In this study membrane filtration processes, e.g. micro-, ultra- and nanofiltration, have been considered from an application directed point of view set by the pulp and paper industry. Three different shear-enhanced modules are compared. The modules are the vibration shear enhanced processing (VSEP:) unit from New Logic Int., the compact tubular modules from Stork-Friesland and the cross rotational (CR) filter from Raisio Engineering. The paper mill waters studied have been the save-all (disc filter) clarified fractions of white water resulting from either an acidic or a neutral paper making process. A feasible membrane filtration process in the pulp and paper industry means high flux and low fouling tendency. In this study it is shown that optimized operation of the shear-enhanced modules fulfils these requirements. Optimization is done by selecting relatively low pressure and high flow velocity and/or high shear at the membrane/liquid interface. Moreover, the flux can be further increased by using chemical pretreatment. A relatively low dosage (0.5 mg/l) of a fixative (Raifix: 07525) was needed to increase flux about 20% and reduce irreversible fouling significantly. It was further seen that ultrafiltration produces permeate that is usually clean enough for recycling purposes in the paper mill. However, if ion content is to be reduced, only nanofiltration qualifies. In addition, ultrafiltration, in most cases, produced higher fluxes than microfiltration because microfiltration membranes are more apt to foul in this application.