5. Fixed submerged culture beds (biofilters)

5.1 Theoretical background on fluid flow in porous media

The passage of water through a porous material results in significant energy dissipation.

• Hydraulic pressure drop

  The resulting hydraulic head loss is usually measured in water head and depends on many factors, such as water flow velocity, fluid viscosity and the permeability of the filter material. In 1856, Henry Darcy discovered the relationship between water flow velocity and the pressure gradient imposed on either side of the porous material. His research led to the formulation of Darcy's Law, a tool for calculating pressure drop during the slow flow of a fluid through a porous medium that is homogeneous and isotropic, as illustrated in equation 1....