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Headlines Published on 06 February 2006

Title ‘Family filter’ stops arsenic in its tracks

Arsenic-laced groundwater is a silent but deadly problem affecting the world’s poorest nations – and a few richer ones as well. European researchers and their international partners have developed a new way to purify drinking water, dubbed the ‘family filter’ because of its ease of use and affordability for even the poorest families.

Installation of a trial family filter in Bangladesh. © UNESCO-IHE
Installation of a trial family filter in Bangladesh.
Arsenic is a slow, undetectable killer found in large tracts of the world’s groundwater, but especially in parts of Asia. In Bangladesh alone, up to 44% of the population is exposed to arsenic-laced drinking water, the World Health Organisation (WHO) estimates. The problem crosses into neighbouring countries, India (West Bengal) and Nepal, affecting tens of millions who have to drink untreated groundwater.

It can take years of exposure to arsenic before clear symptoms may appear, such as pigmentation changes, ‘hyperkeratosis’ (patches of thickening skin), neurological side effects and signs of possible cancers in major organs (skin, liver, lungs, kidneys and bladder). By this time, the chronic disease arsenicosis has set in. Prevention is the only way to stop it, the experts lament.

Thankfully, European researchers and their international partners at UNESCO’s Institute for Water Education (IHE) in Holland have perfected a simple, efficient and – importantly – low-cost water filtration device which removes arsenic from contaminated drinking water. The filter uses iron oxide-coated sand which absorbs the arsenic from water at the “point of use” (i.e. well, tap).

“From the very beginning, it was clear to us that a ‘point of use’ system was the only feasible approach in the short term for rural areas of developing countries with no piped water supply,” writes UNESCO scientist Branislav Petrusevski in the latest issue of A World of Science. Because only 2-3% of water is used for cooking and drinking, the researchers decided to limit the filtration scheme and to keep it simple enough for rural families to install and use. Thus, after five-years under development, the ‘family filter’ was born.  

Potential users of the new filter are not only in the world’s poorest nations. Families on farms or not connected to town water in countries, such as Australia, New Zealand and Argentina, or (closer to home) in parts of Hungary and Serbia – which all have documented arsenic levels above WHO safety margins of 10 μg/l – could potentially benefit from the new technology.

Trial but no error
The filter’s environmental credentials are also sound, according to the report. The iron oxide-coated sand is a by-product of large-scale water treatment – initially, it will have to be imported into the countries with no equivalent treatment plants in built-up areas – it needs no added chemicals, and the filter uses gravity (hence no power needed). What’s more, UNESCO-IHE tests indicate the resulting arsenic-covered sand will percolate (leach naturally) back into the environment, which means it is safe to use as landfill or in construction.

Initial trials of the filter in Bangladesh not only prove its effectiveness in removing arsenic but also that the absorbent was still working well after 12 months in use. Extrapolating these results, the scientists reckon the treated sand could last up to two years without replacement. A second phase of trials will begin this year, where up to 1 000 families in Bangladesh will receive filters to test out.   

In addition to its own research activities, UNESCO-IHE is active in education, training and capacity building in organisations, knowledge centres and other institutions active in the fields of water, the environment and infrastructure, with emphasis on developing countries and countries in transition. For this reason, it has consciously decided not to patent the family filter.

“It is our hope that the absence of a patent will enable the technology to spread unfettered throughout the developing world,” concludes Petrusevski.

Source:  A World of Science, Vol. 4, No.1

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More information:

  • Water Policy in the EU (Environment DG)
  • European Environment Agency (Eurowaternet report)

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