Two main technologies are applied nowadays in desalination projects:
I. Membrane Technologies (60%)
Reverse osmosis is a process used to purify concentrated solutions of dissolved minerals and salts and is used in desalination plants. Reverse osmosis involves forcing water through a semi-permeable membrane under high pressure, leaving the dissolved salts and other solutes behind on the surface of the membrane. Source: water-technology.net
II. Distillation Technologies (34%)
A. Multi-Stage Flash Distillation
An evaporator consists of several consecutive stages (evaporating chambers) maintained at decreasing pressures from the first stage (hot) to the last stage (cold). Sea-water flows through the tubes of the heat exchangers where it is warmed by condensation of the vapor produced in each stage. Thus it will immediately “flash” i.e. release heat, and this vapor, to reach equilibrium with stage conditions. The produced vapor is condensed into fresh water on the tubular exchanger at the top of the stage. Source: SIDEM
B. Vapor-Compression Desalination
In this process a mechanical compressor provides the energy source and produces its own steam used as the heat source.
C. Multiple-Effect Distillation
A Multi-Effect Desalination (MED) unit is an evaporator where sea water is evaporated in one or more ( up to 14 ) evaporation stages at low temperature ( < 70°C ) in order to produce clean distillate water.
MED process is designed to produce distilled water with steam or waste heat from power production or chemical processes, and/or to produce potable water. Source: Entropie