An Electric Shock to Flowing Water Makes it Potable



Clean and potable water can be obtained from effectively treated salty, brackish or contaminated water so that it can be safe to drink.  A “membraneless separation” of the salt ions and water molecules is in the offing!  An electrically-driven shockwave within a stream of flowing water had achieved it.

The process called “shockwave electrodialysis” was developed by a team of chemical engineers at MIT.  Water is allowed to flow through a porous material of tiny glass particles called a frit, sandwiched by electrodes.  When an electric current flows through the system, the  salty water divides into regions where the salt concentration is either depleted or enriched.  When the current is increased to a certain level, it generates a shockwave between these two zones.

The shockwave divides the streams, allowing the fresh and salty regions to be separated by a physical barrier at the center of the flow.  There are still membrane components involved, but, the water flows across these membranes, not through them.  It means, the membranes are less vulnerable to fouling from filtered material.  They are also saved from degradation due to water pressure, a common problem with conventional membrane-based reverse osmosis desalination processes.

The shockwave is applied to a running stream of water and so it is a continuous process and the porous medium used is also inexpensive.  So, the system should be relatively easy to scale up for high-volume desalination and purification applications.  In the lab it had been tested well. The next step would be to design a scaled-up system to use for practical testing.  It is possible to turn it for future commercial-scale versions of the system.

  1. The vast amounts of wastewater generated by hydraulic fracturing or fracking can be   recycled.  It is an affordable, practical method of dealing with this water.
  2. The system is also able to sterilize water by killing bacteria.
  3. It requires little infrastructure  and so, the technology can be developed into portable systems that can be deployed in emergency situations where water supplies are disrupted by storms, floods and earthquakes.
  4. This system offers an advantage over conventional filter membrane systems which rely on energy-intensive boiling processes.
  5. If successful at a commercial scale, it would offer safe, clean water to people in areas lacking sophisticated infrastructure.

Source: Engineering