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[[Image:Sodis.PNG|thumb|right|150px|Plastic bottles filled with contaminated water are placed in the sunlight ]]
The idea of fact that sunlight can kill micro-organisms has been known for centuries and has been scientifically established. Solar disinfection is a simple water treatment method using solar water disinfection radiation (SODISUV-A light and temperature) was presented by Professor Aftim Acra for to destroy pathogenic bacteria and viruses present in the first time in a booklet published by UNICEF in 1984water. It can be used to disinfect small quantities of water with low turbidity. SODIS has been promoted worldwide since 1991 when an interdisciplinary research team at EAWAG/SANDEC began laboratory Most commonly, contaminated water is filled into transparent plastic bottles and field tests exposed to assess full sunlight. The pathogens are destroyed during the potential of SODIS and exposure to develop an effective, sustainable and low cost water treatment methodthe sun. Solar disinfection is recommended by Users determine the length of exposure based on the World Health Oganization (WHO) as one viable option for drinking water treatment at household levelweather conditions.
Other forms of batch treating and continuous treatment of water with sunlight are under development by various organizations.
{{procontable | pro=
- Very cheap, no capital costs except plastic bottle, no consumables required. <br>
- Independent from energy sources other than sunlight. <br>
- Treated water is protected from re-contamination in the bottles.<br>
- The taste of treated water is fresh, not stale or otherwise altered.<br>
- Convenient for storage and transportation.
- SODIS has shown to significantly reduce diarrhoea
| con=
- Cannot be used on days with continuous rainfall.<br>
- Cannot be used to treat very turbid water (>30 NTU).<br>
- Bottles need to be replaced every 4-6 months.<br>
- Has a waiting period of 6-12 hours. <br>
- Needs to be cooled before consumption <br>
- Does not remove suspended partices of dissolved compounds<br>
}}
==History and social context==
The idea of solar water disinfection (SODIS) was presented by Professor Aftim Acra for the first time in a booklet published by UNICEF in 1984. SODIS has been promoted worldwide since 1991 when an interdisciplinary research team at EAWAG/SANDEC began laboratory and field tests to assess the potential of SODIS and to develop an effective, sustainable and low cost water treatment method. Solar disinfection is recommended by the World Health Oganization (WHO) as one viable option for drinking water treatment at household level.
==Suitable conditions ==
* Do not use SODIS during days of continuous rainfall, use rainwater harvesting instead.
The efficiency of SODIS is dependent on the amount of sunlight available. The bottles must NOT be placed so that they are in shade for part of the day. The most favourable geographical regions for SODIS are located between latitudes 15oN and 35oN (as well as 15oS and 35oS). The majority of developing countries are located between latitudes 35oN and 35oS (EAWAG/SANDEC, 2002). If the water bottles are not exposed to sunlight for the proper length of time, the water may not be safe to drink and could cause illness. If the day is more than 50% cloudy, then it is necessary to expose the bottles for 2 days. If the temperature of the water is more than 50 degrees C, only 1 hour of exposure is required.
After treatment, the 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 recontamination. Non-pathogenic organisms, such as algae, may grow in the conditions created in a SODIS bottle (EAWAG/SANDEC, 2002).
