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17-Aug-2016 11:22

In research conducted in 55 households of Bonao, Dominican Republic, the average E. Lab tests have shown that while the filters reduce significant quantities of E.coli, they remove signifiicantly fewer viruses because viruses are smaller.Ideally, this should be high enough to keep the biofilm in the sand layer wet and allow oxygen to diffuse through the standing water to the biolayer.The pause period allows microorganisms in the biolayer to consume the pathogens and nutrients in the water.It is estimated that over 200,000 BSFs are in use worldwide. The Canadian non-profit company Center for Affordable Water and Sanitation Technology (CAWST) was co-founded in 2001 by David Manz and Camille Dow Baker to promote education and training in water purification and sanitation including using this technology, and to continue developing it.

Because of their effectiveness, ease of use, and lack of recurring costs, biosand filters are often considered appropriate technology in developing countries.

The "swirl and dump", or wet harrowing cleaning technique, is used to restore flow rate.

About 1 US gallon (3.8 l) is poured into the filter before cleaning (assuming the filter is empty).

Although slower flow rates generally improve water filtration due to idle time [APS1], it may become too slow for the users’ convenience.

If flow rates fall below 0.1 litre/minute, it is recommended by CAWST to perform maintenance.

The high water level (hydraulic head) in the inlet reservoir zone pushes the water through the diffuser and filter, then decreases as water flows evenly through the sand.



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