Desalination

Desalination is a process that removes dissolved minerals (including but not limited to salt) from seawater, brackish water, or treated wastewater. Desalination plants may use seawater (directly from the ocean through offshore intakes and pipelines, or from wells located on the beach or seafloor), brackish groundwater, or reclaimed water as feed water. Since brackish water has a lower salt concentration, the cost of desalting brackish water is generally less than the cost of desalting seawater. In desalisnation plants that produce water for domestic use, post-treatment proceses are often employed to ensure that product water meets the health standards for drinking water as well as recommended aesthetic and anti-corrosive (corrosion control) standards. The desalinated product water is usually more pure than drinking water standards, and also highly acidic so when product water is intended for municipal use, it may be mixed with water (water quality) that contains higher levels of total dissolved solids or adjusted for pH, hardness and alkalinity before supply. The product water recovery relative to input water flow is 15 to 50% for most seawater desalination plants.

The technologies generally adopted for the desalination of saline water into fresh water, are as follows:

i.   Distillation,

ii.  Demineralization,

iii. Reverse Osmosis

iv. Electrodialysis