New System Uses Electrical Shockwaves to Purify Water

The Innovation

Life as we know it exists because of water. Indeed, a majority of the human body is composed of water, so calling it "vital" is a bit of an understatement. We simply cannot do without it; however, despite this fact, less than 1% of freshwater is available for human consumption.

Consequently, the need for potable water is urgent, and the need will only increase an our population grows.

Researchers from MIT tried to tackle this problem by coming up with an innovative approach to desalination. Notably, their system does not rely on the separation of  ions or water molecules with filters, which can be clogged. It also doesn't involve boiling, which consumes large amounts of energy. Their process is referred to as “shock electrodialysis, and is described by the researchers as a form of “membraneless separation” of ions and particles.

Water flows through a porous material made of tiny glass particles called a "frit." The frit has membranes or electrodes sandwiching it on each side. With an electric current, the salty water divides. Thus, the salt concentration is either depleted or enriched, depending on which side you are looking at. When that current is increased to a certain point, it generates a shockwave between these two zones, dividing the streams and allowing the fresh and salty regions to be separated by a simple physical barrier at the center of the flow.

So see why we are in dire need of processes like these, check out the infogrpahic below.

Applications

This system not only removes salt, but also a wide variety of other contaminants. Thus, besides providing potable freshwater, another application would be cleaning wastewater, like what is generated by hydraulic fracturing (fracking). This contaminated water has traces of toxic ions, and shock electrodialysis would be practical and inexpensive way of decontaminating it. The electrical current involved may also sterilize the water.

Moreover, as the system requires little infrastructure, it may be used for portable systems in remote locations, or for emergencies where water supplies are disrupted by disaster situations. Now, the researchers are looking onto scaling up the system.