KAGAKU KOGAKU RONBUNSHU, Vol.35, No.1, 81-86, 2009
Microfiltration of Incompressible Particle Suspension with an Asymmetric Depth Filter
Depth filters trap particles internally, and thus the compaction of the particle layer is partially repressed by the internal structure of the filter to yield a high permeation flux at a low transmembrane pressure. We filtered suspensions of three kinds of polystyrene latex particles (incompressible, spherical, 0.30, 0.54, and 0.70 mu m in diameter) with an asymmetric depth filter, SE20 (nominal pore size=0.20 mu m), at different transmembrane pressures and concentrations. The filtration resistance per unit weight of trapped particles with the depth filter was half of that with a screen filter in the filtration of latex particles. The particles were trapped first near the outlet side of the filter and then near the inlet side, unlike the standard blocking model for the membranes with cylindrical pores and the deep bed filtration model for sand filtration. A filtration model was proposed for the filtration of latex suspension with the depth filter. The model suggested that the asymmetric depth filter showed high performance because the filaments in the filter increased the porosity of the particle layer in contact with them.