Around the world, there is more salty groundwater than fresh, drinkable groundwater. For example, 60 percent of India is underlain by salty water — and much of that area is not served by an electric grid that could run conventional reverse-osmosis desalination plants.

Now an analysis by MIT researchers shows that a different desalination technology called electrodialysis, powered by solar panels, could provide enough clean, palatable drinking water to supply the needs of a typical village.

By pairing village-scale electrodialysis systems — a bit smaller than the industrial-scale units typically produced today — with a simple set of solar panels and a battery system to store the produced energy, an economically viable and culturally acceptable system could double the area of India in which groundwater — which is inherently safer, in terms of pathogen loads, than surface water — could provide acceptable drinking water.

Electrodialysis works by passing a stream of water between two electrodes with opposite charges. Because the salt dissolved in water consists of positive and negative ions, the electrodes pull the ions out of the water, leaving fresher water at the center of the flow. A series of membranes separate the freshwater stream from increasingly salty ones.

The researcher plan to put together a working prototype for field evaluations in India in January.


Also: Learn about a System For Measuring Osmotic Transport Properties of a Membrane.