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| {{copyvio|from http://www.meribah-ram-pump.com/downloads/Flyer-Waterfilter.pdf - have the copyright holders explicitly allowed its use under CC-BY-SA?}} | | {{topic page needed}} |
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| ==Maintenance==
| | {{cat header| default.png | {{subst:PAGENAME}} | Please click edit and add an intro sentence here. }} |
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| There is some key maintenance that is required after a filter has been installed and used regularly.
| | And delete the open and close tags of this "comment-out" section too: --> |
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| ===Arsenic Removal===
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| The bio sand filter can remove a certain level of arsenic from water by adding non-galvanized iron nails, covered by a layer of brick chips.
| | == External links == |
| | | * [http://www.raintree-foundation.org/AT/Appropirate_Technologies/Bio_Sand_Filter.html Biosand Filter] |
| The diffuser plate is replaced with a deep diffuser basin that can hold the nails and brick chips. The iron nails will quickly rust after contact with water and air.
| | * [http://www.wcponline.com/pdf/October2012Kearns.pdf] Sustainable Decentralized Water Treatment for Rural |
| | | and Developing Communities Using Locally Generated Biochar Adsorbents (879kb pdf) |
| Iron rust (ferric hydroxide) is an excellent adsorbent for arsenic. When arsenic-containing water is poured into the filter, surface reactions with the iron occurs, and arsenic is rapidly adsorbed onto the surface of the rusty nails.
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| The arsenic loaded iron particles are then flushed down and trapped on top of the sand layer. The brick chips help to evenly disperse the water over the nails to allow for further absorption.
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| ==The Bio Sand Waterfilter== | |
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| The bio sand filter has six different distinct zones:
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| ===Meribah Bio Sand Waterfilter===
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| # Inlet Reservoir: Space above the sand and gravel media which allows for a full pail of water.
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| # Standing Water: Oxygen diffuses through the standing water to the bio layer.
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| # Bio layer: Layer of slime, sediment, and microorganisms which develops at the top 1-2 cm (0.4-0.8”) of the sand surface.
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| # Biological Zone: Develops at the top 5-10 cm (2-4”) of the sand surface. The sand absorbs pathogens, iron, and other small particles.
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| # Sand Zone: Contains virtually no living microorganisms due to lack of nutrients and oxygen.
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| # Gravel Zone: Holds the sand in place which protects the outlet pipe from clogging and allows for the smooth flow of water.
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| ==The Results==
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| Overall, studies have shown that the Bio Sand Filter removes:
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| * > 97% of E. coli - an indicator of fecal contamination (Duke, 2006; Stauber, 2006)
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| * > 99% of protozoa and helminths (Palmateer, 1999)
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| * 80-90% of viruses (Stauber, 2005)
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| * 50-90% of organic and inorganic toxicants (Palmateer, 1999)
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| * 90-95% of iron (Ngai, 2007)
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| * Most suspended sediments
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| Based on slow sand filter research, the bio sand filter may also remove some heavy metals (Muhammad, 1997; Collins, 1998).
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| There is also a design modification known as the KanchanTM Arsenic Filter that is effective in removing both pathogens and 85-90% of arsenic from source water (Ngai, 2007).
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| ==Links==
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| * [http://www.raintree-foundation.org/AT/Appropirate_Technologies/Bio_Sand_Filter.html Biosand Filter]
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| ** Clean Drinking Water
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| ** Easy to Use
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| ** Self contained Maintenance
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| ** For Everybody
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| ** No Following Costs
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| ** Reliable
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| [[Category:Water_treatment]] | | [[Category:Water filtration]] |
| [[Category:Filters]] | | [[Category:Filters]] |
