Reverse osmosis, also known as reverse osmosis, a pressure difference as a driving force, from the solution separation of the solvent membrane separation operation. Pressure is applied to the material of the membrane side, and when the pressure exceeds its osmotic pressure, the solvent will reverse the reverse direction of the natural permeation. So that a permeated solvent, i.e., a permeated liquid, is obtained on the low pressure side of the membrane; and a concentrated solution, i.e., a concentrated liquid, is obtained on the high pressure side. If the seawater is treated with reverse osmosis, fresh water is obtained on the low pressure side of the membrane and brine is obtained on the high pressure side.
Reverse osmosis usually uses asymmetric membranes and composite membranes. Reverse osmosis equipment used, mainly hollow fiber or roll membrane separation equipment.
Reverse osmosis membrane can be retained in the water of various inorganic ions, colloidal substances and macromolecules solute, in order to obtain net water. It can also be used for preconcentration of macromolecule organic solutions. Because the reverse osmosis process is simple and low energy consumption, it has been widely used in seawater and brackish water (see brine) desalination, boiler water softening and waste water treatment, and combined with ion exchange to produce high purity water, its application is expanding Began to be used for the concentration of dairy products, fruit juice and biochemical and biological agents in the separation and concentration.