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Issue 1, 2017
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Impact of environmental conditions on bacterial photoreactivation in wastewater effluents

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Abstract

Photoreactivation is a process where ultraviolet (UV)-induced damage to the DNA of microorganisms can be reversed by exposure to near UV and visible light. To date, most photoreactivation experiments have been carried out under laboratory conditions using standard microorganisms that do not reflect the natural conditions of municipal wastewater effluents. Photoreactivation could increase the concentration of pathogens released into natural systems, leading to negative impacts on fish, shellfish, and clams. In addition, pathogen release can increase health risks of downstream activities, such as swimming. This study focused on the photoreactivation of total coliforms in municipal wastewater effluents under natural sunlight conditions. The concept of ‘effective reactivation fluence’ (ERF) is used to evaluate and normalize the results from various light sources for a direct comparison. ERF values higher than 30 J cm−2, in conjunction with lowered nutrient concentrations (dilution of effluents with river water), decreased the photoreactivation of total coliforms. In contrast, higher temperatures (up to 25 °C) and blocking the UV-B portion of natural sunlight using a polyethylene terephthalate (PET) bottle increased their photoreactivation. The results of this research will provide guidance to wastewater plant operators on the potential need to minimize the level of photoreactivation in effluents before the effluents were released into receiving water bodies.

Graphical abstract: Impact of environmental conditions on bacterial photoreactivation in wastewater effluents

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Publication details

The article was received on 12 Sep 2016, accepted on 13 Dec 2016 and first published on 14 Dec 2016


Article type: Paper
DOI: 10.1039/C6EM00501B
Citation: Environ. Sci.: Processes Impacts, 2017,19, 31-37
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    Impact of environmental conditions on bacterial photoreactivation in wastewater effluents

    S. Shafaei, N. Klamerth, Y. Zhang, K. McPhedran, J. R. Bolton and M. Gamal El-Din, Environ. Sci.: Processes Impacts, 2017, 19, 31
    DOI: 10.1039/C6EM00501B

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