COLLOIDAL FOULING DURING ULTRAFILTRATION

Colloidal fouling causes serious problems in many membrane plants. Two different kinds of flux-reducing phenomena occur when treating colloi dal dispersions, When treating stable dispersions the flux is reversib le and can be restored after changing the operating parameters, such a s the transmembrane pressure or the crossflow velocity. The flux reduc tion experienced when treating unstable colloidal dispersions is irrev ersible. In this study the DLVO theory, well-known from colloid chemis try, has been used to illustrate the mechanisms underlying the differe nce in filtration characteristics between stable and unstable colloida l dispersions.