UNESCO introduces low-cost water filter to remove arsenic

13 October 2005 –

With potentially poisonous arsenic in drinking water being both a natural phenomena and a toxic by-product of mining, mineral extraction and coal-burning electricity production, the United Nations Educational, Scientific and Cultural Organization (UNESCO) today unveiled a low-cost filter, made from an industrial waste product that is designed to remove the harmful substance.

Prevention is the only recourse since there is no medical treatment for intoxication by arsenic-contaminated water, the agency said in launching the innovation at its Paris headquarters.

"The technology we developed is based on arsenic absorption with iron oxide coated sand. If you produce the material commercially it is very expensive and when its absorption capacity is exhausted, you have to replace it and dispose of the waste," said Branislav Petrusevski, Director of the UNESCO-IHE Institute in Delft, The Netherlands, which offers post-graduate training and research programmes on water and the environment to developing country professionals.

Instead, the Institute team recycled iron oxide coated sand produced as a by-product in groundwater treatment plants. The filter is easy to use, requires no power and can be produced locally. The "family" filter produces 100 litres of arsenic-free water per day, enough to supply the needs of 20 people.

"Plants in many countries around the world use natural sand for iron removal and have to replace it after a certain number of years. We found that this material, now coated with iron oxides, is an excellent absorbent for removing arsenic from water. It is free of charge and consequently the technology based on its use is cheap," Mr. Petrusevski said.

He pointed out that the UN World Health Organization (WHO) has set the healthy maximum of arsenic in water at 0.01 milligrams per litre, but added that according to WHO estimates "arsenic levels in groundwater in Bangladesh, for example, are as high as 1.8 milligrams per litre."

Since February 2004, 14 "family filters" have been tested in rural Bangladesh where highly-contaminated groundwater has arsenic levels of up to 0.5 milligrams per litre. After more than 18 months of daily use, 12 of them were still producing arsenic-free water without needing replacement of the sand absorbent. Another 1,000 filters would be distributed in Bangladesh in the project's second phase.

Arsenic is a serious problem in many other countries, including Argentina, Chile, China, Ghana, Hungary, India, and Mexico and the United States.

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