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[[Image:CPF1.jpg|thumb|right|150px| Potters for Peace filter model.]]
[[Image:CPF4.jpg|thumb|right|150px| Small local filter factory.]]
Locally produced ceramics have been used to filter water for hundreds of years. Water is poured into a porous ceramic filter pot, and is collected in another container after it passes through the ceramic pot.
Colloidal silver is sometimes applied to the ceramic pot after firing or added to the clay mixture prior to firing. Colloidal silver is an antibacterial which helps in pathogen removal, as well as preventing growth of bacteria within the filter itself. Some ceramic pot filters also include activated charcoal in the clay mixture to improve odour, taste, and colour.
Pathogens and suspended material are removed from water through a combination of biological and physical processes.
Quality control on the size of the combustible materials used in the clay mix ensures that the filter pore size is small enough to prevent contaminants from passing through the filter. Colloidal silver aids treatment by breaking down pathogens’ cell membranes, causing them to die.
==History and social context==
150,000 filters are used in Central America, Asia and Africa.
In Nicaragua, Guatemala and Cambodia the production of this filter is a commercial activity and production is starting up in six other countries.
==How Does It Remove Contamination?Suitable conditions ==Pathogens and suspended material are removed from The ceramic pot filter is suitable to process 8 litres of water through per batch. This produces a combination daily water supply of biological and physical processes20-30 litres. {{Potential_Treatment_Capacity_table| highly=- Bacteria<br>- Protozoa<br>- Helminths<br>- Turbidity<br>- Taste/odour/colour| somewhat= - Viruses<br>- Iron<br>| not= - Dissolved Chemicals| process=Filtration| watcrit=Turbidity < 50 NTU}}
====Operation====
Contaminated water is poured into the ceramic pot. The water slowly passes through the pores and is collected in the lower container. The treated water is stored in the container until needed, protecting it from recontamination. The user simple opens the tap at the base of the container when they need water.
For turbidity levels greater than 50 NTU, the water should first be strained through a cloth or sedimented before using the ceramic filter.
The filter pot should be regularly cleaned using a cloth or soft brush to remove any accumulated material. It estimated flow rate is recommended that the filter pot be replaced every 1-2 years3 litres/hour. This is in part to protect against fine cracks which may have developed highest when the pot is full. It declines with use and are not be visible. Any cracks will reduce accumulation of contaminants within the effectiveness since water can short-circuit through the crack without being filtered through the ceramic filter pores.
====Treatment efficiencyEfficiency====
{{Treatment_Efficiency
|lab:bacteria=>98-100 % <ref name=Lantagne>[[#Lantagne01|Lantagne]] (2001)</ref><ref name=Smith>[[#Smith04|Smith]] (2004)</ref>
Treatment efficiencies provided in the above table require colloidal silver. The treatment efficiency is also affected by pore size and construction quality. Taste, odour and colour of filtered water is generally improved.
====Maintenance====
It is recommended that the filter pot be replaced every 1-2 years. This is in part to protect against fine cracks which may have developed and are not be visible. Any cracks will reduce the effectiveness since water can short-circuit through the crack without being filtered through the ceramic pores.
* Clay
* Combustible material (e.g. sawdust, rice husks, coffee husks)
* Lid
* 20-30 litre ceramic or plastic container with tap
* A ceramic factory requires at least 100 m<sup>2</sup> of covered area
* 15 to 20 ton hydraulic press (can be fabricated locally)
* Miscellaneous tools (e.g. traditional pottery tools)
==Maintenance requirements==Suppliers====Filters Free press and kiln designs are cleaned by lightly scrubbing the surface when the flow rate is reduced. Some manufacturers recommend to boil the filter every three months to ensure effectiveness. Some manufacturers recommend that soap and chlorine should not be used to clean the filter. The lower container, tap and lid should be cleaned on a regular basisavailable from Potters for Peace.
==Cost==
Cost of introduction: US$ 15,000 - 30,000 for project incl. training, machinery and a first production of 500 filters. US$ 50,000 - 100,000 for project incl. production shop, training, first promotion, and 5,000 filters.
==Country experiences==
==Manuals==
* [http://s189535770.onlinehome.us/pottersforpeace/?page_id=125 Complete production manual is available from Potters for Peace]
==Movies==
* Panel Discussion English [http://video.google.com/videoplay?docid=6838040406197916953&hl=en video.google.com/videoplay?docid=6838040406197916953&hl=en ]
==External linksLinks==
*[http://www.cdc.gov/safewater/publications_pages/options-ceramic.pdf Centers for Disease Control and Prevention]
*[http://www.filterpurefilters.org Filter Pure, Inc]
==Footnotes==
<references/>
==References==
* Van Halem, D. (2006) Ceramic silver impregnated pot filters for household drinking water treatment in developing countries. Masters of Science in Civil Engineering Thesis, Department of Water Resources, Delft University of Technology, Netherlands.
* Vinka, A. et al. (2007) Sustainable Colloidal-Silver-Impregnated Ceramic Filter for Point-of-Use Water Treatment, Environmental Science & Technology, Vol. 42, No. 3, 927–933
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