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'''Solar water disinfection''', also known as '''solar water pasteurisation''' or '''SODIS''', is a method of [[ | '''Solar water disinfection''', also known as '''solar water pasteurisation''' or '''SODIS''', is a method of [[Water disinfection|disinfecting]] [[Drinking water]] using the heat and (usually) the [[UV]] light of the sun. It is a very simple and [[Low cost]] way of disinfecting small volumes of water. | ||
Radiation in the spectrum of UV-A (wavelength 320-400nm) and increased water temperature. Both factors cause damage to the DNA of the [[ | Radiation in the spectrum of UV-A (wavelength 320-400nm) and increased water temperature. Both factors cause damage to the DNA of the [[Pathogens]]. The effects are also synergistic - the DNA being more prone to UV damage if the temperature is very high. If the water temperatures raises above 50°C, the disinfection process is three times faster, and much better results are obtained from | ||
Certain pathogens such as [[ | Certain pathogens such as [[Giardia]],{{wp sup|giardia}} however, are not easily killed by UV. For these, the heat is more important,{{fact}}. | ||
==Usability== | == Usability == | ||
*Keep in mind that SODIS is only intented as a disinfection method. When the water is highly turbid, additional steps (filtering) is necessairy.<ref>[http://www.cepis.org.pe/cursodesastres/diplomado/pdf/SODIS.pdf Limitations of SODIS]</ref> | |||
== SODIS - solar water disinfecting with soda bottles and sunlight == | |||
Solar water disinfection, or [[SODIS]]{{wp sup|SODIS}}, is a method to disinfect water using sunlight and PET bottles. | |||
<br> | |||
*Water from contaminated sources are filled into transparent water bottles. For oxygen saturation, bottles can be filled three quarters, then shaken for 20 seconds (with the cap on), then filled completely. Highly turbid water (turbidity higher than 30 [[Nephelometric Turbidity Unit|NTU]]) must be filtered prior to exposure to the sunlight. | |||
*Filled bottles are then exposed to the sun. Better temperature effects can be achieved if bottles are placed on a corrugated roof as compared to thatched roofs. | |||
*The treated water can be consumed. The risk of re-contamination can be minimized if water is stored in the bottles. The water should be consumed directly from the bottle or poured into clean drinking cups. Re-filling and storage in other containers increases the risk of contamination. <br> | |||
Effectiveness can be increased by placing on a dark or reflective surface, e.g. | |||
*a roof made of corrugated metal. | |||
*or by painting half the bottle black, such that when laying down the clear half is facing the sky. | |||
== | == Using reflectors == | ||
[http://aem.asm.org/cgi/content/full/65/2/859 Enhancement of Solar Water Pasteurization with Reflectors], Negar Safapourdagger and Robert H. Metcalf, 1998, Department of Biological Sciences, California State University Sacramento, Sacramento, California. | |||
This uses simple cardboard based reflectors and a black jug. Heat is considered by the authors to be the more reliable mechanism for disinfection. | |||
See also: [[CPC]]s | |||
=== | == History == | ||
Prof Aftim Acra of Lebanon researched this technique beginning in 1979. See [http://www.bourgoing.com/presse/libancrdienglish.htm Cleaning water with sunshine], Robert Bourgoing, ''IDRC Reports, April 1989.'' (or http://www.appropedia.org/Special:Userlogin%26type%3Dsignup get one now [http://idrinfo.idrc.ca/archive/ReportsINTRA/pdfs/v18n2e/108893.pdf the original format with image, in PDF].) See also [http://wwwlb.aub.edu.lb/~webmgate/winter04/reflections.html An Interview with Aftim Acra, Professor Emeritus of Environmental Sciences], Winter 2004. | |||
[[Category:Howtolive]] | == Interwiki links == | ||
[[Category:Solar]] | |||
[[Category: | *[[wikipedia:Solar water disinfection|RTENOTITLE]] | ||
== External links == | |||
*[http://www.sodis.ch/Text2002/T-Research.htm Scientific Publications on Solar Water Disinfection] at the SODIS website. Links to PDF format articles. | |||
*[http://imageevent.com/bobmetcalf/watertestingpasteurizationinafrica;jsessionid=ziw8fco341.tiger_s?n=0&z=2&c=4&x=1&m=24&w=0&p=0 Water testing & Pasteurization in Africa] - A guide to water testing without access to a laboratory, and how to pasteurize contaminated water using sunshine and a simple solar cooker. Images with captions, by Bob Metcalf. | |||
=== Project links === | |||
*The [http://www.sodis.ch/Text2002/T-Contacts.htm Contacts] page on the SODIS website has many case examples in PDF form. | |||
*Bintaro Baru in South Jakarta: Yayasan Emmanuel Water Program[http://www.yewaterprogram.org/] - SODIS program described at [http://www.adb.org/Water/Actions/INO/solar-disinfection.asp#a2 Country Water Action: Indonesia Simple Science Solves Slum Water Problem] ([[Asian Development Bank]] site, from Asiawaterwire.net, August 2007) | |||
{{Stub}} | |||
[[Category:Howtolive]] [[Category:Solar]] [[Category:Water_purification]] |
Revision as of 22:58, 30 August 2010
Solar water disinfection, also known as solar water pasteurisation or SODIS, is a method of disinfecting Drinking water using the heat and (usually) the UV light of the sun. It is a very simple and Low cost way of disinfecting small volumes of water.
Radiation in the spectrum of UV-A (wavelength 320-400nm) and increased water temperature. Both factors cause damage to the DNA of the Pathogens. The effects are also synergistic - the DNA being more prone to UV damage if the temperature is very high. If the water temperatures raises above 50°C, the disinfection process is three times faster, and much better results are obtained from
Certain pathogens such as Giardia,W however, are not easily killed by UV. For these, the heat is more important,[verification needed].
Usability
- Keep in mind that SODIS is only intented as a disinfection method. When the water is highly turbid, additional steps (filtering) is necessairy.[1]
SODIS - solar water disinfecting with soda bottles and sunlight
Solar water disinfection, or SODISW, is a method to disinfect water using sunlight and PET bottles.
- Water from contaminated sources are filled into transparent water bottles. For oxygen saturation, bottles can be filled three quarters, then shaken for 20 seconds (with the cap on), then filled completely. Highly turbid water (turbidity higher than 30 NTU) must be filtered prior to exposure to the sunlight.
- Filled bottles are then exposed to the sun. Better temperature effects can be achieved if bottles are placed on a corrugated roof as compared to thatched roofs.
- The treated water can be consumed. The risk of re-contamination can be minimized if water is stored in the bottles. The water should be consumed directly from the bottle or poured into clean drinking cups. Re-filling and storage in other containers increases the risk of contamination.
Effectiveness can be increased by placing on a dark or reflective surface, e.g.
- a roof made of corrugated metal.
- or by painting half the bottle black, such that when laying down the clear half is facing the sky.
Using reflectors
Enhancement of Solar Water Pasteurization with Reflectors, Negar Safapourdagger and Robert H. Metcalf, 1998, Department of Biological Sciences, California State University Sacramento, Sacramento, California.
This uses simple cardboard based reflectors and a black jug. Heat is considered by the authors to be the more reliable mechanism for disinfection.
See also: CPCs
History
Prof Aftim Acra of Lebanon researched this technique beginning in 1979. See Cleaning water with sunshine, Robert Bourgoing, IDRC Reports, April 1989. (or http://www.appropedia.org/Special:Userlogin%26type%3Dsignup get one now the original format with image, in PDF.) See also An Interview with Aftim Acra, Professor Emeritus of Environmental Sciences, Winter 2004.
Interwiki links
External links
- Scientific Publications on Solar Water Disinfection at the SODIS website. Links to PDF format articles.
- Water testing & Pasteurization in Africa - A guide to water testing without access to a laboratory, and how to pasteurize contaminated water using sunshine and a simple solar cooker. Images with captions, by Bob Metcalf.
Project links
- The Contacts page on the SODIS website has many case examples in PDF form.
- Bintaro Baru in South Jakarta: Yayasan Emmanuel Water Program[1] - SODIS program described at Country Water Action: Indonesia Simple Science Solves Slum Water Problem (Asian Development Bank site, from Asiawaterwire.net, August 2007)