Paper filters to fight waterborne diseases

“Medicine for the soul” was reportedly written over the entrances of several great libraries throughout history – the ancient library at Thebes and the St. Gallen Abbey Library in Switzerland among them. Now, researcher Theresa Dankovich at Carnegie Mellon University has shown that books can be much more than medicine for the soul – they can actually help in the fight against waterborne diseases such as cholera, dysentery and typhoid fever.

According to the World Health Organization, more than 3.4 million people die each year from water, sanitation, and hygiene-related causes. Nearly all deaths, 99 %, occur in the developing world. This is the problem that Dankovich is trying to tackle, together with designer Brian Gartside and with support from the NGO WATERisLIFE. “The even bigger problem? Most people don’t even know that their water is unsafe to drink”, says Brian Gartside in a video.

This is why they developed the drinkable book – a book that filters water and teaches people in developing countries proper hygiene and sanitation habits. The book is printed on technologically advanced filter paper with special ink. Each of the 20 pages contains tips on good sanitation practices printed in the local language of the country in which the book is distributed. So far, books have been printed in Swahili, Dagboni, Haitian Creole, and English.

To use the book, people need to rip one of the thick pages in half and insert it into the book’s packaging, a 3D printed prototype, which serves as a filter box. They then pour water through the filter to get purified drinking water. The paper is coated with silver nanoparticles, which are lethal for bacteria.

Dankovich started working on paper filters almost eight years ago as a Ph.D. student at McGill University. “The biggest scientific challenges were the chemical treatment of the paper and proving that it could kill bacteria in laboratory tests”, she says. After many tests and improvements, Dankovich succeeded. She developed an environmentally sound method to produce the silver nanoparticles, using inexpensive and benign chemicals and processing, and showed that the resulting papers worked in the lab. Now, she was ready to see if the filters would hold up under real-world conditions: “The most exciting breakthrough happened during the first time we tested the paper filters in the field in South Africa, where the filters eliminated bacteria in contaminated streams”, she says.

Paper is the ideal material for a water filter: The pores are large enough to prevent clogging but small enough to give the antibacterial agent enough time to work on the bacteria. “I have selected a particular type of paper from paper mills that is extra strong when wet and not easily torn”, says Dankovich. Even better: The paper filters cost only about 10 cents each and are easy to produce. Each filter can clean about 100 liters of water, one drinkable book can provide clean water for up to four years.  Dankovich uses a letterpress printer and food grade ink.

So far, about 60 books have been produced, mostly for field tests, but Dankovich aims to distribute a thousand next year. She founded the non-profit pAge Drinking Paper and is looking for additional support to scale up production. One step along the way is to find a paper making facility that would adopt her paper treatment method first in a pilot study and, if possible, on a larger scale.

Dankovich has a few other ideas about how to use the technology, but for now, she has her mind set on bringing clean water to many people who need it. Her experience has been very positive: “When we were doing field tests in Ghana, we filtered the water right in the center of the rural village”, she says. “Normally when scientists perform experiments or gather samples, they are fairly isolated.” In Ghana, that was not the case. At least 30 children and a few adults gathered to see what they were doing. For Dankovich the experience was well worth all the work she performed in the lab and in the field: “The most rewarding moment was definitely getting the opportunity to deliver clean water to people in Africa.”

[embedyt]https://www.youtube.com/watch?v=qYTif9F188E[/embedyt]

  photos: Brian Gartside