Introduction: Researchers at the Massachusetts Institute of Technology (MIT) have developed a portable desalination device that does not require any filters and pump pressures. Aquatech Online examines how the device works and its potential applications.
10-year desalination tour
Researchers at the Massachusetts Institute of Technology (MIT) have developed a portable desalination device that does not require any filters or pump pressures.
Weighing less than 10 kg, the unit can be placed in a suitcase, which can remove suspended solids and salts from seawater, and can produce drinkable fresh water with the help of mobile phone charger.
Jongyoon Han, a member of the Research Laboratory of Electronics (RLE), professor of electrical engineering/computer science and bioengineering, and senior researcher, said: "This is indeed the culmination of my team's 10-year research process."
"We've been working on physics behind the independent desalination process for many years, but putting all the research results in a small box and building a desalination device was a truly meaningful and valuable experience for me."
In contrast to other portable filtration desalination units like this, this non-filtration unit uses electricity to remove suspended solids and salts from seawater.
This is indeed the culmination of my group's 10-year research process.
This unit does not require filter replacement and does not require long-term maintenance.
Prior to this, MIT announced that Bloom Alert received the University's Water Innovation Award for its coastal desalination analysis platform.
No filter? No need to pump pressure?
The unit does not require a filter or pump pressure, but instead utilizes ion concentration differential polarization (ICP) to desalinate seawater.
The ICP process applies an electric field to the film placed on and under the water flow channel. When positively or negatively charged particles, including salt molecules, bacteria, and viruses, flow through, membranes repel them.
Eventually, charged particles are collected into a second stream of water for discharge. After the dissolved and suspended solids are removed, the water channel is clean, applicable water.
However, the research team ran into a conundrum, finding that ICP doesn't always remove all the salts floating in the water channel.
The researchers tried to introduce a second method to solve this problem, namely, electrodialysis to remove the remaining salt isolates.
Machine learning is used to find the best combination of ICP and electrodialysis. The result? In a two-stage ICP process, water flows through six modules in the first phase, then through three modules in the second phase, followed by an electrodialysis process.
This not only reduces energy consumption, but also ensures that the process remains self-cleaning. Junghyo Yoon said: "Although some charged particles can indeed be trapped on the ion exchange membrane, we can easily remove charged particles by reversing the polarity of the electric field."
The unit can reduce the amount of suspended solids by at least 10 times, producing drinkable fresh water at a rate of 0.3 L/hr, with only 20 W of electricity to be digested per L of freshwater production.
Once the process was designed, the team was able to shrink and stack the ICP and electrodialysis modules to improve energy efficiency and make them fit in a portable device.
A game-changing tool
The unit is also designed with non-specialists in mind and features an automatic desalination and purification unit that can be activated at the push of a button.
The team has also developed a smartphone app that can wirelessly control the device and report real-time data on electricity consumption and effluent salinity.
The suitcase-sized device automatically produces drinking water that exceeds World Health Organization (WHO) quality standards, MIT said. In addition, the unit can be powered by a $50 solar panel, which can be purchased online.
It's definitely an exciting project and I'm proud of the progress we've made so far, but there's still a lot of work to be done.
The device can be deployed in remote and resource-constrained areas, such as small islands, communities, or on seafaring cargo ships. It can also be used to assist refugees fleeing natural disasters or to carry out long-term operations for the military.
The device is still under development, and the research team hopes to further develop the technology to make it more energy efficient and easier to use. "It's definitely an exciting project and I'm proud of the progress we've made so far, but there's still a lot of work to be done," Han said.