Low-tech Solar Water Purification: It works
TANZANIA - A village is piloting a new way to purify water with simple means. The method is so simple it hurts to think that it has not been put into wide use. Take a transparent plastic water bottle, fill it up with water, lay it on a black roof for several hours. If the sun is beating down good, one hour is enough.
The combination of the sun's ultra violet rays and heat kills any pathogenic germs - the ones that spread much illness in Africa.
The beautiiful simplicity of the solution brings to mind another invention that received the Rolex prize a year ago: a no-electricity refrigerator made of two ceramic pots one inside the other. See this post on boing-boing for a link. There is also a neatly simple ceramic water filter technique linked from the same article.
Compare this with Dean Kamen's latest proposal for a machine that does a very similar job and that will cost between 1000 and 2000 $ when mass produced...
Here is the recent BBC article on solar water sterilization:
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Using the sun to sterilize water
Tanzanian villagers have begun using an energy-saving method to sterilize their drinking water - leaving the water under the sun.
The piped water supply to Ndolela village in the central Iringa region is intermittent and even when it does flow, it is not clean enough to drink.
When the pipes run dry, villagers get water from a dirty spring.
Mother of five Rose Longwa says the new process has changed her life.
"We no longer suffer from stomach illness. That's because the water is clean and safe."
Like many other people in rural Africa with no access to safe drinking water, she used to sterilise her water by boiling it.
But she says the smoke from the firewood to heat the water used to irritate her eyes. She is also glad she no longer has to go to fetch wood from the bush.
About 40 houses in Ndolela are using solar purification.
Mrs Longwa says the process is simple to follow.
"I fill the plastic bottles, put the lids on, then put them on my black-painted roof where they stay for a whole day."
The sun heats the water, helped by the black roof, which helps to absorb the heat.
Solar radiation means a combination of ultra-violet rays and heat destroys the bacteria which cause common water-borne diseases like cholera, typhoid, dysentery and diahorrea.
After eight hours in the sun, it is ready to drink.
If the water reaches more than 50C, it is safe in just one hour.
Pastor Moses Kwanga from the Diocese of Ruaha is behind the project:
"The technology is very easy, but up to now people have not been told about it. We can use old pieces of roofing to put the bottles on. It is also very cheap, so is accessible to everyone."
Up to now, the number of people in Tanzania purifying water using the power of the sun is limited to a few villages like Ndolela, where small-scale education programmes are underway.
Daudi Makamba is a water expert for the aid agency Plan International, which is considering whether to introduce solar purification across the country.
He says it can be difficult to persuade people to use the technology.
"The big resistance from the community is cultural beliefs. People believe the water will be contaminated, or an enemy will put something bad in it, so we need to educate the people."
The technology is working well for at least one community in Tanzania but more work is needed if more people are to taste the benefits.
OpenWater is an educational video about where to find water in a disaster and different methods of purifying water. The five minute video uses a combination of pictures, video footage and music to convey the importance of clean water and that purifying water isn't a complicated process. If you have one, we encourage you to put OpenWater on your portable media player in case of an emergency. If you don't have a portable media player, print out the Water Purification page and store it with your 72-hour kit.
Ma's invention features 66 beer bottles attached to a board. The bottles are connected to each other so that water flows through them. Sunlight heats the water as is passes slowly through the bottles before flowing into the bathroom as hot water, reports China Economy Network. Ma says it provides enough hot water for all three members of his family to have a shower every day.
Here is a video that explains the concept of solar water purification quite well:
posted by Sepp Hasslberger on Friday March 24 2006
updated on Saturday July 9 2011
URL of this article:
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