REVERSE OSMOSIS
High pressure liquid solution water is extracted by using asymmetric membranes. But they impede dissolved salts and organic molecules passage. Operation pressure varies between 14 and 70 bar.

NANOFILTRATION
It is similar to reverse osmosis, save that monovalent ions pass through the membrane as water does. Usually surface unit production is more important than R.O. membranes. Operation pressures are defined between 14 to 35 bar.

ULTRAFILTRATION
It performs organic molecules in solution separation under low pressures.
Only certain molecules pass through the membrane. For instance, molecules as sugar pass, proteins do not. These membranes are qualified according to the molecular weight: of the eliminated molecules, giving rise to the so called cut point of the membrane. Operation pressures between 2,5 to 10 bar.

MICROFILTRATION
With pore size between 0,1 and 5,0 micron they are membranes domed to remove only suspended material as distinguished from R.O.; U.F. and N.F. that separate substances in solution too. Microorganisms in general may be M.F. Operation pressures between 0,30 and 3,5 bar.