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article imageA new method of removing radioactive contaminants from wastewater

By Karen Graham     Dec 23, 2019 in Technology
Nuclear power plants use large volumes of water for cooling the reactors, which becomes contaminated with radioactive isotopes that require special long-term disposal. Researchers at MIT have come up with a way to decontaminate the wastewater.
The new method of decontaminating wastewater - developed at the Massachusetts Institute of Technology (MIT) would greatly reduce the amount of contaminated water that needs to be disposed of, concentrating the contaminants and allowing the cleaned water to be recycled through the plant's cooling system.
The proposed system is described in the journal Environmental Science and Technology, in a paper by graduate student Mohammad Alkhadra, professor of chemical engineering Martin Bazant, and three others.
The proposed system is safe, economical and scalable. It does not interfere with the operation of a reactor nor does it require expensive water replacement operations. To do this, the team, led by Alkhadra, has been working on a technology called shock electrodialysis.
The shock electrodialysis process
Shock electrodialysis was originally developed by Bazant about four years ago and was intended to be an efficient way of separating salt from sea or brackish water by literally shocking the salt from the water,
Basically, the system uses an electrically driven shockwave within a stream of flowing water that literally pushes salty water to one side of the flow and freshwater to the other. Now, the researchers are focusing on a more specific application, writes Phys.org, that is designed to "improve the economics and environmental impact of working nuclear power plants."
Diagram illustrates the process  in which contaminated water enters from the left  and is subjected ...
Diagram illustrates the process, in which contaminated water enters from the left, and is subjected to an ionic shockwave (depicted by dashed purple lines) that concentrates radionuclides of cesium and cobalt on one side (darker area at top) from purified water (light-colored lower area).
MIT research team
In the new method, a deionization shockwave in a tube of water is used to push electrically charged ions into a charged porous material that acts as the tube's lining. In other words, if the ions consist of the desired element for disposal, they can be selectively filtered out of the coolant water flow, according to New Atlas.
Bazant says. "It's a single device that can perform a whole range of separations for any specific application." The research team is also looking at removing lead from drinking water.
So far, the MIT team has been able to remove 99.5 percent of cobalt and cesium radionuclides in the water while retaining about 43 percent of the cleaned water for reuse.
MIT says that the technique can be used for handling contaminated water in disaster situations like the crippled Fukushima Daichi power plant in Japan. Bazant says that such large-scale decontamination systems based on this method might be possible "within a few years."
More about radioactive contaminants, Wastewater, radionuclides, shock electrodialysis, Nuclear power
 
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