CHEAP NEW WAY TO CLEAN WATER

by Ben Daviss

One person in ten around the world lacks ready access to clean water. Those people spend hours a day hauling water in buckets and pots from faraway sources.

Solar stills – usually a black-bottomed vessel covered by a clear dome that water vapor condenses on – can pull clean water from dirty, but one still usually yields only a trickle, barely enough for a small family’s minimum daily needs. 

But the problem with solar stills is that sunlight has to heat all the water inside before any will evaporate.

Now scientists at the University of Texas have found a way to speed up solar water-making. The group used hydrogels, which are networks of water-absorbing polymers. They combined a hydrogel that absorbs light with two that bind water molecules and made a sort of sponge, which floats on the water in a still.

Water molecules are absorbed into the sponge and bind tightly with the water-binding hydrogels. Because the water is so tightly bound to the hydrogels, it has no connections left to bind to other water molecules. Yet the sponge continues to absorb water from the cistern in the still. Because those new molecules can’t find anything to bind to, they evaporate much faster than they otherwise would.

The researchers report that their method puts out 12 times more water than commercially available solar stills do now. That means a solar still about three square feet in size could deliver about 30 liters of water a day – roughly eight gallons, or enough for cooking and basic hygiene for a small family.

TRENDPOST: Clean water is becoming scarce; some experts are predicting “water wars” in the years ahead. Entrepreneurs who can solve the scarcity of clean water will enter a wide-open market for low-cost technologies.