Imagine a book that has pages you can tear out and use to turn raw sewage into drinking water. Each page is implanted with silver or copper nanoparticles that kill bacteria when water passes through them. And each page is printed with a message in your local language: “The water in your village may contain deadly diseases. But each page of this book is a paper water filter that will make it safe to drink.”
That’s exactly what one postdoctoral researcher at Carnegie Mellon University says she’s created. She calls it the “drinkable book.”
“I originally starting working on it to help the environment — by using greener chemistry, and it’s evolved to have the noble goal of helping others,” Theresa Dankovich, who has been working on the product over the past several years, told The Washington Post in an e-mail.
The new water filtration system has been shown to eliminate 99 percent of bacteria in water during its first field trials at 25 contaminated water sources in South Africa, Ghana, Kenya, Haiti and Bangladesh, according to the researchers. The researchers, working with charities WATERisLIFE and iDE-Bangladesh, pulled pages from the book, put them into a holder and poured water from rivers and streams on top, straining away the bacteria. The findings were presented earlier this week at the 250th annual American Chemical Society conference in Boston.
“In Africa, we wanted to see if the filters would work on ‘real water,’ not water purposely contaminated in the lab,” Dankovich told the American Chemical Society. “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.
“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 U.S. drinking water.”
How does it work?
Dankovich said the microbes are killed when they absorb the silver or copper ions from the nanoparticles in the paper. “Only a few milligrams of silver are needed to be highly antibacterial,” she told The Post. Each filter can be used to purify 100 liters of liquid, meaning each page could last for weeks and each book could last for about a year, according to the researchers.
Some metal particles do seep through the paper, Dankovich said, but the amount is still “well below” the limits set by the Environmental Protection Agency and World Health Organization.
Kyle Doudrick, who studies sustainable water treatment at Notre Dame’s College of Engineering, told BBC News that although the science is important, the key is making sure people understand how to use the filters and when to replace them.
It’s also unclear whether the nanoparticles would kill other disease-causing microorganisms, including viruses.
“Overall, out of all the technologies that are available — ceramic filters, UV sterilization and so on — this is a promising one because it’s cheap and it’s a catchy idea that people can get hold of and understand,” Doudrick said.
Dankovich came up with the idea while working at McGill University in Montreal and developed it later at the University of Virginia.
The book is still in the development phase and will require many more laboratory tests and field trials over the next year, Dankovich said, but within the next couple years, Dankovich, working with students from Carnegie Mellon, hopes to have the product on the market. She said her goal is to provide each filter for less than 10 cents a piece.
“I hope that these filters will one day help improve the health of millions of people around the world,” she said.