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Water Sand could provide a cheap, simple water purfier.

Published on March 11th, 2009 | by Tina Casey

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Revved-Up Sand Could Purify Water



Sand could provide a cheap, simple water purfier.First there was the Life Straw.  Then there was the Aquaduct Tricycle.  Now ordinary sand could provide an answer to one of the thorniest problems of the future: how to purify drinking water for the many millions of people who don’t have access to a clean, disease-free source — and no means to pay for conventional water treatment.

Cryptosporidium and Waterborne Disease

Cryptosporidium is a genus of microscopic, chlorine-resistant parasite.  It is one of the most common causes of waterborne disease, even in the U.S, where it is both a drinking problem and a recreational hazard.  When they make that announcement that everyone has to clear the kiddie pool, that’s cryptosporidium.

Cryptosporidiosis is the potentially life-threatening diarrheal disease caused by the parasite.

Enter Sand Man

Dr. James Amburgey is assistant professor of Civil and Environmental Engineering at the University of North Carolina – Charlotte.  Searching for a simple, low-tech, low cost way to treat water for crypto, he came upon a system that relies on sand, piping, and some common chemicals.  The result is a stepped-up treatment system that works 30 to 50 times faster than conventional sand filtration.

Iron (III) chloride, also called ferric chloride, is the secret weapon that Dr. Amburgey deployed to rev up the process.  Normally, the tiny crypto parasite slips easily between grains of sand.  Both are negatively charged, exacerbating the slipperiness.  By adding a ferric chloride pretreatment to the water, Amburgey neutralized the Cryptosporidium’s surface charge.

One important advantage of Amburgey’s process is simplicity.  Instead of having to adjust the pretreatment chemicals for each water source, so far his tests have shown that the same dose is effective on local creeks, rivers, and wastewater.  And, practically any local source of sand or crushed rock can be used.

Another interesting factoid:  the process relies partly on recycled chemicals.  Much of the ferric chloride in use today is recycled from the steel-making process.

Other new developments in water filtration, like carbon nanotubes, promise a high-tech fix.  For the low-tech world, Amburgey’s approach could be just what the doctor ordered.

Image: Tom T on flickr.

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About the Author

Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. You can also follow her on Twitter @TinaMCasey and Google+.



  • http://bpglass.net/ wholesale glass bottles

    I am going to let everyone i know, know about this!

  • http://bpglass.net/ wholesale glass bottles

    I am going to let everyone i know, know about this!

  • Dave

    Interesting. Does this rapid sand filter also remove or inactivate viruses, E coli, cholera, salmonella and other harmful pathogens? Professor Amburgey; how does this help “millions of people in developing countries” more advantageously than biological slow sand filters? Would these filters be small filters used by individual families, or large corporate projects costing billions of dollars to construct? Where are individual families going to get ferric chloride, and do they know how to handle toxic chemicals? How are these filters cleaned? Are they sustainable technology – in other words do they need petroleum derived energy, and produce no toxic byproducts? Why would an individual family need 30 to 50 times as much water as can be produced by a slow sand filter? What about the millions of people who carry water in buckets to pour into their filters – can they carry 30 to 50 times more water? Your project sounds technically very cool, but not practical for developing countries, and environmentally unsustainable as it depends on toxic chemicals which require large amounts of energy to produce and which must be added to the system. The biosand filter, developed by Dr. Manz, is already doing a fine job purifying water and empowering local cultures in developing countries without making them dependent on chemical companies and corporate greed. As we now are experiencing, corporate greed brings on catastrophic results. How is your product better for people in developing countries? I challenge you to answer.

  • Dave

    Interesting. Does this rapid sand filter also remove or inactivate viruses, E coli, cholera, salmonella and other harmful pathogens? Professor Amburgey; how does this help “millions of people in developing countries” more advantageously than biological slow sand filters? Would these filters be small filters used by individual families, or large corporate projects costing billions of dollars to construct? Where are individual families going to get ferric chloride, and do they know how to handle toxic chemicals? How are these filters cleaned? Are they sustainable technology – in other words do they need petroleum derived energy, and produce no toxic byproducts? Why would an individual family need 30 to 50 times as much water as can be produced by a slow sand filter? What about the millions of people who carry water in buckets to pour into their filters – can they carry 30 to 50 times more water? Your project sounds technically very cool, but not practical for developing countries, and environmentally unsustainable as it depends on toxic chemicals which require large amounts of energy to produce and which must be added to the system. The biosand filter, developed by Dr. Manz, is already doing a fine job purifying water and empowering local cultures in developing countries without making them dependent on chemical companies and corporate greed. As we now are experiencing, corporate greed brings on catastrophic results. How is your product better for people in developing countries? I challenge you to answer.

  • http://www.bottlesandmore.com Glass Bottles

    Hmm…interesting article. Dr. Amburgey has got a novel idea there. I just hope the good Dr. can guarantee pure water and help less fortunate people out.

  • http://www.bottlesandmore.com Glass Bottles

    Hmm…interesting article. Dr. Amburgey has got a novel idea there. I just hope the good Dr. can guarantee pure water and help less fortunate people out.

  • Ben N

    Time to get to work. Spread the word!

  • Ben N

    Time to get to work. Spread the word!

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