MIT creates portable device that makes seawater drinkable

Researchers at the Massachusetts Institute of Technology (MIT) have developed a portable device that can desalinate and remove particles from seawater, making it safe to drink.

Weighing less than 10 kg, the device is the size of a handbag and requires less energy to operate than it takes to charge a mobile phone battery. In addition, its operation is very simple: just press a button.

Unlike other portable desalination devices, which require periodic filter replacement, the device created by MIT researchers uses electrical energy to remove particles from the water. The result is drinking water that even exceeds the quality standards set by the World Health Organization (WHO).

According to the developers, the need for filter replacement significantly reduces the long-term maintenance costs. This may favor the deployment of the device in remote areas with limited resources, such as on small islands or on board sea cargo ships.

The portable water machine can be useful in extreme situations

According to one of the project’s authors, Jongyoon Han, professor of electrical engineering and computer science, biological engineering and a member of MIT’s Research Electronics Laboratory (RLE), the device could also be used to help victims of natural disasters or soldiers on long-term missions.

“It is the culmination of a 10-year journey that my group and I have traveled. We have been working for years with the physics behind individual desalination processes, but putting all these advances in a box, building a system and demonstrating it in the ocean has been a truly meaningful and rewarding experience for me, ”he said. .

MIT creates a portable device that makes water
Junghyo Yoon, one of the creators of the device, drinks the freshly purified seawater. Image: MIT

Junghyo Yoon, co-creator of the product, explains that portable desalination devices available on the market today typically require high-pressure pumps to drive water through the filters. Moreover, according to Yoon, they are very difficult to reduce in size without compromising on their energy efficiency.

In contrast, the desalination unit they offer is based on a technique called ion concentration polarization (ICP). Instead of filtering water, the ICP process uses an electric field on membranes above and below a water channel.

As a result, the membranes repel salt molecules, bacteria, viruses, and other positively or negatively charged particles as they pass. The charged particles are led into another stream of water, which is discharged.

The use of dissolved and suspended solids allows the passage of pure water through the canal. ICP requires only a low pressure pump and uses less energy than other techniques.

However, the ICP does not always remove all salts that pass through the center of the channel. For this reason, the researchers combined another process, called electrodialysis, to remove the remaining salts.

To find the perfect combination of ICP and electrodialysis modules, machine learning was used, the ideal setup of which includes a two-step ICP process, where the water flows through six modules in the first step and then to through three in the second, followed by a unique electrodialysis process.

This reduces energy consumption and ensures that the process remains self-cleaning. “While it is true that some charged particles can get trapped in the ion exchange membrane if they get stuck, we just reverse the polarity of the electric field and the charged particles can be easily removed,” Yoon said.

The seawater purifier is now for sale

Through a smartphone app, also developed by the research team, the user can control the device wirelessly and report real-time information on energy consumption and water salinity.

To test the function of the device, several experiments were performed in the laboratory with water with different levels of salinity and turbidity. Then came the test phase On-sitewhen the researchers traveled to Carson Beach, a beach south of Boston.

There they placed the box in the sand and dropped the feeding tube into the water. In about half an hour, the device filled a plastic cup with drinking water. “It was a success even in its first race, which was quite exciting and surprising. But I think the main reason for our success is the accumulation of all these little leaps we have taken along the way,” he said.

In addition to exceeding WHO quality guidelines, the resulting water is reduced in suspended solids by at least a factor of 10. The prototype produces drinking water at a rate of 0.3 liters per hour and requires only 20 watts of energy per liter.

The equipment is already available for sale on the Internet for about 50 US $ (equivalent to about 254 R $). The tool has a small portable solar panel, which is also capable of powering the machine.

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