Concentration polarization merely temporarily increases the concentration of retained substances on the membrane surface. It is a reversible process and does not directly cause membrane fouling. However, it is precisely the existence of concentration polarization in the membrane process that leads to a relative increase in the concentration of retained substances on the membrane surface. This either accelerates the formation of a gel layer on the surface of porous membranes (such as microfiltration and ultrafiltration) or accelerates the saturation and precipitation of sparingly soluble salts on the surface of dense membranes (such as reverse osmosis and nanofiltration), thereby exacerbating fouling of various types of membranes.

For porous membranes like microfiltration and ultrafiltration, the concentration polarization layer formed on the membrane surface also has a certain filtering and retention effect. It can, to some extent, improve the separation membrane's efficiency in retaining solutes and correspondingly increase the solvent permeation resistance. For dense membranes like nanofiltration and reverse osmosis, concentration polarization increases the salt concentration on the retentate side, increases the osmotic pressure on the retentate side, meaning it increases the resistance to water production and reduces the product water flux. Since the permeation rate of inorganic salts is proportional to the salt concentration difference across the membrane, the concentration polarization phenomenon also increases the permeation rate of inorganic salts and reduces the desalination rate of the membrane process.

The main methods to avoid concentration polarization include reducing the pressure difference across the membrane, which can alleviate already formed concentration polarization; and increasing the turbulence level at the membrane surface to reduce the solute concentration at the membrane surface.