Desal

Desalination, often shortened to desal, refers to processes that remove dissolved salts from saline water to produce fresh water. It is used where freshwater supplies are limited or stressed, particularly in arid coastal regions.

Two main families are thermal desalination and membrane desalination. Thermal methods, such as multistage flash and multi-effect distillation, use heat to evaporate water. Membrane methods, dominated by reverse osmosis, use high pressure to force water through semi-permeable membranes, leaving salts behind.

Feedwater is pretreated to remove particulates and scale-forming compounds; after treatment, the product water may be remineralized to restore essential minerals and disinfected to meet drinking-water standards.

Desalination is energy-intensive and costly, though energy recovery devices and the integration of renewables are reducing impacts. Environmental concerns include intake of plankton and small organisms and the management of brine, which is often diluted or diffused before discharge to mitigate effects on marine ecosystems.

Globally, desalination capacity has expanded since the mid-20th century, with widespread use in water-stressed regions such as the Middle East, parts of North Africa, Australia, and coastal areas of the United States and Europe. Advances in efficiency, permitting processes, and environmental safeguards continue to shape its deployment and public acceptance.