Low-cost filter to provide safe water in emergency

McGill researchers have come up with a new and inexpensive way of filtering water using silver nanoparticles.
Disasters such as floods, tsunamis, and earthquakes often result in the spread of diseases like gastroenteritis, giardiasis and even cholera because of an immediate shortage of clean drinking water.

Now, researchers at McGill University have taken a key step towards making a cheap, portable, paper-based filter coated with silver nanoparticles to be used in these emergency settings.

"Silver has been used to clean water for a very long time. The Greeks and Romans kept their water in silver jugs," said Prof. Derek Gray, from McGill's Department of Chemistry.

But though silver is used to get rid of bacteria in a variety of settings, from bandages to antibacterial socks, no one has used it systematically to clean water before.

Gray's team, which included graduate student Theresa Dankovich, coated thick (0.5mm) hand-sized sheets of an absorbent porous paper with silver nanoparticles and then poured live bacteria through it.

The results were definitive. Even when the paper contains a small quantity of silver (5.9 mg of silver per dry gram of paper), the filter is able to kill nearly all the bacteria and produce water that meets the standards set by the American Environmental Protection Agency (EPA).

The filter is not envisaged as a routine water purification system, but as a way of providing rapid small-scale assistance in emergency settings.

The study was recently published in the Journal of Environmental Science and Technology.

--ANI