LifeStraw™ is a simple device, still in a prototype phase, designed for those unfortunate people in the third world who do not have access to clean drinking water. The pipe is composed of two textile filters, followed by a chamber with beads impregnated with iodine:
Functionallity and use of design:
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.
Drawbacks of life improvement:
If we were not able to control the output of iodine there could have been a draw back there, but with the existing iodine deficiency in most 3rd world communities, WHO would have appreciated if we had had a higher release of iodine. We have, however, chosen to put in so much granulated active carbon, that no consumer shall discard the filter due to chemical taste.
For those of you considering using LifeStraw™ for outdoor adventures in the continental United States, beware that the common "beaver fever" (Giardia lamblia infection) is caused by an organism with 5 micron spores, which are resistant to iodine. http://www.index2005.dk/Members/dafude/bodyObject