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http://enviro.org.au/waterFilter.asp



Australian scientist creates free water filter to solve world's drinking water problems
A handful of clay, yesterday’s coffee grounds and some cow manure are the simple ingredients that could bring clean drinking water to developing countries around the globe.
Australia
19 January 2005

An innovative new technology, developed by Australian National University (ANU) materials scientist Mr Tony Flynn, allows water filters to be made from commonly available materials and fired on the ground using using only manure, without the need for a kiln, furnace or Western technology. The filters have been shown to remove common pathogens including E-coli, but unlike other water filtering devices, they are simple and inexpensive to make.

The World Health Organization (WHO) estimates that 80% of all sickness in the world is attributable to unsafe water and sanitation, whilst annually children under five suffer 1.5 billion episodes of diarrhoea, approximately four million of which are fatal.

Historically, water filters have been imported into developing nations.
“These filters are a hollow ceramic vessel filled with charcoal. They are intended to filter out suspended silt and bacteria. However, at around $US5 each, they’re too expensive for individuals in many developing communities to consider purchasing,” said Mr Flynn.

The new filters are designed to be made from materials within easy reach. “They are very simple to explain and demonstrate and can be made by anyone, anywhere. They don’t require any Western technology. All you need is terracotta clay, some used coffee grounds or tea leaves, a compliant cow and a match,” said Mr Flynn.

“Everyone has a right to clean water, these filters have the potential to enable anyone in the world to drink water safely.”

The production of the filters is extremely simple. Take a handful of dry, crushed clay, mix it with a handful of organic material, such as used tea leaves, coffee grounds or rice hulls, add enough water to make a stiff biscuit-like mixture and form a cylindrical pot that has one end closed. Dry the pot in the sun, then put the filter on to a layer of lumps of dry manure,
with a little straw, shredded bark or dead leaves, cover with two more layers of manure, light the straw and then top up the burning manure as required. In less than an hour the filters are finished.

“A potter's kiln is an expensive item and can take up to eight or nine hours to achieve temperatures we can get in an hour. It also needs expensive or scarce, non-renewable fuels, such as gas or wood, to heat it and experience to run it. With no technology, and no insulation, none of these restrictions apply. The only pre-requisites for this 'zero-tech' filter are manure for fuel, local red/yellow clay and used coffee grounds or tea leaves and a little water.

“We are deliberately not patenting this technology in the hope that it will be used freely and widely around the world. This is a simple water filter that really does have the capacity to deliver safe drinking water where it is most needed in the third world.”

The filtration process is simple, but effective. The basic principle is that there are passages through the filter that are wide enough for water droplets to pass through, but too narrow for pathogens and the fine colloidal material that can make water muddy and unpleasant.

Organic materials which are combined with the clay burn away during the firing process, leaving cavities that help produce the structure in which pathogens will become trapped.

The invention was born out of a World Vision project involving the community of Manatuto, in East Timor. The charity wanted to help rehabilitate a small pottery community that had been devastated in the civil war that led to East Timor's independence, the intention being to assist the Manatuto potters to produce their own water filters and perhaps produce enough to generate income through sales.

Initial research found the local Manatuto clay to be too fine — a problem solved by the addition of organic material. But the solution found for the Manutuo potters was specific to that community, its materials and its wood-fired kiln, and we looked for a way that would allow the same filter to be produced from local materials anywhere without dependence on Western technology in the process.

Manure firing, with no requirement for a kiln, has made this 'zero-technology' approach available anywhere it is needed.

Tests with the E-coli bacterium have seen the filters remove 96.4 to 99.8 per cent of the pathogen — well within safe levels. Using only one filter, a litre of clean water can be produced in just two hours.

Source: Tony Flynn and The Australian National University



 

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