About Water Purification
According to the World Health Organization, over 1 billion people lack access to safe drinking water, with 1.8 million dying as a result of infections contracted from drinking dirty water. This is mostly confined to the developing world, but even in industrialized countries, water purification is a major issue due to the vast amount of sewage created in our cities, industrial pollution and crumbling or defective infrastructure. Everyone is either heavily reliant on or desperately in need of water purification technology to live.
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Chemical Treatment
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Chemicals are often added to water to kill microorganisms. Iodine is familiar to most serious trekkers or military personnel as a means of treating water far from support. Chlorine is a common additive in both the developed and developing world, with many people in poorer countries adding a few drops of bleach right into large jars or jugs of water. Both means need half an hour to thoroughly kill unwanted germs and parasites. A new chemical, combining chlorine dioxide and silver ions, is coming into general use, and it is more effective at killing giardia and cryptosporidium than either iodine or chlorine. Chemical treatment needs to be combined with filtration to fully purify water.
Ultraviolet Treatment
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A popular treatment is to bombard water with heavy ultraviolet (UV) rays. UV rays destroy DNA and, while that might not kill microorganisms, it will stop them from reproducing. That dramatically curtails the impact of any infection, usually to the point of being negligible. UV treatment needs to be combined with filtration to fully purify water.
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Boiling
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It's old-fashioned, but effective. Boiling water for several minutes (or a few dozen at higher altitudes) kills microorganisms. When combined with filtration, the technique is quite effective.
Solar Disinfection
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This is another technique useful to campers, soldiers and people living in the developing world. Simply take some water, put it in a clear plastic (not glass) container, and leave it out in the sun on a hot day for several hours. The steady, natural UV rays will take care of most microorganisms, making this an effective means of cleaning up suspect water. This treatment needs to be combined with filtration to fully purify water.
Filtration
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The oldest filtration system is still in use, even in household filters like those made by Pur or Brita. They use the properties of charcoal to draw impurities out of the water. Other filter methods include ceramic filters (which mimic the effects of soil and stone as filters on groundwater), and reverse osmosis filters. These are at their best when removing solids and chemicals from water supplies, but reverse osmosis in particular is also effective against microorganisms. Therefore, some filtration systems might need to be combined with treatment by chemicals, UV rays, or boiling.
Distillation
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Solar stills are often used in water purification. This technique uses the heat of the sun and either glass or clear plastic to evaporate water, leaving impurities and infectious creatures behind. The distillation technique can be applied through use of an actual still, purifying much larger amounts of water at greater speed, but at greater cost.
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Resources
- Photo Credit Wikimedia Commons
