This story is from November 8, 2018

Geography, resources aid easy desalination

Geography, resources aid easy desalination
KAVARATTI: Even as many areas in Kochi grapple with water scarcity, the islands of Lakshadweep have adopted a novel method to desalinate seawater and make it potable. Three desalination plants set up at Minicoy, Agatti and Kavaratti provide drinking water to islanders by using natural resources.
The plant uses the warm sea water on the surface and cold water from the sea’s depth for purification.
“Around the islands, the sea suddenly becomes deep soon after the shore as opposed to the mainland, where the depth of the sea increases gradually. This helps us get cold deep-sea water very close to the shore,” said Farooq, an operator at the desalination plant.
Warm water (30 degrees Celsius) is pumped into the desalination tank and vaporized drastically by decreasing the pressure inside the tank using vacuum pumps. On an average 100 litres of water is pumped into the tank per second and around a litre is converted into vapour. This vapour then reaches the surface of a copper tube coil through which cold water from the deep sea is pumped in. The vapour condenses outside the coils and is pumped out as fresh water.
“There will be shortage of minerals in the water that we produce and it is not ideal for children. However, most of us use this water for drinking purposes. Groundwater is also consumed by many in the island,” said Farooq.
Officials say that they produce over 1 lakh litres of fresh water every day and the expenditure is as low as 25 paise/litre. A fourth plant – which would be self-sufficient as it would produce the electricity needed for its functioning – is on the anvil.
At present, diesel is used to generate electricity from the plant with four main pumps. “We need to run two pumps each to pump in cold and warm water into the plant. Cold water is pumped in from a depth of 350m and warm water from the surface. Vacuum pump is used to bring the pressure inside the plant to as low as 25 millibar. The last pump is used to pump out the fresh water for consumption. The latest pump will generate electricity from the plant itself to run the pumps,” he said.
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About the Author
Disney Tom

Disney Tom is a senior correspondent with The Times of India in Kochi. He writes on a range of issues including crime, courts, religion, and culture. He joined The Times of India in 2015 through campus placement from the Asian College of Journalism, Chennai. He likes to travel and write about people and places.

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