Membrane filtration is a physical separation process that purifies, concentrates or fractionates dissolved or suspended species. Under the effect of a driving force, usually pressure, the species of size below the cut off point membrane pass through the membrane pores (permeat) and the larger species are retained (retentat).

The industrial implementation of this separation technique is conditioned to the maintenance of the production flow during filtration. This is ensured by the application of a large circulation speed to control the clogging by sweeping the surface of the membrane: it is called tangential filtration.