General presentation

Reverse osmosis, nanofiltration, ultrafiltration and tangential microfiltration are all liquid phase separation processes involving permeation through permeable membranes under the action of a pressure gradient.

As a reminder, a permselective membrane is a barrier that allows certain transfers of matter between two media it separates, while preventing others or, less restrictively, favoring some over others.

These processes use membranes whose pore diameters progressively decrease as we move from microfiltration to ultrafiltration, then to nanofiltration (figure 1...