Why in news?
Researchers at the Indian Institute of Science (IISc) announced a low‑cost desalination technique that uses a fabric‑lined siphon to turn seawater into drinking water. The innovation attracted attention for its potential to provide safe water in coastal areas without the high energy demands of conventional desalination plants.
How does the system work?
- Siphon principle: A curved metal tube lined with a capillary fabric draws seawater from a reservoir through capillary action. Once the siphon is primed, water flows upward and then down the other side.
- Thin‑film evaporation: Water trickles down the inner surface of the siphon as a very thin film. Solar heat or waste heat causes the film to evaporate quickly. Because the film is only a few millimetres thick, salt crystals do not form easily, avoiding scaling.
- Condensation chamber: A cool metal surface positioned close to the evaporating film condenses the vapour into freshwater droplets, which are collected.
Advantages over conventional methods
- High yield: The prototype produces more than six litres of potable water per square metre per hour, far exceeding traditional solar stills.
- Low energy input: The system harnesses solar energy or low‑grade waste heat and requires no electricity for pumping water.
- Minimal brine discharge: Because salt precipitates are largely avoided and remain in the brine, there is little concentrated brine to dispose of.
- Cost‑effective materials: The device uses inexpensive metals and fabrics, making it suitable for rural or remote coastal communities.
Limitations and future prospects
While promising, the system has yet to be tested on a large scale. Long‑term durability of the fabric and the system’s ability to handle fluctuating sea conditions remain uncertain. Scaling up will require engineering robust modular units and ensuring that condensed water meets drinking‑water standards. If these challenges are addressed, siphon‑powered desalination could complement other sustainable water solutions.