![[We need] a farsighted program for meeting urgent water needs by converting saltwater to fresh water. Dwight D. Eisenhower, 1951](img/blocks/about desal.jpg)
about desalination > desalting process
The two most common technologies used to desalt seawater are membrane and thermal processes. Membrane processes can be either reverse osmosis (RO) or electrodialysis (ED).
RO is a proven technology in many plants operating throughout the world and is the recommended technology for the Coquina Coast project. RO uses high pressure pumps to force seawater through a semi-permeable membrane that removes salt from seawater to produce fresh drinking water. The pore size of an RO membrane is very small, usually less than .0001 micron, which is about one one-millionth the diameter of a grain of sand. RO membrane pores are so small that salt molecules, bacteria, viruses and other microscopic materials are filtered out. Technological advances in recent years have brought down the production cost of reverse osmosis desalination, making this alternative more cost-competitive with other alternative water supplies.
Electrodialysis uses an electrical current to separate out salt and impurities through the use of a semi-permeable, ion-selective membrane. ED is typically used to desalt brackish water at the municipal scale but has been used for seawater.
Thermal distillation is the oldest known method of desalinating seawater. In the thermal process, seawater is heated to generate water vapor. The vapor is condensed to liquid form containing very little of the original salt.
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