World’s First LTTD Plant Developed By Indian Scientists
“The simplicity of the LTTD process also enables to control the quality of product water in order to provide potable drinking water.”
Scientists at the National Institute of Ocean Technology (NIOT), Chennai have developed world’s first low temperature thermal desalination plant, which could address drinking water problems in India’s ocean island territories and even offshore urban centres along the coastline.
Low temperature thermal desalination (LTTD) is one process that uses the availability of a temperature gradient between two water bodies or flows to evaporate the warmer seawater at low pressures and condense the resultant vapour with the colder seawater to obtain fresh water.
“The 12-13oC cold water available at about 400m depth within 600m from the island is used along with the surface water at about 28oC to produce potable water in the Lakshadweep Islands,” Dr Ramana Murthy, Scientist at NIOT told Indian Science Journal.
“One of the advantages of the process is that it can be implemented even with a low temperature gradient of about 8¬-10oC between two water bodies, with no additional requirement of heating/cooling,” Dr Atmanand said.
Even though flash distillation is a commonly used desalination process worldwide and especially in Middle East, none of the established plants work with the temperature gradient as low as 8oC as is possible in the LTTD process.
Installation of LTTD projects is not without any technical challenges. Site-specific design and installation of 950 m long pipeline to draw cold water from 350 metre depth and marine structure to draw cold/warm water and to support the pipeline is a major challenge.
Dr Atmanand said, LTTD technology was also demonstrated using waste heat generated from the North Chennai Power Plant to produce fresh water. The demonstration plant has a capacity of one lakh litres per day. NIOT has also commissioned a barge-mounted plant of 1 million litres per day off Chennai, which once scaled up can address drinking water shortage in the southern metropolis.