God knows we've written our share of water purification posts, but this is pretty cool: An Australian professor has come up with a way of making DIY water purifiers (PDF), suitable for the developing world:

A handful of clay, yesterday’s coffee grounds and some cow manure: the ingredients that could bring clean, safe drinking water to much of the third world. The simple new technology, developed by [Australia National University] materials scientist Mr. Tony Flynn, allows water filters to be made from commonly available materials and fired on the ground using cow manure as the source of heat, without the need for kiln. The filters have been tested and shown to remove common pathogens including E-coli.

They are very simple to explain and demonstrate and can be made by anyone, anywhere,” says Mr Flynn. “They don’t require any western technology. All you need is terracotta clay, a compliant cow and a match.”

Commercial ceramic filters do exist, Flynn says, but with prices which are often too expensive most people in the developing world. (The PDF also includes a step-by-step guide for making your own -- paging Mark Frauenfelder) Flynn has declined to patent his invention.

It works through microfiltration, as the creator explains in this interview:

BLANCH : So what are the basic principles that allow the filtration process to work so effectively?

FLYNN : Well, in the case of the addition of coffee grounds to the local clay, it does a couple of things. First of all it greatly increases the total volume of the tiny holes or pores within the filter structure and when it’s fired as I’ve just described in the manure mound, the heat burns the coffee out, leaving the holes but which also contain small fractions of silica that aren’t combustible and are a result of the combustion of the combustible fraction of the coffee grounds. Now these small voids or holes in conjunction with their silica content and the network of tiny holes that are joined in three dimensions within the clay particle mass, act as the filter structure and they are small enough to allow the simultaneous passage of water through them, while equally being small enough to remove bacteria that we tested for – in this case E-coli.

Being maybe the least craft-y person in the world, I'm not sure I'd want to trust my life to anything I made by hand, but still, if it holds up under scrutiny, this seems to me to be a great example of the kind of innovation, simple-yet-advanced, that so much of the world needs. It sort of goes well with "Pot-in-Pot" refrigerator designs, I think.

(treehugger)

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