A book with pages that can be torn out to filter murky water and make it drinkable, has proved effective in field trials conducted at 25 contaminated water resources in South Africa, Ghana and Bangladesh.
In field tests, the book’s pages, which are treated with nanoparticles of silver or copper, managed to remove 99 percent of bacteria from the polluted water. Researchers said that while tiny amounts of silver or copper leached into the filtered water, these were well below safety limits and the purity level of the filtered water was similar to US tap water.
Dr. Teri Dankovich, a postdoctoral researcher at Carnegie Mellon University in Pittsburgh, who developed and tested the technology for the book over several years, said that the book was mainly directed towards communities in developing countries.
Over 780 million people around the world do not have access to clean drinking water, most of them living in the developing world. Each day, an estimated, 4,100 children under the age of 5 die from diarrhea, again mainly in poor countries. Around 45 percent of diarrhea, which kills around 1.5 million people globally, could be prevented by improving the quality of drinking water.
Dr. Dankovich added, "All 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 and other sources, and out comes clean water - and dead bacteria as well."
Explaining the technology involved, Dr. Dankovich said, "Ions that come off the surface of the silver or copper nanoparticles are absorbed by the microbes, killing them.” She added that based on her tests, one page can clean up to 100 liters of water and a book could filter one person's water supply for four years. She further clarified that the book contained printed information, in both English and the regional language, on why water should be filtered.
Following successful laboratory tests, Dr. Dankovich worked with social development agencies such as Water is Life and International Development Enterprises (iDE), over a period of two years to field-test the product in Africa and Asia.
She said that in these trials, the bacteria count in the water samples plummeted by well over 99 percent on average - and in most samples, it dropped to zero. "Greater than 90 percent of the samples had basically no viable bacteria in them, after we filtered the water through the paper," Dr. Dankovich said.
Dr. Dankovich and her colleagues are now hoping to step up production of the paper, which she and her students currently make by hand, and move on to trials in which local residents use the filters themselves.