title: Impact of environmental conditions on bacterial photoreactivation in wastewater effluents.
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.
authors.affiliation: 7-285 Donadeo Innovation Centre for Engineering, Environmental Engineering Program, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada. mgamalel-din@ualberta.ca.
authors.forename: Shirin
authors.initials: S
authors.lastname: Shafaei
authors.affiliation: 7-285 Donadeo Innovation Centre for Engineering, Environmental Engineering Program, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada. mgamalel-din@ualberta.ca and Department of Hydrogeology, Freiberg University of Mining and Technology, Freiberg, Saxony, Germany.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Klamerth
authors.affiliation: 7-285 Donadeo Innovation Centre for Engineering, Environmental Engineering Program, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada. mgamalel-din@ualberta.ca.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: 7-285 Donadeo Innovation Centre for Engineering, Environmental Engineering Program, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada. mgamalel-din@ualberta.ca and Department of Civil and Geological Engineering, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Kerry
authors.initials: K
authors.lastname: McPhedran
authors.affiliation: 7-285 Donadeo Innovation Centre for Engineering, Environmental Engineering Program, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada. mgamalel-din@ualberta.ca.
authors.forename: James R
authors.initials: JR
authors.lastname: Bolton
authors.affiliation: 7-285 Donadeo Innovation Centre for Engineering, Environmental Engineering Program, Department of Civil and Environmental Engineering, University of Alberta, Edmonton, Alberta T6G 1H9, Canada. mgamalel-din@ualberta.ca.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Gamal El-Din
mesh_terms: D004755:Enterobacteriaceae / Q000378:metabolism*; D008027:Light; D013472:Sunlight; D014466:Ultraviolet Rays; D062065:Wastewater / Q000382:microbiology*; D014876:Water Pollution / Q000517:prevention & control; D018508:Water Purification / Q000379:methods
chemical_list: D062065:Wastewater