Norman Invents Low-Cost, Low-Tech Arsenic Filter, March 1, 2001

SOCORRO, N.M., March 1, 2001 -- David Norman, a professor of geochemistry at New Mexico Tech, recently was awarded a $25,000 grant from the Conrad N. Hilton Foundation to further develop his new "low-tech" method of removing arsenic from drinking water.

The simple filtering device Norman has invented consists entirely of a five-gallon plastic bucket with a hole on the bottom, filled with crushed and screened laterite--a weathered reddish-brown material composed primarily of hardened clumps of iron oxide, which occurs naturally in some soils.

Through the Hilton Foundation grant, Norman will adapt his bucket-filter technology for use in villages in Ghana where villagers are often subjected to high arsenic levels in their drinking water, which is typically drawn from communal wells.

"In our field studies in Ghana, we came across water with so much arsenic that drinking it will result in skin problems and cancer," Norman relates. "But after we ran it through the bucket filter, you could safely drink the stuff. . . . These type of filters are awesomely efficient."

Once instructed on how to make bucket filters, Ghanaians would have little trouble constructing their own arsenic filtering devices, Norman maintains, since most of the required materials--discarded plastic buckets, window screens, and laterite-rich soil--are readily available throughout Ghana and other neighboring African countries.

Norman's research also has shown that buckets filled with ground up laterite can be used to filter out high concentrations of iron from drinking water.

"Basically, that's iron taking out iron," the Tech geochemist points out. "And, we really don't know why this is happening. . . . We just know that it works just as well."

Laterite deposits also occur in soils found in some of our own country's north-central states, including Michigan, Wisconsin, and Minnesota, Norman explains, and, as such, the bucket-filter technology might also have applications for residents of those states where high-iron content in their water poses problems with hard-water stains.

"It might eventually be possible to develop a smaller, cartridge-type filter filled with laterite as an active ingredient to effectively remove most of the iron out straight from the tap," Norman says.

With the grant from the Hilton Foundation, the bucket-filter technology, which is more technically described as a "continuous sorption column," also will be adapted to a larger-scale, square-meter-sized, concrete-encased filtering system which will be employed in larger Ghanaian villages for their communal wells.

World Vision, a nonprofit international organization which is committed to advocacy for children, has also pledged to assist Norman and his fellow researchers by providing them with trucks
to transport people and equipment in Ghana as they set up various water-filtering systems.