New York: Leveraging on the bacteria-killing properties of silver and inexpensive copper, a US researchers has developed a low cost, simple and easily transportable paper-based method to purify drinking water.
Called "The Drinkable Book", and each page of the device is impregnated with bacteria-killing metal nanoparticles.
Printed on each page is information on water safety both in English and the language spoken by those living where the filter is to be used.
Each page can be removed from the book and slid into a special holding device in which water is poured through and filtered.
According to Theresa Dankovich, postdoctoral researcher at Carnegie Mellon University who developed the "Drinkable Book", a page can clean up to 100 litere of drinking water and the entire book can filter one person's water needs for four years.
Bacteria killer
Although silver and similar metals have been known for centuries to have the ability to kill bacteria, no one had put them into paper to purify drinking water, Dankovich noted.
Field investigations of the water purification application were conducted in Limpopo, South Africa, as well as northern Ghana, Haiti and Kenya.
"In Africa, we wanted to see if the filters would work on 'real water,' not water purposely contaminated in the lab," she said.
"One day, while we were filtering lightly contaminated water from an irrigation canal, nearby workers directed us to a ditch next to an elementary school, where raw sewage had been dumped. We found millions of bacteria; it was a challenging sample," Dankovich noted.
"But even with highly contaminated water sources like that one, we can achieve 99.9 percent purity with our silver- and copper-nanoparticle paper, bringing bacteria levels comparable to those of US drinking water," Dankovich said.
The technology of the water filter and results of recent field tests conducted in Africa and Bangladesh were presented at a meeting of the American Chemical Society (ACS).
Highlights
- Its pages that can be torn out to filter drinking water. Proven effective in its first field trials.
- It combines treated paper with printed information on how and why water should be filtered.
- Its pages contain nanoparticles of silver or copper -- effective bacteria killers in the water as it passes through.
- In trials at 25 contaminated water sources in South Africa, Ghana and Bangladesh, the paper successfully removed more than 99 per cent of bacteria.
- Resulting levels of contamination are similar to US tap water
- Tiny amounts of silver or copper also leeched into the water, but these were well below safety limits.
- The results were presented at the 250th national meeting of the American Chemical Society in Boston, US.
- Dr Teri Dankovich, a postdoctoral researcher at Carnegie Mellon University in Pittsburgh, developed and tested the technology for the book over several years, working at McGill University in Canada and then at the University of Virginia.
- Solution is aimed at communities in developing countries.
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you need to do is tear out a paper, put it in a simple filter holder and pour water into it from rivers, streams, wells etc and out comes clean water — and dead bacteria as well.
How it works
- The bugs absorb silver or copper ions — depending on the nanoparticles used — as they percolate through the page.
- Ions come off the surface of the nanoparticles, and those are absorbed by the microbes
- One page can clean up to 100 litres of water. A book could filter one person’s water supply for four years.
