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New device makes desalination possible with the push of a button

A team of researchers led by the Massachusetts Institute of Technology (MIT) has recently developed a portable desalination unit, which weighs less than 10 kilograms and can remove salts and particles in order to generate clean water. This new technology is packaged into a user-friendly device that runs with the push of one button, and can generate drinking water at a rate of 0.3 liters per hour, requiring only 20 watts of power per liter.

Unlike other portable desalination units which require water to pass through several filters, this groundbreaking device utilizes electrical power to remove unwanted salts and other particles.

“This is really the culmination of a 10-year journey that I and my group have been on. We worked for years on the physics behind individual desalination processes, but pushing all those advances into a box, building a system, and demonstrating it in the ocean, that was a really meaningful and rewarding experience for me,” said study senior author Jongyoon Han, a professor of Electrical Engineering and Computer Science at MIT.

While commercially available portable desalination units usually require high-pressure pumps to push water through filters, this newly developed device relies on a technique called ion concentration polarization (ICP) that was pioneered by Professor Han’s team over 10 years ago. Instead of filtering the water, the ICP process applies an electric field to membranes placed below and above a channel of water, repelling positively or negatively charged particles, such as salt molecules, viruses, or bacteria, as they flow by. These particles are then funneled into another stream of water which is eventually discharged. 

Although the ICP process does not remove all the salts floating in the middle of the channel, incorporating a second process called electrodialysis can finally remove all the remaining salt ions. By using machine learning to find the ideal combination of ICP and electrodialysis modules, the scientists found that a two-stage ICP process with water flowing through six modules in the first stage and three additional ones in the second stage, followed by a single electrodialysis process is optimal for cleaning the water at a level that exceeds World Health Organization’s quality guidelines

This amazing device – which the researchers already field-tested at Boston’s Carson Beach – could be deployed in remote and resource-limited areas, such as small islands or seafaring cargo ships in order to clean seawater of salts, impurities, or pathogens. Moreover, it could also help refugees fleeing natural disasters or soldiers carrying long-term military operations have constant access to clean water.

A detailed description of the device is published in the journal Environmental Science & Technology.

By Andrei Ionescu, Staff Writer

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