In partnership with a non-profit organization, a group of US researchers created a book with silver-impregnated pages that may be used to filter contaminated water. One page from this ‘drinkable book’ can possibly filter up to 100 litres of drinking water, making it a cost-effective and long-term solution for populations with severe sanitation issues. Waterborne infections like typhoid and diarrhoea kill 1.5 million people each year throughout the world. Poor sanitation or treatment facilities are mostly to blame, with poor hygiene habits also contributing to the proliferation of hazardous organisms such as Escherichia coli in water supplies. Theresa Dankovich of Carnegie Mellon University recognized the effectiveness of silver as an antibacterial and utilized it to create the concept of a book that could both teach basic hygiene practices and cleanse water. Dankovich constructed a page made of cellulose infused with silver nanoparticles during her PhD at McGill University. She was also able to dope the paper with very inexpensive copper nanoparticles after a postdoctoral term at the University of Virginia (UVA). ‘The paper is incredibly thick and robust, and it only has around one weight percent of silver in it,’ Dankovich said at the 250th American Chemical Society National Meeting & Exposition in Boston, Massachusetts. ‘Bacteria pass through it, absorbing silver ions and die as a result.’ Dankovich and her colleagues at UVA began testing their filter pages in South Africa’s Limpopo area in 2013. According to Dankovich, one of the sample locations was an urban stream that did not have the best cleanliness. ‘Raw sewage… was simply put into it,’ she explained. From an initial value of around 200,000 colony-forming units (CFU) per 100 ml, the filter pages were able to reduce the level of E coli in treated water to fewer than 10 CFU per 100 ml. Further field testing efforts in northern Ghana and Bangladesh with the non-profit WATERisLIFE reveal that the silver-doped paper can remove up to 99.9% of the E coli germs contained in a sample. Although Stuart Kahn of the University of New South Wales in Australia, who was not involved in the study, praises the team’s efforts, he is concerned that consumers may not be able to identify when enough bacteria has been eliminated and the water is safe to drink. ‘Any initiative to give clean, safe drinking water to populations in need should be commended,’ adds Kahn. ‘If someone could find a dependable way of indicating when disinfection has been performed successfully and when it has not, the notion would be significantly improved.’
