Friday, May 20, 2005

The LifeStraw

like typhoid, dysentery, and cholera are among the world's leading killers; and yet, they can readily be destroyed by proper sanitation. They stem largely from a lack of safe drinking water. By equipping a straw with a set of cheap filters, however, the problem can be neutralized at an affordable and individual level. Instead of relying on a community supply of purified or boiled water, the LifeStraw allows any person of any age to dip down to a lake or irrigation ditch and drink without fear of deadly infectious disease. It also provides a supply of much-needed iodine. From the site:
What first meets the water when sucked up is a pre-filter of PE filter textile with a mesh opening of 100 micron, shortly followed by a second textile filter in polyester with a mesh opening of 15 micron. In this way all big articles are filtered out, even clusters of bacteria are removed. Then the water is led into a chamber of iodine impregnated beads, where bacteria, viruses and parasites are killed. The second chamber is a void space, where the iodine being washed off the beads can maintain their killing effect. The last chamber consists of granulated active carbon, which role is to take the main part of the bad smell of iodine, and to take the parasites that have not been taken by the pre-filter or killed by the iodine. The biggest parasites will be taken by the pre-filter, the weakest will be killed by the iodine, and the medium range parasites will be picked up by the active carbon. The main interest to everyone is the killing of bacteria, and here our laboratory reading tells us that we have a log. 7 to log 8 kill of most bacteria. This is better than tap water in many developed countries.
This is a beautiful, brilliant application of cheap and simple technology that has the potential to save lives. For the impoverished of the world, it doesn't get much better than that.


Blogger Andrew Hitchcock said...

Hey, that is really neat. I remember reading a few years back about a water purification device designed by Dean Kamen. His uses power to create clean water (at 10 gallons/hour, using 500 watts), but the water filtering and power generation system together cost over $4000. I haven't heard much about it since it was first announced. The cool thing about the straw is that it is cheap and convenient. I wonder how often the filters have to be replaced and how much it costs. I thought I read that in rural Chinese villages they were using passive solar to clean up water. By sending the water through special pipes installed on roofs, the water would be boiled and sterilized. That would be an easy way to get lots of clean water using very little energy (maybe a pump, but that can be done by hand).

5/21/2005 5:34 AM  

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