This page is for existing technology as it applies to Evoke topicsEdit
BioSand Filters. BSF’s are easily made highly efficient purifiers/ filters. There is a difference between a Purifier and a Filter. A filter screens out critters such as Cryptosporidium, Giardia lamblia(North America) and the all time favorite E. coli. Filters will not eliminate viruses though. Generally a chemical is used to eliminate any kind of viral threat. In extreme conditions chemicals such as bleach or iodine may be in short supply. Enter the BSF. In a nutshell, the filter is filled with sand. As the water is poured over the top of the sand it passes an active biological layer (Schmutzdecke) that begins to feed on some of the micro organisms. As the water continues toward the bottom of the filter, much of the viruses attach or bind with the grains of sand where they are attacked by naturally occurring anti-viral compounds created by the Schmutzdecke. After the water passes through the bottom of the filter, it flows upward through a pipe and is taken off by the end user.The BSF is a simple to build, simple to use method of efficiently making water potable.Here are some helpful links:BioSand Filter.org Check out the download section for great PDFs on how to build.Bushproof A for profit company that works with many NGO’s in many locationsCMS-UK Another org. that builds BSF’s as part of their mission work.