Monday, May 16, 2005

Throw Away Your Brita

An Australian inventor claims that clay, dirt, coffee grounds and cow patties are all you need to make safe drinking water available to the entire world. He has developed a way to create terracota clay filters using all readily available materials, according to an interview with Radio Australia.

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

The filter is made by mixing terracotta clay, dirt and organic material (coffee grounds, tea leaves, rice hulls, etc). It then needs to be fired - but there is no kiln required. Flynn has developed a method to use cow dung and straw as a makeshift kiln.

The question that immediately came to my mind was - how does this creation actually filter water? Well Flynn has an answer for that one too.

"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."

Flynn hopes to test the process using clay and soil from other areas, and ultimately introduce the process to communities in the developing world that have little access to clean water or resources to produce it.

Via Treehugger.

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