BOSTON, Aug. 16, 2015 -- Human consumption of bacterially contaminated water causes millions of deaths each year throughout the world--primarily among children. While studying the material properties of paper as a graduate student, Theresa Dankovich, Ph.D., discovered and developed an inexpensive, simple and easily transportable nanotechnology-based method to purify drinking water. She calls it The Drinkable BookTM, and each page is impregnated with bacteria-killing metal nanoparticles.
Dankovich will explain her technology and reveal new results of recent field tests conducted in Africa and Bangladesh at the 250th National Meeting & Exposition of the American Chemical Society (ACS). ACS is the world's largest scientific society. The national meeting takes place here through Thursday.
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 notes. While earning her doctorate at McGill University, she found that sheets of thick filter paper embedded with silver nanoparticles could do just that, eliminating a wide variety of microorganisms, including bacteria and some viruses.
She continued her research at the University of Virginia's Center for Global Health, expanding the repertoire of embedded nanoparticles to include ones made of inexpensive copper. Dankovich also began field investigations of water purification applications 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 says. "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," Dankovich adds. "Some silver and copper will leach from the nanoparticle-coated paper, but the amount lost into the water is within minimal values and well below Environmental Protection Agency and World Health Organization drinking water limits for metals."
Last year, she formed a nonprofit company, pAge Drinking Paper. In collaboration with the nonprofit WATERisLIFE organization and Brian Gartside, a designer formerly with DDB New York and now with Deutsch, her company developed a unique product that is essentially a book comprised of pages embedded with silver 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. A page can clean up to 26 gallons (100 liters) of drinking water; a book can filter one person's water needs for four years.
Now a postdoctoral researcher at Carnegie Mellon University, Dankovich is further developing the technology and conducting more field studies in rural communities. In June, Dankovich teamed up with International Enterprises (iDE)-Bangladesh, an international nonprofit, in a field trial to explore commercialization of the silver nanoparticle paper filter for household water treatment. In several districts in southern Bangladesh, customer-focused surveys provided rich insights into easily accepted and culturally appropriate filter designs, she says, adding that the field tests continued to show significant reductions in coliform bacteria counts.
Dankovich is also connecting her chemistry expertise with industrial designers at the University of Cincinnati and with environmental engineers at Carnegie Mellon. "We have a bunch of designs, and we are trying to trim them down and keep them simple," she says. "Worldwide, many people use a 5-gallon bucket for many needs, so we are basing our approach on that type of container.
"Along with applications, our biggest current focus is to scale up, going from a lab bench experiment to a manufactured product. We have to go from 'cool chemistry' to something everyone can understand and use." (A video about the project is available at https://www.youtube.com/watch?v=qYTif9F188E.)
A press conference on this topic will be held Monday, Aug. 17, at 2 p.m. Eastern time in the Boston Convention & Exhibition Center. Reporters may check-in at Room 153B in person, or watch live on YouTube http://bit.ly/ACSLiveBoston. To ask questions online, sign in with a Google account.
Dankovich acknowledges funding from iDE-Bangladesh, Carnegie Mellon University, WATERisLIFE, NIH Fogarty International Center and Natural Sciences & Engineering Research Council of Canada.
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The Drinkable BookTM - a novel nano-enabled antibacterial paper filter for water purification in developing countries
The Drinkable BookTM contains silver nanoparticle paper filters, is printed with food grade ink, and contains a set of instructions for how and why to clean drinking water. This addresses an urgent need for inexpensive point-of-use methods to purify drinking water in developing countries to prevent the spread of waterborne illness. This project builds on our past work, which described a method to deactivate laboratory cultured bacteria by percolation through a thick paper sheet containing silver (Ag) and/or copper (Cu) nanoparticles (NP). The AgNP and CuNP papers were tested for performance in the field with water samples obtained from a variety of contaminated water sources (streams, dugout ponds, borehole wells, collected rainwater) in Limpopo, South Africa, northern Ghana, Haiti, and Kenya. The papers were analyzed with respect to their effectiveness of bacteria inactivation, turbidity reduction, and metal leaching as contaminated water percolated through the paper. There was a range of influent coliform bacteria concentrations present in the water sources, from 200 CFU/100 mL to 3,500,000 CFU/100 mL. With the lesser contaminated water sources, both AgNP & and CuNP papers showed complete inactivation of the coliform bacteria. With the more highly contaminated water sources, the AgNP papers showed near complete inactivation, with a slightly higher bacteria reduction of log 6 than the CuNP papers with log 5. For most water purification experiments, the metal loss from the sheets was minimal, with values under 0.1 ppm for Ag and 1 ppm for Cu (the current US EPA and WHO drinking water limits for Ag and Cu, respectively). These results show promise that purification of bacterially contaminated water through paper embedded with silver and/or copper nanoparticles could be an effective point-of-use water treatment.