A biosand filter (BSF) is a point-of-use water treatment system adapted from traditional slow sand filters. Biosand filters remove pathogens and suspended solids from water using biological and physical processes that take place in a sand column covered with a biofilm. (Wikipedia)
Different BSF sizes & materials :
How a bio-sand filter works ?
Video by : Samaritan’s Purse
Pathogens and suspended solids are removed by biological and physical processes that take place in the biolayer and the sand layer. These processes include:
- Mechanical trapping: Suspended solids and pathogens are trapped in the spaces between the sand grains.
- Predation: Pathogens are consumed by microorganisms in the biolayer.
- Adsorption: Pathogens are absorbed into each other and to suspended solids in the water and sand grains.
- Natural death: Pathogens finish their life cycles or die because there is not enough food or oxygen. (Wikipedia)
Now, it’s time for the juicy part : How to make a professional Bio-sand filter ?
There are 100s of DIY videos on Youtube on how to make a Bio-sand filter, but most of them are not enough to get the whole scientific and technical idea behind the BSF.
Don’t get me wrong, you don’t have to be an engineer or a technician to understand it .
Just read this AMAZING PDF file I found online by CAWST, explaining the very basics of the BSF… Check out the content :
- PART 1: WHAT IS A BIOSAND FILTER?
- The Multi-Barrier Approach to Safe Drinking Water
- What is a Biosand Filter?
- How Does a BSF Work?
- The Parts of a BSF
- What Does Each Part Do?
- How Does the BSF Make Water Safe?
- What Happens to the Pathogens and Dirt in the Filter?
- What Makes the BSF Special? The Biolayer!
- What Kind of Water Can I Use?
- What Should I Check When I Visit a Filter?
- PART 2: BIOSAND FILTER CONSTRUCTION MANUAL