The BioSand Water Filter
Patented in 1993, the Davnor BioSand Water Filter is an innovative system that creates safe drinking
water for millions of people around the world using 170-year-old
technology. Slow sand filtration is a low-tech process that has only
recently been modified to meet the needs of consumers and developing
nations.
The basic device consists of a large container filled with sand and
gravel. As water passes through the various layers, foreign particles
and organisms are filtered out and the end product is relatively safe
drinking water.
Though
simple to use, slow sand filtration has not met widespread success; it requires a continuous source of water and, at best, will
only remove 60 percent of pathogens. Alberta inventor Dr. David Manz
kept this in mind when developing the BioSand water filter, a
commercially successful invention that has proved invaluable in third
world countries. Modifications to the classic filter system include a
diffuser, which is fitted over the opening of the basin to distribute
the water gently over the top layer of sand. This method reduces the
level of disturbance to the most important part of the filter, the
biolayer.
The biolayer is formed with the accumulation of organic material in the
first layer of sand. Oxygen and nutrients are delivered through a small
reserve of water that remains on top of the filter, a feature that
distinguishes the BioSand filter from similar devices. The
microorganisms that make up most of the biolayer consume bacteria,
increasing the effectiveness of the filter and eliminating 90 percent of
pathogens. The sand absorbs viruses, iron and other small particles.
The BioSand filter runs on a demand basis and requires no electricity or
chemicals, making it ideal for communities with few resources. The
technology is applied to both the commercial version, which Dr. Manzs
company Davnor sells, and the concrete version, which is manufactured
and installed in developing countries.
Click here for more information on the Centre for Affordable Water and
Sanitation Technology.
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