Fouling Phenomena in Microporous Membranes: Flux Decline Kinetics and Structural Modifications

The fouling mechanisms in microfiltration are analyzed with two symmetric and one asymmetric membranes. Fouling kinetics when microfiltering bovine serum albumin solutions (BSA) are studied for both the consecutive processes of surface blocking and cake formation. Influence of shear stresses and aggregates is analyzed.

Permeate flux is recovered by cleaning with different agents and temperatures, thus with different removal and cake coagulation performances. Finally, modifications of the structure of the porous matrix due to the appearance of a cake on the retentate layer of the membrane are studied by air permeation porometry. The flux decay and recovery characteristics as well as the structural modifications obtained agree with the two consecutive steps in the fouling mechanism leading to a solute accumulation on the pore entrances whose consequences are analyzed here.

This model predicts asymmetries in the recovered water flux after cleaning which are effectively found.