Biological Aerated Filter (BAF)*

A biological areated filter is a submerged media wastewater treatment unit that combines aerobic biological treatment and biomas separation by depth filtration. Wastewater is spread over a collection of relatively large grain or sponge like material and allowed to drain through by gravity. Organic biomass grows quickly throughout the filter depth after start-up, oxidizing organic material and (for instance) nitrifying ammonia in the wastewater as it passes over the biofilm layers. Additional reactions can also take place depending on the configuration of the filter. BAFs are able to operate at higher BOD loadings than, for instance, conventional sand filters and thus require relatively small floor areas.

*This definition was reprinted by permission from the "Dictionary of Filtration and Separation". The "Dictionary" contains over 1500 definitions and 400 diagrams and photos. More information on the "Dictionary" and order form can be found here.

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