Inverse penetration refers to the concentrated solution side places a greater than the pressure of saturated pressure, solvent in concentrated solution would be to dilute solution, the solvent activity direction contrary to soak in the direction of the original, this process is called the penetration; This principle is used for liquid separation, for purification, addition of miscellaneous, and treatment of liquid substances
The principle of anti-saturating film: the membrane is called a semi-permeable membrane through which the material is selected. The membrane is usually referred to as an aspirational semi-permeable membrane through the solvent rather than through the membrane of the solute. When the same volume of dilute solution (such as fresh water) and concentrated solution (brine, for example) into a semipermeable membrane separation on both sides, the solvent in the dilute solution of natural through a semipermeable membrane and consciously to the concentrated solution on one side of the activity, the surface is called penetration. When the saturation reaches the equilibrium, the liquid surface on the side of the concentrated solution will be higher than the liquid surface of the dilute solution, which is to form a differential pressure, which is the penetration pressure. Campaign against soak is soaked with a reverse move, is a pressure driven by a semipermeable membrane choosing intercept effect of solute and solvent separation from the solvent separation method, it has been widely used in all kinds of purification and concentration of solution, in which the use of the most common example is in the water treatment skills, drenched in the skill will inorganic ions, bacteria, viruses and organic matter in raw water and colloidal impurities, in order to obtain high quality of pure water.