Development of Family Filter for Arsenic Removal

Within this project a simple and low-cost arsenic removal system has been developed and tested under field conditions in rural communities in Bangladesh. The technology is a simple and low-cost point-of-use arsenic removal system and therefore appropriate for families living in rural communities in developing countries.

Acute intoxication effects caused by exposure to high arsenic concentration in food or water have been known for centuries. Recent studies on long-term human exposure to arsenic have shown that even very low amounts of arsenic in drinking water are associated with skin pigmentation changes, skin thickening and adverse neurological effects. Moreover, it can cause various forms of cancer in the skin, liver, lung, kidney and bladder. The disease symptoms caused by chronic arsenic ingestion are collectively known as arsenicosis.

Arsenic in drinking water, usually in highly toxic inorganic form, is known as the silent and slow killer because its presence is not revealed by taste, odour or colouring of the water. It takes, as a rule, more than 10 years for clear symptoms of arsenicosis to appear, for which there is no effective medical therapy or treatment. The only prevention is to provide arsenic-free drinking water. In order to minimize arsenic-related health risks, different regulatory agencies have set guidelines and regulations for arsenic concentration in drinking water.

Arsenic contamination of groundwater can be found on all continents, however, developing countries are often less able to implement appropriate technologies to treat the water especially in rural areas. Arsenic concentration in ground water (above Bangladeshi standard) indicates that 50,000 out of 80,000 villages are affected which means between 25% and 60% of the total population of Bangladesh is at direct risk to arsenicosis.

After several years of intensive laboratory and field research, the highly effective Family Filter for arsenic removal was developed. The technology is under patent of UNESCO-IHE.

The UNESCO-IHE Family Filter is based on adsorption onto Iron Oxide Coated Sand (IOCS), a by-product of drinking water industry. The filter can remove arsenic highly efficiently, irrespective of its speciation and level of concentration. The unit is very simple, operates under gravity and does not require any chemicals. The Family Filter can produce approximately 100 liter of arsenic-free water per day, sufficient for the drinking and cooking needs of more than 20 persons.

UNESCO-IHE, together with its partners, successfully demonstrated the effectiveness and operational simplicity of the Family Filter during field trials conducted in rural Bangladesh. Twelve Family Filters have been successfully operating in five Bangladeshi villages since February 2004 and have been consistently producing arsenic-free water from groundwater that is highly contaminated with arsenic.

Prolonged operation of family filters in rural Bangladesh confirmed that the UNESCO-IHE Family Filter could, on average, provide a family in rural Bangladesh with arsenic-free water (for drinking and cooking) for approximately two years without adsorbent replacement.

In addition to arsenic removal, the Family Filter can remove iron highly effectively, even in cases where the iron levels in ground water are extremely high.

Project demonstrated that local production of the UNESCO-IHE family filter is possible and that overall costs are low, which makes the technology appropriate for use in the rural communities.

Through on-going field and laboratory research UNESCO-IHE is working on further improvement of the family filter that should increase its potential to remove other impurities (e.g. manganese) possibly present in ground water.

UNESCO-IHE is at present searching for donors that will support implementation of the second phase of the project, namely provision of several hundreds of arsenic removal family filters to families in selected villages of Bangladesh and longer-term monitoring of their performance.