BushProof Biosand Filter
Dr. David Manz, University of Calgary
BushProof biosand filters are a slow sand filtration product for household use.
As of 2018, product training provided in Madagascar, Kenya, Sudan, Congo, Uganda, Somaliland, Afghanistan, Sri Lanka, Pakistan.
Individual filter price varies. BushProof charges $1687.41 USD (1500 EUR) for training on how to build the Biosand filters.
Membrane filtration systems, Community scale purification systems, Point-of-use filtration equipment, Chlorination and other Biosand Filters
Goal 6: Clean water and sanitation
Individuals and households in low-income countries where people rely on untreated, contaminated surface water.
Individual production by artisans and trained builders using locally available materials such as sand, water and cement. BushProof sells metal moulds for casting concrete housings in which the biosand is placed. There are also guidelines for producing moulds. The complete construction manual is available here.
BushProof Biosand filters are sold through trained artisans and builders. BushProof trains individuals to make the systems and sells the moulds required to manufacture the filters.
As of March 2004, BushProof has sold 670 units in Madagascar, Africa: 600 for rural households and 70 in urban households.
BushProof Biosand filters work according to the principles of a general BioSand Filter (BSF) whereby layers of sand and gravel are housed in a concrete container. The water level is maintained above the sand layer by setting the height of the outlet pipe. This shallow water layer allows a bioactive layer to grow on top of the sand, which contributes to the reduction of disease-causing organisms. A diffuser plate with holes in it is placed on the top of the sand layer to prevent disruption of the biolayer when water is added to the system. To use the BSF, users pour water into the BSF, and collect finished water out of the outlet pipe into a bucket.
The BushProof Biosand Filters relies on intermittently operated BSF technology. In this design, the drain pipe is raised 1-8 cm above the sand level, which ensures that the water level is just above the sand. Even when water is not continually added to the filter, oxygen can still permeate into the water to reach the bioactive layer by diffusion across this shallow layer of standing water.
When the flow rate becomes unacceptably low, the filter can be cleaned by removing accumulated dirt from the top few centimeters of sand. There are several ways to do this, but all disturb the biological layer which results in less effective filtration for some time. Some methods are less disruptive than others.
BushProof-trained artisans provide technical support, and an instruction booklet can be accessed online.
All materials are locally available and can be sourced by the builder.
About 4 years according to research conducted by Medair, Kenya
Intermittently-operated slow sand filters can be made as small units that supply clean water for a family. Under ideal conditions, a biosand filter of this size produces 1 liter of clean water per minute. Even at a much slower flow rate, however, the filter can be practical. A filter that fills a 20-liter jerry can in two hours can be convenient to a family, even though this equals a flow rate of only 0.16 liters per minute.
Water, advocacy, sanitation and hygiene: Lessons learnt from Tearfund’s global water, advocacy, sanitation and hygiene programme 2007–2012. Written by Murray Burt and Bilha Joy Keiru.
Concrete filters can be heavy and difficult to move and transport.
Safe water storage containers.
Significant research has been conducted on BSF technology. A comprehensive list is available via CAWST.
Additional examples include: Sangya-Sangam K. Tiwari, et al. Intermittent slow sand filtration for preventing diarrhoea among children in Kenyan households using unimproved water sources: randomized controlled trial. Tropical Medicine & International Health Volume 14, Issue 11, pages 1374–1382, November 2009
Michael Lea. Clearinghouse, Low-cost Water Treatment Technologies for Developing Countries, Ottawa, Ontario, Canada. Biological Sand Filters: Low-Cost Bioremediation Technique for Production of Clean Drinking Water Current Protocols in Microbiology 1G.1.1-1G.1.28, May 2008
Although Biosand filters have been tested to reduce pathogen load in drinking water, they do not consistently comply with WHO standards for drinking water.
Field evaluations. Examples include, Medair Kenya – Biosand filter project evaluation report Results showed that filters were still performing very well, producing drinking water of acceptable purity to the majority of households that bought one 4 years prior.
In 2005, BushProof received the World Bank global Development Marketplace award.
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