There is an undeniable need for clean water throughout the developing world. Every year there are over a million deaths related to unsafe water, sanitation and hygiene, mainly through infectious diarrhea. Over 1.1 billion people lack access to clean water and even more lack access to proper sanitation.
The Bio Sand Filter that we are using in NW Cameroon was designed by Dr. David Manz. It’s a very simple device for household water treatment. David and Camille Dow Baker co-founded the Canadian NGO CAWST to answer the question, "How can we get proven technologies in the hands of the millions that need safe water?" We work as a partner with them and also with Wycliff Associates ( Operation Clean Water ) Both these organisations have many years experience working in this area, and we are pleased to be able to call on their expertise as necessary.
Household water treatment enables clean water to be available for families to use. The BSF works the same way as traditional slow sand filters, which have been used for centuries. The (BSF) filter can be built anywhere in the world because it uses materials that are locally available. The filter housing itself is simply a concrete container, with layers of sand and gravel inside. The Bio Layer at the top part of the Filter is very important. This is where the bad water poured into the filter is essentially” cleaned”.
The Bio Sand Filter is proven to almost entirely remove the disease-causing organisms found in water—pathogens. It removes more than 99.9% of parasites and over 97% of E.coli bacteria (an indicator of fecal contamination). It also removes nearly all suspended sediments.
The Bio sand Filter allows for a sufficient amount of water to be treated for drinking, cooking, and personal hygiene purposes for a typical family. The cost of a concrete BSF varies from country to country depending on the material and labour costs. The cost in NW Cameroon is approx. €25. The largest variable costs include labour and transportation, and depend on local conditions and the distance from the production facility to the end users.
Water For Cameroon programs endeavour to support small businesses be established to produce the BSF’s in the rural villages where we are working in NW Cameroon.
There are no ongoing operating costs required to successfully operate the filter. No, the sand does not need to be replaced!
Education is an essential part of our BSF program. Families who buy a BSF need to understand why bad water causes sickness. Lack of knowledge is the root cause of water borne disease in the majority world.
Knowledge about water, needs to be common knowledge, and available to everyone. We encourage the Business to establish a BSF team, made up of constructors, that is people who actually make the Concrete Filters and install and commission them in the family home. Also to have a specific person who teaches the families about the Principal of the Filter, and why bad water causes sickness.
Water For Cameroon supports the communities in organising informative training programs especially in relation to water Filtration. We are supporting the communities to build capacity amonst themselves to provide continuous water relate services. Our programs are funded mostly by a small and dedicated fundraising team of volunteers in Dublin, Ireland.
See elsewhere on this website to find out how you can help. A little help goes a long way.
The major benefits of slow sand filtration are due to the microbiology of the filter. The microbiological community must be kept alive for the filter to be effective. In a conventional slow sand filter, oxygen is supplied to the organisms through dissolved oxygen in the water. Consequently, they are designed to be operated continuously. Also, because the water moves through at a slow rate, the filter beds tend to be very large.
The biosand water filter is an invention that modifies the traditional slow sand filter in such a way that the filters can be built on a smaller scale and can be operated intermittently. These modifications make the filter suitable for use at the household or small group level. Household use would simply not be possible with conventional slow sand filtration because of the size requirements and the mode of operation. A bucket of contaminated water can be poured into the top of the biosand filter as necessary. The water simply flows through the filter and is collected in another bucket or container at the base of the spout. It normally takes a few minutes for the entire bucket to make its way through the filter.
There are no valves or moving parts and the design of the outlet pipe ensures that a minimum water depth of five centimetres is maintained over the sand when the filter is not in use. When water is flowing through the filter, oxygen is supplied to the biologic layer at the top of the sand by the dissolved oxygen in the water. During pause times, when the water is not flowing, the oxygen is obtained by diffusion from the air and by slow convective mixing of the layer of water above the sand. If this layer is kept shallow, enough oxygen is able to pass through to the micro organisms to keep them alive and thus effective.
The filter is made up of five distinct regions; the influent reservoir, the supernatant, the schmutzdecke, the biologically active zone, and the sand support and underdrain, as shown below.