New desalination technique pushes salt to one side with shock waves

As access to clean water continues to be an issue throughout the developing world, there's an increased demand for easier ways to turn contaminated and salty water into something you can drink. Researchers at MIT may have found a solution using a method they are calling shock electrodialysis. It uses electric shock waves to separate contaminated or salty water into two separate streams, with a natural barrier between each one.

The method developed at MIT is unlike most traditional desalination systems that either use some type of membrane less filter that can become clogged over time, or boiling methods that require extensive amounts of energy to produce clean water.

The MIT process sends water through an inexpensive porous material made of tiny glass particles, and across membranes or electrodes sandwiched on each side. As electricity is applied to the system, the salty water divides into zones of depleted or enriched salt concentration. Increasing the current generates a shock wave between the two zones, effectively adding a physical barrier that creates a flow of fresh water on one side and salty or contaminated water on the other.

Researchers involved in developing the process said that the system should be relatively easy to scale up for desalination or decontamination, but that it would not be immediately competitive with current reverse osmosis methods used for large-scale seawater desalination.

They added, however, that there are a number of initial applications for their shock electrodialysis method including decontaminating waste water generated by hydraulic fracturing, or fracking, and creating clean water in remote locations or in emergencies where access to fresh water could be disrupted by natural disasters. The next step is to create a larger system for practical testing.

Earlier this fall, researchers at Alexandria University announced an entirely different method of separation called pervaporization. The commercial viability of that method has also yet to be proven.

Source: MIT