Bio Sand Filter - Filtration Process

Filtration Process

Pathogens and suspended solids are removed through a combination of biological and physical processes that take place in the biolayer and within the sand layer. These processes include:

• Mechanical trapping. Suspended solids and pathogens are physically trapped in the spaces between the sand grains.
• Predation. Pathogens are consumed by other microorganisms in the biolayer.
• Adsorption. Pathogens become attached to each other, suspended solids in the water and the sand grains.
• Natural death. Pathogens finish their life cycle or die because there is not enough food or oxygen for them to survive.

As was referenced earlier, different processes occur during different points in the filter running process. These can be broken down into segments of the filter running process: the pause period (idle time) and actual run of the filter.