Success of Low Temperature Thermal Desalination Technology
The Ministry of Earth Sciences (MoES) had launched a program for development of Low Temperature Thermal Desalination (LTTD) technology for conversion of seawater into potable water, suitable for installation in the island territories and near the coastal Power Plants. The National Institute of Ocean Technology (NIOT) an autonomous body of the Ministry of Earth Sciences has been responsible for design, develop, demonstrate and commission the LTTD plants in selected coastal locations. Till date, 4 LTTD plants have been successfully commissioned in the country, one each at Kavaratti, Minicoy, Agatti of Lakshadweep and one at Northern Chennai Thermal Power Station (NCTPS), Chennai. Out of these four plants, the Minicoy and Agatti plants were established in April 2011 and July 2011, respectively. The capacity of each of these LTTD plants is 1 lakh liter per day of potable water. The water is used locally. Besides, the ministry is working to set up 6 more plants being funded by the Lakshadweep Administration, one each in the islands of Lakshadweep viz., Amini, Chetlet, Kadamath, Kalpeni, Kiltan and Andrott plants.
The Reverse Osmosis, a membrane process, is globally accepted technology suitable for desalination of saline water, which is quite different from LTTD technology developed by the ministry. The LTTD is a process under which the warm surface sea water is flash evaporated at low pressure and the vapour is condensed with cold deep sea water. 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. Since no effluent treatment is required, it gives less operational maintenance problems compared to other desalination processes. The LTTD technology is completely indigenous, robust and environment friendly. The cost per liter of desalination would depend on the technology used and cost of electricity which varies from place to place. According to the cost estimates made recently by an independent agency for LTTD technology, the operational costs per litre of bottled quality fresh water currently works to be 19 paise. Since the LTTD technology is not matured for coastal regions of mainland India, except in thermal power plants located very near to the coast, so far no attempt has been made to introduce such plants in Andhra Pradesh. The coastal areas would require offshore plant with larger capacity, which are yet to develop.
This information was given by the Minister of State for Science and Technology and Earth Scviences Dr Ashwani Kumar in a written reply to a question by Shri R C Singh in Rajya Sabha today.
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KP