Posted by Patty Osborne

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    The clay thing is a great idea at first glance. However, there are a couple problems:
    First, the rarity of the substance. Second, the cost of transporting rock to where ever.
    Third and last: this system of disinfection goes head-to-head with at “working” system which uses a silver colloid which is relatively easy to make (and not really rare) and certainly weighs considerably less than bags of clay.

    There is one possibility which might make the clay approach viable: persistence of the effect in the final form in which it will be used. If it can be show to be significantly longer-working than the silver, that might tip the scales in its favor.

    However, I have to wonder at the wisdom of someone having spent nearly 400,000 dollars on this project (assuming the disclosed grant amount is accurate), only to find some rare substance of indeterminate effectiveness.

  2. Has your organization considered the use of anti-bacterial clays in the pots? That would avoid the need for using silver based coating.

    Recent studies at ASU (Tempe) by Prof. Williams confirm that certain clays are naturally anti-bacterial. The studies were sponsored by the National Science Foundation.

    See recent NSF announcement:

    I can provide samples of this clay.

    Ray Kapahi
    Sacramento, CA
    Tel: 916-687-8352

    • Hi Ray,
      Thank you for your message. This is certainly a very interesting topic. Previously in a 2009 study by Joe Brown, several electropositive iron oxides (goethite, magnetite, hematite) and alumina oxides were added to clay and tested for anti-microbial and anti-viral effects in the context of drinking water. It is my understanding that beneficial effects were measured, however as Raymond Barnum mentioned in his comment below, the difficulty is in the cost of transporting these clays long distances in sufficient quantities. However if iron-rich clays are available near a production site, they could certainly be tested and used in filter production. It would be great to explore this idea in more detail and I will be sure to pass this study on to folks studying clay characteristics. Thanks again for sharing this information!
      All the best,

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