MIT researchers build ground-breaking ‘desal’ unit that makes salt water drinkable

MIT researchers build ground-breaking 'desal' unit that makes salt water drinkable

Water is collected from the desalination system that runs on solar energy. Photo: USAID

(SCMP)Β The American engineers who travelled to rural India two years ago believed they were going to help poor villagers get rid of microbes in their drinking water. But soon after their arrival, they began hearing about a different problem: salt.

“People kept talking about the salt in the water,” recalled Natasha Wright, a doctoral candidate who was part of the team from Massachusetts Institute of Technology that made the journey in 2013. “The groundwater beneath the villages was brackish.”

Those complaints inspired new technology that could some day supply water to thirsty villages and drought-stricken farms in other parts of the world.

Solar panels supply electricity to the small desalination system that can supply water to drought-stricken rural areas. Photo: USAID

The MIT team developed a solar-powered water desalination system that uses the sun’s energy to turn brackish liquid into contaminant-free water safe for drinking and for crops.

While there are dozens of different desalination systems in use around the world, MIT’s is uniquely designed to be small, relatively cheap and 100 per cent solar-powered, making it suitable for remote areas where the electricity supply is unreliable or non-existent, Wright said.

The panel of judges last month deemed the machine’s potential so impressive that they gave the inventors the US$140,000 “Desal Prize”, an award sponsored by Securing Water for Food, a joint project of the US Agency for International Development and the governments of Sweden and the Netherlands. Some 68 engineering teams from 29 countries competed in the contest, hosted by the Interior Department’s Bureau of Reclamation.

Wright said she and fellow engineers from MIT’s Global Engineering and Research Laboratory became aware the extent of saltwater intrusion in northern and central Indian aquifers during visits to investigate solutions for widespread water contamination in India.

“People complained about the salty taste [of their water] and the salt ruined their cooking pots,” Wright said.

Illustration: Dr. Amy Bilton

Traditional desalination systems are expensive and require substantial amounts of electricity, making them impractical for India’s remote farming communities. Instead, the researchers designed a system that removes salt through a process called electrodialysis, using a series of electrodes and membranes.

They added solar panels and batteries to run the pumps and charge the electrodes. Then, in a final step, they installed ultraviolet light arrays to kill any microbes remaining in the water.

The finished prototype is small enough to fit in a tractor-trailer and includes photovoltaic cells to supply the electricity. The system, when fully operational, can supply the basic water needs of a village of between 2,000 and 5,000 people, MIT officials said.

Although the prototype was more expensive, Wright said the team hopes to lower the costs of a village-sized unit to about US$11,000.

Source:Β South China Morning Post

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