Indian scientists achieve success in converting sea water into drinking water

Indian scientists have accomplished noteworthy success in converting sea water into drinking water. Under a pilot project of the Earth Sciences Ministry, the Indian scientists have developed the Low Temperature Thermal Desalination technology to convert seawater into drinking water. This indigenously developed environment- friendly technology is suited for island territories and coastal areas.

So far, 4 plants have been commissioned in India, located at: Kavaratti, Minicoy and Agatti in Lakshadweep and at the Northern Chennai Thermal Power Station in Chennai. 6 more plants are to be installed in Lakshadweep. They will be located at Amini, Chetlet, Kadamath, Kalpeni, Kiltan and Andrott islands of the Union Territory.

Each plant has a capacity to produce 1,00,000 litre of potable water every day. The operational cost of producing one litre of drinking water from the saline water is 19 paise and efforts to further reduce the production cost are taking place.

What is Low-temperature thermal desalination (LTTD)?

Principle behind this technology:

Low-temperature thermal desalination (LTTD) is a desalination technique takes advantage of the fact that water boils at low pressures, even as low as ambient temperature.

The system uses vacuum pumps to create a low pressure, low-temperature environment in which water boils at a temperature gradient of 8 to 10 °C between two volumes of water. Cooling water is supplied from sea depths of as much as 600 metres (2,000 ft). This cold water is pumped through coils to condense the evaporated water vapour. The resulting condensate is purified water. The LTTD process may also take advantage of the temperature gradient available at power plants, where large quantities of warm waste water are discharged from the plant, reducing the energy input needed to create a temperature gradient.

The principle of LTTD is known for a long time, originally stemming from ocean thermal energy conversion research. LTTD was studied by India’s National Institute of Ocean Technology (NIOT) from 2004. Their first LTTD plant was opened in 2005 at Kavaratti in the Lakshadweep islands. The plant’s capacity is 100,000 litres/day, at a capital cost of INR 50 million (€922,000). The plant uses deep water at a temperature of 7 to 15 °C.

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