LifeStraw
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The LifeStraw is an instant water purification filter designed by the Danish Vestergaard Frandsen Group.[1]. The device is able to clean bacteria, such as typhoid, salmonella, Escherichia coli, and cholera, from water for people living in third world countries[2].
[edit] Construction
The LifeStraw is a plastic tube 25 centimeters long and 29 millimeters in diameter[3], and costs around $2.00[4]. Water that is sucked through the straw first passes through a mesh of 100-micrometer spaces, then through a mesh of 15-micrometer spaces. Water then passes through a chamber with iodine-coated beads, killing remaining bacteria. The water passes through an empty chamber, then finally passes through active carbon, removing the iodide taste and medium-sized bacteria.[5] The entire process is powered by regular sucking, similar to using a conventional drinking straw, and filters up to 700 liters of water.[6]
[edit] Critical response
LifeStraw has generally been praised for its effective and instant method of bacteria removal. However, the device is ineffective at killing Giardia lamblia, an organism that is both resistant to iodine and smaller than 5 micrometers.[5] The device also causes higher-than-normal iodine levels in the drinkers' water, although this is countered by the iodine deficiency problem that exists in the third world. Paul Hetherington, of the charity WaterAid, has also criticised the LifeStraw for being too expensive and not solving the problem. He says that the price is expensive to those who would need it, and that it does not alleviate other problems in third world countries.[6]
