Four years of development and field-testing of IHE arsenic removal family filter in rural Bangladesh.

UNESCO-IHE has been developing an arsenic removal family filter with a capacity of 100 L/day based on arsenic adsorption onto iron oxide coated sand, a by-product of iron removal plants. The longer term and field conditions performance of the third generation of eleven family filters prototypes were tested in rural Bangladesh for 30 months. All filters achieved initially highly effective arsenic removal irrespective of arsenic concentration and groundwater composition. Arsenic level in filtrate reached 10 μg/l after 50 days of operation at one testing site and after 18 months of continuous operation at other 3 testing sites. Arsenic level at other 7 sites remained below the WHO guideline value till the end of study. Positive correlation was found between arsenic removal capacity of the filter and iron concentration in groundwater. In addition to arsenic, iron present in groundwater at all testing sites was also removed highly effectively. Manganese removal with IHE family filter was effective only when treating groundwater with low ammonia. A simple polishing sand filter, after IHE family filter, resulted in consistent and effective removal of manganese. IHE family filters were easy to operate and were well accepted by the local population.