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How does desalination make seawater suitable for household use and irrigation?

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water rapids, Niagara Falls, Canada — water Water is the most plentiful compound on Earth and is essential to life. Although water molecules are simple in structure (H₂O), the physical and chemical properties of water are extraordinarily complicated.

Desalination is the process of removing dissolved salts from seawater, brackish water, or wastewater to make it suitable for human consumption and irrigation. This is achieved primarily through two types of technologies:12

Thermal Processes

These methods involve heat transfer and a phase change, such as evaporation or freezing.32
* Distillation: Seawater is heated to create vapor, which is then condensed into fresh water, leaving the salt behind. Multistage flash distillation is a common large-scale method that uses a series of chambers at progressively lower pressures to boil water repeatedly without requiring additional heat at every stage.31
* Solar Humidification: Sunlight vaporizes salt water under a cover; the vapor condenses on the underside and is collected as fresh water.13
* Freezing: Salt water is cooled to form pure ice crystals, which are separated from the brine and melted into fresh water.3

Membrane Processes

These methods use semipermeable materials to separate salt from water.12
* Reverse Osmosis: Salt water is forced against a membrane under high pressure. Fresh water passes through the membrane, while concentrated salts are left behind.14
* Electrodialysis: An electrical potential drives salt ions through selective membranes, leaving fresh water between the filters.14