a clean water breakthrough for MIT

 

A suitcase-sized device that requires less power to operate than a cell phone charger and costs around $50 to buy online. This is the latest water desalination breakthrough by a team of researchers at MIT. Announced in a press release yesterday, the portable desalination unit, weighing less than 10 kg, can remove particles and salts to generate clean, clear drinking water without the need for filters or high-pressure pumps.

 

After tests in the lab, two of the researchers Junghyo Yoon and Hyukjin J. Kwon took the device to Carson Beach in Boston to see how it would work out on the field. In about half an hour, the device generated a cupful of clear, drinkable water, which even exceeded the World Health Organization quality guidelines. 

 

‘It was successful even in its first run, which was quite exciting and surprising. But I think the main reason we were successful is the accumulation of all these little advances that we made along the way,’ comments senior author of the paper Jongyoon Han. 

 

Han continues, ‘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.’

MIT researchers build portable desalination unit that generates clean water at the push of a button
the user-friendly unit is suitcase sized

image by M. Scott Brauer (main video courtesy of J-WAFS at MIT)

 

 

How does it work?

 

Yoon explains that commercially available portable desalination units typically require high-pressure pumps to push water through filters, which are very difficult to miniaturize without compromising the energy-efficiency of the device.

 

Instead, the team’s portable unit uses a two part process of ion concentration polarization (ICP) followed by electrodialysis. Pioneered by Han’s group over 10 years ago, the ICP process removes both dissolved and suspended solids by use of an electrical field, which repels positively or negatively charged particles such as salt molecules, bacteria, and viruses. Clean water then passes through. However, ICP doesn’t get rid of all the salts floating in the middle of the channel, so the researchers incorporated electrodialysis to remove remaining salt ions.

 

‘While it is true that some charged particles could be captured on the ion exchange membrane, if they get trapped, we just reverse the polarity of the electric field and the charged particles can be easily removed,’ adds Yoon.

MIT researchers build portable desalination unit that generates clean water at the push of a button
the setup includes a two-stage ion concentration polarization (ICP) process

image by M. Scott Brauer

MIT researchers build portable desalination unit that generates clean water at the push of a button
the device can be powered by a small, portable solar panel

 

 

The final process boasts minimal energy usage and it’s self-cleaning, reducing long-term maintenance requirements. The device can also be also be powered by a small, portable solar panel. 

 

Designed for ‘nonexperts’, users need to push just one button to launch the process and a notification lets users know once the water is drinkable. The researchers also created a smartphone app that can control the unit wirelessly and report real-time data on power consumption and water salinity.

 

The team says the unit could be deployed in remote and severely resource-limited areas, such as communities on small islands or aboard seafaring cargo ships. It could also be used to aid refugees fleeing natural disasters or by soldiers carrying out long-term military operations.

MIT researchers build portable desalination unit that generates clean water at the push of a button
the portable device does not require any replacement filters

image by M. Scott Brauer

 

 

The researchers are currently working to scale up production, make the device more user-friendly, mprove its energy efficiency, and explore the use of low-cost materials.

 

‘Right now, we are pushing our research to scale up that production rate,’ comments Yoon.

 

‘This is definitely an exciting project, and I am proud of the progress we have made so far, but there is still a lot of work to do,’ adds Han. ‘Another limitation is the use of expensive materials. It would be interesting to see similar systems with low-cost materials in place.’

 

The research paper was authored by Junghyo Yoon, Hyukjin J. Kwon, SungKu Kang, Eric Brack, and Jongyoon Han, and you can find it here.

MIT researchers build portable desalination unit that generates clean water at the push of a button
senior author Jongyoon Han, right, pictured with Junghyo Yoon, seated

image by M. Scott Brauer