A predictive model for the removal of colloidal particles in fibrous filter media

The effective medium approximation (EMA) has been applied to a flow through a porous medium filled with fibrous collectors for the prediction of permeability and the removal (or filtration) rate of colloidal particles. The new EMA model, which assumes that a cylindrical collector is surrounded by a uniform layer of fluid and by an effective medium beyond the fluid layer, provides a representative flow field around a cylindrical collector by which the permeability of the fibrous filter medium and its particle removal rate can be determined. The permeability predicted by this new model is shown to be in better agreement with experimental results and numerical calculations than those predicted by other existing models such as cell model and Brinkman’s model. It is also found that the predicted removal rate of colloidal particles by a fibrous filter medium is also in excellent agreement with the results of numerical calculation.