Automation/Desalination Fresh Water from the Sea – Automating a World–Scale Desalination Plant

| Author/ Editor: Indira Rao / Dominik Stephan

Water, water, everywhere - Nor any drop to drink: The Nemmeli sea water desalination plant in Tamilnadu uses reverse osmosis membranes to process sea water into drinkable water. It is also the first desalination plant to use electric actuators in redundant line topology for the automation of valves. Here’s a look at how highend technology was combined to build India’s largest seawater desalination plant...

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The new desalination plant will improve water supply at Chennai
The new desalination plant will improve water supply at Chennai
(Picture: VA Tech Wabag)

The Nemmeli sea water plant, with the capacity to treat 100 MLD sea water a day, is the first and largest desalination plant in India on Engineering, Procurement & Construction (EPC) basis meant for 100 per cent potable use. The project has been executed by the water treatment company, VA Tech Wabag in partnership with IDE Technologies (Wabag - IDE consortium) for the Chennai Metropolitan Water Supply and Sewerage Board (Chennai Metrowater).

Auma India was the technology provider for automating flow control valves throughout the desalination plant. The plant is constructed at a cost of `1033 crore on a design, build, operate basis and is spread across 81,000 sq mt of land. It uses reverse osmosis membranes to treat the sea water into potable water, to be supplied to Southern Chennai.

Owing to repeated failure of the monsoons, increasing urbanization and population, there is shortage of water supply in several areas across the Tamilnadu state. “With a view to overcome these challenges, desalination of sea water is considered as the best option considering the fact that we as a country are blessed with long coastlines,” said Sr Manager - E&I (Construction), VA Tech Wabag, K Manickam.

An EPC Contractof World–Scale Dimensions

Wabag was entrusted with the total responsibility of building this plant on EPC basis. It was a large and complex project involving procurement of specialized process equipment from various countries across the globe such as: RO membranes from Hydranautics, Japan; intake screens from Johnson Screens, Australia; UF membranes from NORIT, Netherlands; high pressure pumps from flow serve, Spain; disc filters from Arkal, Israel; super duplex pipes and fittings from H-butting, Germany and Tubacex, Spain etc.

Agreeing and talking about the process in detail, Manickam explained, “The piping materials used are exotic in nature and are not readily available and hence it had to be planned and procured well in advance.

"The precise operation of these motorized actuator valves plays a crucial role in the successful operation of the plant as it is wholly automated“ K Manickam, Sr Manager - E&I (Construction), VA Tech Wabag
(Picture: VA Tech Wabag)

Moreover, the fabrication of these piping materials had to be done under controlled conditions. The whole planning for the plant was meticulous which enabled us to commission the plant in record time without any hindrance. Even the critical work of intake and outfall under water pipeline laying work was successfully done at one go despite the adverse weather conditions and rough sea conditions in the Bay of Bengal.”

Precise Water Flow is the Key to Efficient Desalination

For efficient operation of the plant, precise water flow control is required at each stage, starting from intake till the post-treatment system. This calls for speedy communication between each system for maximum plant availability.

Therefore, electric actuators enabled with latest technologies were required to operate valves to control the flow of water throughout the plant. The electric actuators in redundant line topology for the automation of valves were supplied by Auma India.

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