MEMBRANE FILTRATION CONSIDERING PORE AND PARTICLE SIZE DISTRIBUTION
Pore and particle size distribution, cake, straining, residual flux
The modeling of filtration process, during the transport of suspended particles in porous medium, is an important and complex process (due to different retention mechanisms such as straining, electric forces, diffusion, etc.) with different industrial applications. Therefore, retention due to size exclusion (straining) was studied as an effective mechanism in the filtration process. The retention mechanism by size exclusion occurs when a particle reaches a smaller pore than itself, causing the retention of particles of the contact phase with the membrane. Thus, the pore and particle size distributions showed strong influence on the filtration process and pore blocking. However, most of the models proposed for direct filtration using membranes do not incorporate such distributions. In this work, the model proposed by Santos et al. (2008) was used, which incorporates the particles and pores size distributions, and proposes analytical solutions to the retention mechanism for size exclusion. Two analytical solutions were proposed considering pore blocking kinetics and cake growth. These solutions were applied considering tests at ΔP=cte and Q=cte, to predict the evolution of pore blocking (caused by different particle sizes) and the consequent flow decline, as well as the increase of pressure during direct microfiltration in membranes. The analytical solutions obtained showed a more realistic behavior than the traditional models, and such solutions were used to adjust the experimental data that presented a good fit.