Low-temperature Thermal Desalination Technology

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The Chennai-based National Institute of Ocean Technology (NIOT) is working on making an ongoing initiative of providing potable water in six islands of Lakshadweep using a Low-Temperature Thermal Desalination (LTTD) technology process free of emissions.

About Low-temperature thermal desalination Technology:

  • The LTTD is a process under which the warm surface seawater is flash evaporated at low pressure and the vapour is condensed with cold deep seawater.
  • The LTTD technology does not require any chemical pre and post-treatment of seawater and thus the pollution problems are minimal and suitable for island territories.
  • This technique works on the principle that water in the ocean 1,000 or 2,000 feet below is about 4º C to 8º C colder than surface water. So, salty surface water is collected in a tank and subject to high pressure (via an external power source). 
  • The pressured water vapourises and is trapped in tubes or a chamber. Cold water plumbed from the ocean depths is passed over these tubes and the vapour condenses into fresh water and the resulting salt is diverted away.
  • Currently, the desalination plants, each of which provides at least 100,000 litres of potable water every day, are powered by diesel generator sets — there being no other source of power in the islands.


Q1) What is Salinization?

Salinization is an accumulation of salts in the soil and on the surface of the soil. Salts enter the soil through irrigation; they originate either from geological layers, from groundwater or from man-made influences, such as fertilizers.

Source: National Institute of Ocean Technology to set up a green, self-powered desalination plant in Lakshadweep