Decontamination of drinking water by direct heating in solar panels |
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| Authors: | AJ Fjendbo Jørgensen K Nøhr H Sørensen & F Boisen |
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| Institution: | Odense University Hospital,;Department of Gender Studies, Odense University,;Odense Technical College,;Microbiology Department, Environmental and Food Agency, Odense, Denmark |
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| Abstract: | A device was developed for direct heating of water by solar radiation in a flow-through system of copper pipes. An adjustable thermostat valve prevents water below the chosen temperature from being withdrawn. The results show that it is possible to eliminate coliform and thermotolerant coliform bacteria from naturally contaminated river water by heating to temperatures of 65 °C or above. Artificial additions of Salmonella typhimurium , Streptococcus faecalis and Escherichia coli to contaminated river water were also inactivated after heating to 65 °C and above. The total viable count could be reduced by a factor of 1000. The heat-resistant bacteria isolated from the Mlalakuva River (Tanzania) were spore-forming bacteria which exhibited greater heat resistance than commonly used test bacteria originating from countries with colder climates. To provide a good safety margin it is recommended that an outlet water temperature of 75 °C be used. At that temperature the daily production was about 50 l of decontaminated water per m2 of solar panel, an amount that could be doubled by using a heat exchanger to recycle the heat. |
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