli and enterococci after UV disinfection of municipal wastewater," Canadian Journal of Microbiology, vol. 54 (11), pp. 971-975, 2008
[7] Y. Y. Chan, E. G. Killick, "The effect of salinity, light and temperature in a disposal environment on the recovery of E. coli following exposure to ultraviolet radiation," Water Research, vol. 29, pp.1373-1377, 1995
[8] I. Salcedo, J. A. Andrade, J. M. Quiroga, and E. Nebot, "Photoreactivation and dark repair in UV-treated microorganisms: effect of temperature," Applied and Environmental Microbiology, vol. 73 (5), pp.1594-1600, 2007
[9] I. Arana, A. Muela, J. Iriberri, L. Egea, and I. Barcina, "Role of hydrogen peroxide in loss of culturability mediated by visible light in Escherichia coli in a freshwater ecosystem," Applied and Environmental Microbiology, vol. 58(12), pp. 3903-3907, 1992
[10] L. W. Sinton, R. J. Davies-Colley, and R. B. Bell, "Inactivation of enterococci and fecal coliforms from sewage and meatworks effluents in seawater chambers," Applied and Environmental Microbiology, vol. 60 (6), pp. 2040-2048, 1994
[11] M. Takao, A. Oikawa, A.P. Eker, A. Yasui, “Expression of an anacystis nidulans phoyolyase gene in Escherichia coli; functional complementation and modified action spectrum of photoreactivation,” Photochemistry and Photobiology, vol. 50(5), pp. 633-637, 1989
[12] APHA, AWWA, WEF, "Standard Methods for the Examination of Water and Wastewater," Washington, D.C. : America Public Health Association, 2005
[13] J. R. Bolton, K. G. Linden, "Standardization of methods for fluence (UV dose) determination in bench-scale UV experiments," Journal of Environmental Engineering-ASCE, vol. 129, pp. 209-215, 2003
[14] K. G. Lindenauer, J. L. Darby, "Ultraviolet disinfection of wastewater: effect of dose on subsequent photoreactivation," Water Research, vol. 28 (4), pp. 805-817, 1994
[15] G. B. Sancar, "Enzymatic photoreactivation: 50 years and counting," Mutation Research, vol. 451, pp. 25-37, 2000
[16] K. Malhotra, S. T. Kim, C. Walshg, and A. Sancar, "Roles of FAD and 8-hydroxy-5-deazaflavin chromophores in photoreactivation by Anucystis niduluns DNA photolyase," The Journal of Biological Chemistry, vol. 267(22), pp.15406-15411, 1992
[17] J. Brazard, A. Usman, F. Lacombat, C. Ley, M. M. Martin, P. Plaza, L. Mony, M. Heijde, G. Zabulon, and C. Bowler, "Spectro-temporal characterization of the photoactivation mechanism of two new oxidized cryptochrome/photolyase photoreceptors," Journal of the American Chemical Society, vol.132, pp. 4935-4945, 2010
[18] G. J. Herndl, A. Brugger, S. Hager, E. Kaiser, I. Obernosterer, B. Reitner, and D. Slezak, "Role of ultraviolet-B radiation on bacterioplankton and the availability of dissolved organic matter," Vegetation, vol. 128, pp. 43-51, 1997
[19] R. P. Sinha, D. P. Häder, UV-induced DNA damage and repair: a review," Photochemical and Photobiological Sciences, vol. 1, pp. 225-236, 2002
[20] F. Bosshard, M. Bucheli, Y. Meur, and T. Egli, "The respiratory chain is the cell’s Achilles’ heel during UVA inactivation in Escherichia coli," Microbiology, vol. 156, pp. 2008-2015, 2010