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[[Image:CAWST_Kachan.png|thumb|right|250px300px| Cross-section through a Kachan Arsenic Filter]]
The Kanchan Arsenic Filter (KAF) is an adaptation of the biosand filter (BSF). It is based on slow sand filtration and iron hydroxide adsorption principles. The KAF has been designed to remove arsenic from drinking water, in addition to providing microbiological water treatment. Arsenic removal is achieved by incorporating a layer of non-galvanized nails in the diffuser basin of the filter.
This filter was developed by researchers at Massachusetts Institute of Technology (MIT), Environment and Public Health Organization (ENPHO) of Nepal, and Rural Water Supply and Sanitation Support Programme (RWSSSP) of Nepal.
===Suitable conditions===
It is suitable to process batches of 12-18 litres. If two batches a day are filtered, this provides 24-36 litres of clean water.
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===Construction, operations and maintenance===
The filter container can be constructed out of concrete or plastic. The container is about 0.9 m tall and either 0.3 m square or 0.3 m in diameter.
Free mold designs are available from CAWST.
===Costs===
{{Treatment_Cost
|CapCost=US$ 12-30
Note: Program, transportation and education costs are not included.
===Field experiences===
==Reference manuals, videos, and links==
*[http://www.cawst.org CAWST (Centre for Affordable Water and Sanitation Technology)]
*[http://www.enpho.org/drinking_water_quality.htm Drinking water quality information from Environment and Public Health Organization (ENPHO)]
*[http://web.mit.edu/watsan/tech_hwts_chemical_kanchanarsenicfilter.html Kanchan Arsenic filter information from Massachusetts Institute of Technology (MIT)]
==Footnotes=References===
<references/>
===Acknowledgements===
This article is based on a factsheet from [http://www.cawst.org/ Centre for Affordable Water and Sanitation Technology (CAWST)], which is gratefully acknowledged.
