A portable device that turns seawater into drinking water, without using filters

Four billion people — almost two thirds of the world’s population — experience severe water scarcity for at least one month each year. Over two billion people live in countries where water supply is inadequate. Half of the world’s population could be living in areas facing water scarcity by as early as 2025. “There is a water crisis today. But the crisis is not about having too little water to satisfy our needs. It is a crisis of managing water so badly that billions of people – and the environment – suffer badly.”    World Water Vision Report.

Water scarcity limits access to safe water for drinking and for practising basic hygiene at home, in schools and in health-care facilities. When water is scarce, sewage systems can fail and the threat of contracting diseases like cholera surges. Scarce water also becomes more expensive.

Massachusetts Institute of Technology (MIT) researchers have developed a portable desalination unit, weighing less than 10 kg, that can remove particles and salts to generate drinking water. 

Small suitcase-sized device needs veryless power to operate than a cell phone charger, which can generate from solar panel easly. It can also be driven by a small, portable solar panel, Device can be purchased online in the price around $50 (about Rs 3,800 at current exchange rates), MIT said in a news release. It said the device automatically generates drinking water that exceeds World Health Organization (WHO) quality standards. The device runs with the push of one button.

Other small portable devices whcih are in market need more power and very strong filters but on the other hand newly developed device can operat on very minimum power, without filter. These properties make the device promenent among others.

“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,” says senior author Jongyoon Han, a professor of electrical engineering and computer science and of biological engineering, and a member of the Research Laboratory of Electronics (RLE).

HOW IT WORKS: The unit relies on a technique called ion concentration polarisation, which was pioneered by Han’s group more than 10 years ago, the release said. Rather than filtering water, the process applies an electrical field that causes positively or negatively charged particles — including salt molecules, bacteria, viruses — to be repelled as they flow past. The charged particles are funnelled into a second stream of water that is eventually discharged. The process removes solids, allowing clean water to pass through the channel.

Filterless technology

Normally such sort of avilabe devices need very strong electric water pump to puch the water through filter which hard to main maintain and price of water also increase due to energy usgae and filter explains Yoon.

But their device opted very advance technology named “ion concentration polarization” (icp) which orignally owned by Han,s Group10 years ago. Insted the use of filter in this technology electrical field is applied to foild the wats particaled from the water. Water iis flow inbetween postitive and negative charged and charged particles are funneled into a second stream of water that is eventually discharged.

“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,” Yoon explains.

“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,” Han says.

The researchers fit the technology into a portable device to further make the technology energy efficient. Most importantly, the team designed the device for non-experts with just one push of a button to launch an automatic desalination and purification process. The device will notify the user once the number of particles decreases to specific thresholds, which signals that the water is now drinkable.

“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,” Han says. since it does not remove all particles in the first part, the team incorporated a second process called electrodialysis to remove the remaining salt ions. They used machine learning to find the ideal combination of the ICP process and electrodialysis. “Right now, we are pushing our research to scale up that production rate,” Yoon says.