Converting salt water into drinkable water would solve a lot of problems. Many poorer communities have fine access to the ocean, but almost no access to freshwater, and building infrastructure to provide that access is no easy feat.
As a result, research into desalination devices is at an all-time high, with the knowledge that a portable, cheap device could change the world – except, doing so is extremely difficult. Desalination requires energy, often large surface areas, and the waste product (brine) is a salty slurry that can cause damage to ocean ecosystems.
Now, researchers from the Department of Electrical Engineering and Computer Science, Massachusetts, have created a desalination device the size of a briefcase capable of creating clean drinking water from salty or brackish water, breaking through one of the largest barriers preventing desalination from reaching those that need it most.
The device is outlined in a paper published in Sustainable Systems.
Portable desalination devices would be the ideal solution to provide access to fresh water in extremely rural areas or those that are hit by natural disasters. However, current solutions rely on high-pressure pumps that are not suited to such scenarios.
To create a deployable and portable solution, the researchers looked to electrodialysis, a process where charged membranes separate ions from water, that has shown promise in desalination. Alongside the proven results, electrodialysis has seen energy efficiency improvements over the past years, making it a more viable option for a portable desalination device.
However, electrodialysis is not able to remove any solids in the liquid, which is rather important in creating drinking water. To circumvent this, the researchers also deployed an ion concentration polarization (ICP) system, allowing the device to remove solids and bacteria from the water too.
Through the use of both systems, seawater entered one side, and the product was crystal-clear, drinkable water which met the WHO guidelines for drinking water.
“It was successful even in its first run, which was quite exciting and surprising. But I think the main reason we were successful is the accumulation of all these little advances that we made along the way,” senior author Jongyoon Han said in a statement.
When they packaged the entire system into a briefcase-sized box powered by batteries and controlled by a smartphone, the finished product was a desalination device of impressive size and efficiency.
Furthermore, the device uses the brine by-product as a rinsing solution for the electrodes, and the waste product produces is almost the same salinity as the input water, drastically reducing the ecological impact of the device.
Work still needs to be done as the overall cost of producing drinking water is higher than larger desalination plants, but the device is an impressive option for use in areas where these plants are not an option.