Bio Sand Filter

Bio Sand Filter

According to the World Health Organization, about 1 billion people in developing countries lack access to a clean water supply. Biosand filters (BSF) are a point of use filtration system, developed from slow sand filters, which remove pathogens and suspended solids from water. As compared to other point of use systems, such as chlorination or solar disinfection, BSFs are easier to operate, and less expensive, which makes them a good alternative, especially in developing countries.

Biosand filters remove pathogens and suspended solids through a combination of biological and physical processes that take place in the biolayer and within the sand column. BSFs have been shown to remove 5.00-64.00% of heavy metals and 90.00-99.99% of turbidity and contaminants such as bacteria, viruses, and protozoa. BSFs also help to reduce discoloration, odor, and unpleasant taste. Studies have also shown a decrease in the occurrence of diarrheal disease and an increase in general health, correlated with the use of BSFs. It is estimated that over 200,000 BSFs are in use world wide.

Biosand filters are typically constructed from either concrete or plastic. The most widely used plans for the concrete biosand filter are produced and distributed by the Center for Affordable Water and Sanitation Technology (CAWST) in Calgary. Hydraid, which works with Cascade Engineering and Triple Quest, focuses on plastic BSFs. TivaWater introduced a low cost plastic filter that incorporates a 20 liter storage container to prevent contamination, a tapered design that slows filtration and increases purity, and uses a pre-filter cloth to minimize clogging.