What are the two methods commercially available for the desalinization of water? How do they work?

The two commercial methods of desalinization are

Membrane RO (Reverse Osmosis)

Thermal MED, MSF

Explanation:

Membrane RO:

It is an industrial water filtration treatment process in which water pressure is applied against feed water forcing it to pass through a semi-permeable membrane to isolate the water molecules from other inorganic impurities and pollutants (salts, nitrates, pesticides, sulfates, fluoride, bacteria, pharmaceuticals, arsenic and much more) that are contained within water. This process is carried out to produce potable water (Drinking water).

MED:

A Multi-Effect Desalinization MED is a Thermal desalinization process comprised of MED unit which evaporates seawater in one or more evaporation stages (up to 14 stages) at low temperatures (less than70°C) in order to produce pure, clean and distilled water.

MSF:

Multi-stage Flash Distillation is a thermal desalinization process in which the water is distilled by boiling it under vacuum (flashing) and then condensing it by the pure water vapor. Multiple shells and tube heat exchangers called stages are used to produce the Potable water.