Sea water desalination brings relief to drought prone Tamil Nadu village

Narippaiyur, a village in Ramanathapuram District, a drought prone area situated in the South-East corner of Tamil Nadu will benefit from 20,000 litres per day of fresh water produced from sea water – thanks to the solar thermal Forward Osmosis (FO) sea water desalination system installed in the place.

The customized demand driven convergent water solution through FO will supply two litres of good quality drinking water per person per day for 10,000 people in the village, successfully overcoming a major drinking water shortage in the village. The FO system facilitates high recovery, low energy consumption, potential for resource recovery, especially in solutions of high osmotic pressure, less fouling of the membrane because of low pressure operation, easier and more effective cleaning of the membrane, longer membrane life and lower operating costs.

Tamil Nadu IIT Madras in collaboration with Empereal – KGDS Renewable Energy have successfully established and demonstrated this system to address prevalent and emerging water challenges in Mission Mode in the village.

Ramanathapuram District, situated in the South-East corner of Tamil Nadu, is severely affected by scarcity of potable water due to salinity, brackishness and also poor sources of ground water. The district of 423000 hectares has a long coastal line measuring about 265 kilometres accounting for nearly 1/4th of the total length of the coastal line of the state.

The Water Technology Initiative, Department of Science & Technology (DST) has supported this field based effort in the district through the consortium members led by Indian Institute of Technology Madras (IITM), KGiSL Institute of Technology (KITE), Empereal– KGDS Renewable Energy (P) and ICT Mumbai.

The sea water FO technology operates at near 2 bar pressure unlike sea water RO that operates at 50 bar pressure. It is versatile, has high energy efficiency and low operation and maintenance costs compared to other technologies.

The produced water will be supplied to the local people with the support of villagers and panchayat. This initiative of DST can pave way for scaling up the emerging technology in various coastal rural areas of the country to address drinking water shortage.

Making fresh water out of seawater usually requires huge amounts of energy. The most widespread process for desalination is called reverse osmosis, which works by flowing seawater over a membrane at high pressure to remove the minerals. The challange, therefore, has been to how to have this osmosis with lesser consumption of energy.

Reverse osmosis is used in many countries; in arid places like the Middle East, more than half of the fresh drinking water supplies come from desalination facilities. But to maintain the high level of pressure required for the process – up to 70 times atmospheric pressure – a desalination plant must employ large numbers of pumps and other equipment. And that uses a lot of energy. However, reverse osmosis is a complex process as one has to track many variables: water pressure, volume, salinity, recovery ratio, time and energy.

Viewed thus, the FO desalination system is a big development that will go a long way in augmenting the supply of the drinking water in the country.