Q. With reference to Low-temperature thermal desalination(LTTD), consider the following statements;
1.The technique uses cold water from the ocean depths to produce fresh water from vapour.
2.The LTTD technology requires chemical pre- and post-treatment of seawater..
Which of the statements given above is/are correct?
Answer: A
Notes:
Statement 1 is correct: 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).
This 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.
Statement 2 is incorrect: 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.
Source: PIB
