Slow Sand Filtration

 

         [Images from lifewater.org(USAID)]

Most filtration systems produced commercially are expensive and labor/maintenance intensive.  However, there are a couple of simple filtration processes that require a minimum of external inputs and expertise for continued operation and maintenance.  For example, passing drinking water through a double layer of thin fabric will remove the guinea worm, an important parasite in many parts of Africa (Peace Corps, 2003).  This is a very specific and simple technology appropriate only in places known to have a single problem, the guinea worm.  In places with more common drinking water problems, such as protozoa, bacteria, viruses, and chemical contaminants, the slow sand filtration system may be a good treatment technology for a small community or village.

 

 

Jordan (1980) provides a quick explanation and further references on how to construct a slow sand filter in a rural community.  The slow sand filter is a good solution, provided the materials are available for construction and the water flow through the filter is small enough.  Although the quality of filtered water is typically good, Jordon (1980) reports that the slow sand filter can only filter 7-11 liter/hour, per square meter of filter surface area.  This is an important consideration when installing such a filter in a rural community.

 

Links and Resources:

This link has information about all sorts of water issueswith special reference to larger scale slow sand filtrationschemes:

* http://www.hortips.co.uk/hns_2.htm

 

Provides step by step instructions for design and

construction of slow sand filters for families or

small communities:

*  http://www.lifewater.org/wfw/rws3/rws3m.pdf

 

General information about slow-sand filtration:

*http://www.nesc.wvu.edu/ndwc/pdf/OT/TB/TB14_slowsand.pdf

*http://water.shinshu-u.ac.jp/e_ssf/e_ssftop.htm

*http://www.awwarf.com/exsums/90578.htm

*http://www.dayton-knight.com/slow_sand_filtration.htm

*http://www.environmental-center.com/magazine/nrc/jees/s02-025.pdf

 

[Images from lifewater.org(USAID)]