Novel membrane distillation technology for desalination unveiled

SINGAPORE: A group of researchers from Ngee Ann Polytechnic has created a sea water distillation system using a first—of—its—kind nanofibre—based membrane.

Called Distil, the system can produce up to more than 200 litres of desalinated water per hour or 5,000 litres per day.

Most membrane distillation systems work on the basis of water transfer, which may generate products that are not as pure.

But not these nanofibre—based membranes.

These "water—repelling" or what is scientifically known as hydrophobic membranes allow only pure water vapour to pass through.

The system even earned the team two patents — one for the novelty of the membrane, another for the highly—efficient process of its technology.

With two other core staff members Antony Prince and T S Shanmugasundarum, and supported by a group of students, the team feels that there is great potential for Distil.

Principal researcher Dr Gurdev Singh said: "Singapore like most countries globally are looking at water sources that they could tap on, to augment their existing water supply. The oceans offer huge potential as an area that could be tapped to generate water. Our system allows us to do just that — desalinate sea water but at a lower energy consumption of less than 1.5 kilowatts an hour per metre cube."

To be exact, it’s using almost half the energy to recover about twice the amount of pure water from sea water.

The system is able to recover 60 to 80 per cent of pure water from sea water, as compared to the recovery rate of between 30 and 50 per cent using conventional reverse osmosis systems.

Sea water will first enter the system, which is powered by solar energy.

Solid particles are filtered away while the sea water is being heated by solar thermal collectors.

Then it’s channelled through the membranes where only pure water vapour can pass through, and is condensed and collected.

Rather than being seen as a competitor, the system can complement existing reverse osmosis processes.

Director of the Environmental & Water Technology Centre of Innovation at Ngee Ann Polytechnic, Tam Li Phin, said: "This system can be used as a small scale for small communities. For example, in less developed countries, where there’s no power electricity to run treatment systems, we can use this to produce drinking water."

— CNA/ck