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Kanchan Arsenic Filter

957 bytes added, 23:35, 20 May 2015
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[[Image:CAWST_Kachan.png|thumb|right|300px| Cross-section through a Kachan Arsenic Filter]]
[[Image:CAWST_KachanThe Kanchan Arsenic Filter (KAF) is an adaptation of the biosand filter (BSF).png|thumb|right|150px| CrossIt 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-section through a Kachan Arsenic Filter]]galvanized nails in the diffuser basin of the filter.
The Kanchan Arsenic Filter This filter was developed by researchers at Massachusetts Institute of Technology (MIT), Environment and Public Health Organization (KAFENPHO) is an adaptation of the biosand filter Nepal, and Rural Water Supply and Sanitation Support Programme (BSFRWSSSP). 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 rusty nails in the diffuser basin of the filterNepal.
The filter container can be constructed out ===Suitable conditions===It is suitable to process batches of concrete or plastic12-18 litres. The container is about 0.9 m tall and either 0.3 m square or 0.3 m in diameterIf two batches a day are filtered, this provides 24-36 litres of clean water.
The container is filled with layers of sieved and washed sand and gravel (also referred to as filter media). There is a standing water height of 5 cm above the sand layer. {{procontable | pro= Similar to in slow sand filters- Can remove arsenic, a biological layer of microorganisms (also known as the biolayer or schmutzedecke) develops at the sand surfacepathogens, which contributes to the iron and turbidity from drinking water treatment. <br> The diffuser basin is filled with 5 to 6 kg of non-galvanized iron nails for arsenic removal. A layer of bricks on top of the nails prevents displacement of the nails when water is poured into the filterConstructed by trained local technicians using local materials.<br> - Good flow rate (15-20 litres/hour) <br>Arsenic from the water is rapidly adsorbed onto the rust on the iron nails. The rust - Simple operation and arsenic flake off the nails, and are caught in the sand filter and retained. maintenance (O&M) <br>- This KAF is a very tight bond; re-suspension constructed of arsenic into simple materials available on the water, or relocal market <br>-mobilization The construction of the arsenic from the waste produced from cleaning the filter has shown to can be negligible.carried out by locally trained technicians <br>| con= - Does not provide residual protection to minimize recontamination <br>In addition, pathogens, iron and suspended material are - Filter should not be removed from water through a combination of biological and physical processes. These after installation because cracking or breakage may occur both in both the biolayer and within the sand bed. These processes include: mechanical trapping, adsorption/attraction, predation and natural death.<br>- Waste isolation <br>==History and social context== ==Suitable conditions ==It is suitable to process batches of 12-18 litresChanging water sources (esp. If two batches a day are filtered, this provides 24-36 litres to rainwater) may compromise removal of clean water. arsenic <br>}}
{{Potential_Treatment_Capacity_table
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==Technical specification=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.  The container is filled with layers of sieved and washed sand and gravel (also referred to as filter media). There is a standing water height of 5 cm above the sand layer.  Similar to in slow sand filters, a biological layer of microorganisms (also known as the biolayer or Schmutzdecke) develops at the sand surface, which contributes to the water treatment.  The diffuser basin is filled with 5 to 6 kg of non-galvanized iron nails for arsenic removal. A layer of bricks on top of the nails prevents displacement of the nails when water is poured into the filter. Arsenic from the water is rapidly adsorbed onto the rust on the iron nails. The rust and arsenic flake off the nails, and are caught in the sand filter and retained. This is a very tight bond; re-suspension of arsenic into the water, or re-mobilization of the arsenic from the waste produced from cleaning the filter has shown to be negligible. In addition, pathogens, iron and suspended material are removed from water through a combination of biological and physical processes. These occur both in both the biolayer and within the sand bed. These processes include: mechanical trapping, adsorption/attraction, predation and natural death.
====Operation====
Sand and iron nail selection and preparation are critical to ensure flow rate and treatment. Filters should not be moved after installation.
 
====Manufacturing====
Local production of filters is most common. Molds can be borrowed, rented, bought or constructed locally. Filters can be constructed at a central production facility, or in the community. Filter sand and gravel can be prepared (sieved and washed) on-site or nearby.
 
Materials and facilities required are:
*Steel mold
*Sand, gravel, and cement
*Filter sand and gravel
*Copper or plastic outlet tubing
*Metal or plastic for the diffuser basin
*5-6 kg of non-galvanized iron nails
*Metal or wood for the lid
*Water for concrete mix and to wash filter sand and gravel
*Miscellaneous tools (e.g. wrench, nuts, bolts)
*Facilities: Workshop space for filter construction
 
A skilled welder required to fabricate molds. Anyone can be trained to construct and install the filter. Individual householders can assist in constructing their own filters.
 
Working with cement and heavy molds is potentially hazardous and adequate safety precautions should be used. Concrete filters are heavy and difficult to move and transport.
====Treatment Efficiency====
The outlet should also be cleaned regularly using soap and water or a chlorine solution.
 
====Manufacturing====
Local production of filters is most common. Molds can be borrowed, rented, bought or constructed locally. Filters can be constructed at a central production facility, or in the community. Filter sand and gravel can be prepared (sieved and washed) on-site or nearby.
 
Materials and facilities required are:
*Steel mold
*Sand, gravel, and cement
*Filter sand and gravel
*Copper or plastic outlet tubing
*Metal or plastic for the diffuser basin
*5-6 kg of non-galvanized iron nails
*Metal or wood for the lid
*Water for concrete mix and to wash filter sand and gravel
*Miscellaneous tools (e.g. wrench, nuts, bolts)
*Facilities: Workshop space for filter construction
 
A skilled welder required to fabricate molds. Anyone can be trained to construct and install the filter. Individual householders can assist in constructing their own filters.
 
Working with cement and heavy molds is potentially hazardous and adequate safety precautions should be used. Concrete filters are heavy and difficult to move and transport.
====Estimated Lifespan====
====Suppliers====
Free mold designs are available from CAWST.
==Cost=Costs===
{{Treatment_Cost
|CapCost=US$ 12-30
Note: Program, transportation and education costs are not included.
==Country =Field experiences== ==Manuals== ==Movies==
==External LinksReference 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.
==References==
* <cite id=Buzunis95>Buzunis, B. (1995). Intermittently Operated Slow Sand Filtration: A New Water Treatment Process. Department of Civil Engineering, University of Calgary, Canada.</cite>
* <cite id=Uy08> Uy, D., Chea, S., Mao, S., Ngai, T. and T. Mahin (2008). Kanchan Arsenic Filter - Evaluation of Applicability to Cambodia - Phase I Technical Report. Cambodian Ministry of Rural Development and the Institute of Technology of Cambodia.</cite>
 
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