Researchers find way to filter water that uses 1,000 times less energy

4 May 2017

Image: Tik Duangdee/Shutterstock

A team led by a University of Limerick researcher has achieved a major breakthrough in water filtration that lets it use 1,000 times less energy than conventional methods.

With climate change expected to make vast tracts of land unsuitable for human habitation – whether that be through coastal flooding or drought – the need to find cheap and easy ways to filter water is now essential.

Last month, a team of researchers from the University of Manchester (UM) demonstrated a system that would use the wonder material graphene to sieve out salt in seawater, making it potable.

Now, a group of researchers – including the University of Limerick’s Dr Orest Shardt and Dr Sangwoo Shin from the University of Hawaii – have found a similar and novel way to filter water using CO2.

Currently, water filtration technologies, such as microfiltration or ultrafiltration, use porous membranes to remove suspended particles and solutes.

These processes trap and remove suspended particles, such as fine silt, by forcing the suspension through a porous material with gaps that are smaller than the particles.

However, energy must be wasted to overcome the friction of pushing the water through these small passages, making it expensive for industries to pump and maintain these filtration systems.

Publishing their findings in the journal Nature Communications, the researchers demonstrated their own method, which is an alternative, membraneless system that works by exposing the colloidal suspension (a materials-heavy solution) to CO2.

Now to make it affordable

The device is developed from a standard silicone polymer that is commonly used in microfluidics research and has similar traits to sealants used in people’s homes.

“While we have not yet analysed the capital and operating costs of a scaled-up process based on our device, the low pumping energy it requires – just 0.1pc that of conventional filtration methods – suggests that the process deserves further research,” said Shardt.

“What we need to do now is to study the effects of various compounds, such as salts and dissolved organic matter that are present in natural and industrial water, to understand what impact they will have on the process.”

This research was conducted last year by Shardt and Shin when they were post-doctoral researchers at Princeton University.

Updated, 10.06am, 5 May 2017: This article was amended for clarification.

Colm Gorey was a senior journalist with Silicon Republic