MICROFILTRATION MODEL CONSIDERING INCOMPLETE PORE BLOCKING AND INCOMPLETE CAPTURE OF PARTICLES BY CAKE

It is often observed that microfiltration processes depend on particle concentrations in suspensions. There is, however, no filtration model which is applicable to the wider range of particle concentrations, especially an intermediate one. We propose a new filtration model applicable to the entire range of dilute to dense suspensions when the particle size in the suspension is larger than the membrane pore size. This new model consists of two models. One is called the incomplete pore-blocking model, which is a combination of a complete blocking model and a cake-filtration model, and has the capability of estimating the pore-blocking efficiency from experimental data as a function of particle concentration. The other is a particle capture model which introduces the particle collection efficiency of a unit particle layer in a cake. From an investigation of experimental data from constant-pressure batch filtrations of monodispersed latex-particle suspensions, the following observations were made; (1) incompleteness of pore blocking by the particles became larger at higher particle concentrations, and (2) the probability of particles passing through a unit particle layer in the cake was about 5% and did not depend on the particle concentration. This new model allowed us to estimate the final blocking ratio of the membrane pores for the first time.