[[Image:Ceramic_filter_icon.png|right|80px]][[Image:arsenic removal.jpg|thumb|right|250px200px| Arsenic removal system: oxidation method. <br>Photo: Ngai.]][[Image:arsenic removal two.jpg|thumb|right|250px200px|Magc-Alcan Filter (left) and Nirmal Filter (right): adsorption method. Photo: Ngai.]]__NOTOC__ <small-title />
There are at least five ways to remove arsenic from drinking water. The adsorption method, the coagulation-flocculation method, the surface complexation method, a Kanchan arsenic filter, or removal by oxidation.
Instead of adding chemical oxidants such as chlorine or permanganate, reactive oxidants are produced photo chemically with sunlight.
===Construction, operations and maintenance===
[[Image:shapla filter.jpg|thumb|right|200|Shapla arsenic filter. Photo: Ngai.]]
[[Image:2-Kolshi filter.jpg|thumb|right|200|2-Kolshi arsenic filter. Photo: Ngai.]]
Contaminated water is poured into the top of the filter on an intermittent basis. The water slowly passes through the diffuser, and percolates down through the biolayer, sand and gravel. Treated water naturally flows from the outlet. The biolayer is the key pathogen removing component of the filter. Without it, the filter is significantly less effective. It may take up to 30 days to establish the biolayer depending on inlet water quality and frequency of use. The water from the filter can be used during the first few weeks while the biolayer is being established, but disinfection is recommended during this time, as during regular on-going use.
Much more information and details on the Kanchan arsenic filter: [http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CFYQFjAB&url=http%3A%2F%2Fwww.cawst.org%2Fassets%2FFile%2FHWTS_Fact_Sheet_KAF/assets/File/HWTS_Fact_Sheet_KAF.pdf&ei=gz72T6esPOmy2QXl8-ToBg&usg=AFQjCNHExV2LsQy4IgoZzMR2avHnREOnsg&sig2=ClJFwW7vj9UkNrgU-4udPA Household Water Treatment and Safe Storage Factsheet: Kanchan Arsenic Filter.]
'''Oxidation: Passive'''<br>
* The water can then be filtered through textile cloth or clay filters
===Costs===
'''Adsorption: Magc-Alcan filter'''<br>
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===Field experiences===
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|[[Image:rsr 476.jpg|thumb|none|200px|<font size="2"><center>Project 476</center></font>|link=http://www.akvo.org/rsr/project/476/]]
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===Acknowledgements===* [http://www.googlesswm.cominfo/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&ved=0CHMQFjAC&url=http%3A%2F%2Fwww.cawst.org%2Ffr%2Fresources%2Fpubs%2Fcategory%2F25category/implementation-facttools/water-sheetspurification/hardware/point-academic%3Fdownload%3D40%253Ahwtsuse-factwater-sheetarsenictreatment/arsenic-removalpdfoct09&ei=oi32T5bROeWW2AWlremoval-fDCBg&usg=AFQjCNHtsMduzuzEZMNKHgbl2BN1dHjr2g&sig2=VgGZabK2qsBHhJQkLL2TKQ Household Water Treatment for Arsenic Removal Fact Sheet: Adsorption.] CAWSTRaju Shrestha, Environment and Public Health Organisation, ENPHO.* [http://wwwresources.googlecawst.comorg/asset/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CG4QFjAA&url=http%3A%2F%2Fafghanlivelihoods.com%2Fvirtualarsenic-removal-library%2FShelter%2Fbiosandfact-filtration%2Fresources%2Fcasesheets-studies%2Fcaseadsorption_fr French Factsheet]. CAWST.* [http://resources.cawst.org/asset/arsenic-studyremoval-koshishfact-pakistan.doc&ei=STv2T4uhOvO_2QXxwJjaBg&usg=AFQjCNGUyPcn5C4VZdt_mjYo0sheets-0MktUnkw&sig2=yBKPzMiE6wkNRWtSR3kTPg coagulation_fr Household Water Treatment for Arsenic Removal Fact Sheet: Coagulation-Flocculation.] CAWST. (French version).* [http://www.googlesswm.cominfo/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CGkQFjAA&url=ftpsites/default/files/reference_attachments/CAWST%3A202009%2F20Household%2Fftp.wpro.who.int20Water%2Fscratch20Treatment%2FENH20and%2FHWTS20Safe%2FWHO20Storage%2520Final20Fact%2FParticipant20Sheets%2520Manual20Academic%2FAppendices20Arsenic%2FParticipant20Removal%2520Manual_Appendix%25202_HWTS%2520Fact%2520Sheets_2011-09-05%2F6_Arsenic%2520Removal%2FHWTS%2520Fact%2520Sheet_Arsenic%2520Removal_Complexation_2011-0620Complexation.doc&ei=JT32T7b3F4Ow2QW97pn8Bg&usg=AFQjCNHvayfxy_1Ml3uEd_7Y9fhbmyQJcA&sig2=ViTGkFqtns4j4WaOjEVQPQ pdf Household Water Treatment for Arsenic Removal Fact Sheet: Surface Complexation.] CAWST.* [http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CFYQFjAB&url=http%3A%2F%2Fwww.cawst.org%2Fassets%2FFile%2FHWTS_Fact_Sheet_KAF/assets/File/HWTS_Fact_Sheet_KAF.pdf&ei=gz72T6esPOmy2QXl8-ToBg&usg=AFQjCNHExV2LsQy4IgoZzMR2avHnREOnsg&sig2=ClJFwW7vj9UkNrgU-4udPA Household Water Treatment and Safe Storage Factsheet: Kanchan Arsenic Filter.] CAWST.
* [http://www.cawst.org/en/resources/pubs/category/24-fact-sheets-simplified Household Water Treatment Fact Sheets.] CAWST.
