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.
- 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.
- 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.
Differences between Forward Osmosis (FO) and Reverse Osmosis (RO)
- In reverse osmosis, water is forced through the membrane using hydraulic pressure to overcome the natural osmotic pressure. The higher the salinity of the feed solution, the more pressure is needed. This requires high-pressure pumps and vessels with significant quantities of energy as a result.
- Reverse osmosis also requires membranes that are suited for the specific task, such as brackish water membranes, seawater membranes, high-pressure or ultra-high-pressure membranes.
- Forward osmosis, on the other hand, uses natural osmotic pressure to induce the flow of water through the membrane by running a highly saline draw solution on the other side of the membrane. This means that the feed solution flows through the membrane at a relatively low pressure which eliminates the need for high-pressure hydraulics.
- The sea water FO technology operates at near 2 bar pressure unlike sea water RO that operates at 50 bar pressure.
- A well-known issue with reverse osmosis membranes is fouling and scaling, where organic and chemical residue, oxidants and scaling ions build up on the membrane surface.
- With forward osmosis, the low pressure of the feed solution makes the FO membrane less sensitive to fouling and scaling issues.
- Forward osmosis is versatile, has high energy efficiency and low operation and maintenance costs compared to other technologies.
