title: Efficiency of a closed-coupled solar pasteurization system in treating roof harvested rainwater.
abstract: Many studies have concluded that roof harvested rainwater is susceptible to chemical and microbial contamination. The aim of the study was thus to conduct a preliminary investigation into the efficiency of a closed-coupled solar pasteurization system in reducing the microbiological load in harvested rainwater and to determine the change in chemical components after pasteurization. The temperature of the pasteurized tank water samples collected ranged from 55 to 57°C, 64 to 66°C, 72 to 74°C, 78 to 81°C and 90 to 91°C. Cations analyzed were within drinking water guidelines, with the exception of iron [195.59 μg/L (55°C)-170.1 μg/L (91°C)], aluminum [130.98 μg/L (78°C)], lead [12.81 μg/L (55°C)-13.2 μg/L (91°C)] and nickel [46.43 μg/L (55°C)-32.82 μg/L (78°C)], which were detected at levels above the respective guidelines in the pasteurized tank water samples. Indicator bacteria including, heterotrophic bacteria, Escherichia coli and total coliforms were reduced to below the detection limit at pasteurization temperatures of 72°C and above. However, with the use of molecular techniques Yersinia spp., Legionella spp. and Pseudomonas spp. were detected in tank water samples pasteurized at temperatures greater than 72°C. The viability of the bacteria detected in this study at the higher temperature ranges should thus be assessed before pasteurized harvested rainwater is used as a potable water source. In addition, it is recommended that the storage tank of the pasteurization system be constructed from an alternative material, other than stainless steel, in order for a closed-coupled pasteurization system to be implemented and produce large quantities of potable water from roof harvested rainwater.
authors.affiliation: Department of Microbiology, Faculty of Science, Stellenbosch University, Stellenbosch, South Africa.
authors.forename: P H
authors.initials: PH
authors.lastname: Dobrowsky
authors.affiliation: Department of Microbiology, Faculty of Science, Stellenbosch University, Stellenbosch, South Africa.
authors.forename: M
authors.initials: M
authors.lastname: Carstens
authors.affiliation: Crest, Po Box 7129, Stellenbosch 7599, South Africa.
authors.forename: J
authors.initials: J
authors.lastname: De Villiers
authors.affiliation: Department of Microbiology, Faculty of Science, Stellenbosch University, Stellenbosch, South Africa.
authors.forename: T E
authors.initials: TE
authors.lastname: Cloete
authors.affiliation: Department of Microbiology, Faculty of Science, Stellenbosch University, Stellenbosch, South Africa. Electronic address: wesaal@sun.ac.za.
authors.forename: W
authors.initials: W
authors.lastname: Khan
mesh_terms: D001419:Bacteria; D003247:Conservation of Natural Resources; D060766:Drinking Water / Q000382:microbiology; D011891:Rain; D013472:Sunlight; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*
chemical_list: D060766:Drinking Water
keywords: Chemical and microbial quality; Pathogens; Roof harvested rainwater; Solar pasteurization