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“Drinkable Book” Turns Dirty Water Clean for a Thirsty World

“Drinkable Book” Turns Dirty Water Clean for a Thirsty World

Pages of silver nanoparticles filter sludge from water and kill bacteria

By Matthew Gunther

drinkable book

Agroup of researchers from the US, in collaboration with a non-profit organization, has designed a book with silver-impregnated pages that can be used to filter contaminated water. One page from this ‘drinkable book’ can potentially filter up to 100 litres of drinking water and may provide a cheap, sustainable solution for communities suffering from severe sanitation problems.

Waterborne diseases, such as typhoid or diarrhoeal illnesses, kill 1.5 million people a year globally. Poor sanitation or inadequate treatment facilities are primarily to blame, with inadequate hygiene practices also leading to the growth of harmful organisms in water supplies, such as Escherichia coli.

Recognizing that silver is an effective antimicrobial, Theresa Dankovich from Carnegie Mellon University used the idea to launch the concept of a book that could both encourage proper sanitation practices and purify water. During her PhD at McGill University, Dankovich successfully created a page made from cellulose, impregnated with silver nanoparticles. Following a postdoctoral stint at the University of Virginia (UVA), she was also able to dope the paper with relatively inexpensive copper nanoparticles.

drinkable book 2‘The paper is really thick and sturdy, it has less than one weight percent of silver in it,’ explained Dankovich, speaking at the 250th ACS National Meeting & Exposition at Boston, US. ‘Bacteria percolate through it, absorb silver ions and, as a result, end up dying.’

At UVA Dankovich and her colleagues started to test their filter pages in Limpopo province in South Africa in 2013. One sample location was an urban stream that did not exactly have the best sanitation, according to Dankovich. ‘Raw sewage … was just being dumped into it,’ she said. The filter pages were able to bring the level of E coli in treated water down to less than 10 colony-forming units (CFU) per 100ml from an initial value of approximately 200,000 CFU per 100 ml. Further field testing campaigns with the non-profit organization, WATERisLIFE, in northern Ghana and Bangladesh suggest that the silverdoped paper can remove up to 99.9% of the E coli bacteria present in a sample.

investing in the reuse of treated wastewater.

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Investing In the Reuse of Treated Wastewater

BY: THE WATER FOR FOOD TEAM

370420Note171InvestInReuse01PUBLIC1Of the projected 1 billion growth in global population by 2015, 88 percent will take place in cities, nearly all of it in developing countries (UNDP 1998). Investments in urban water supply and sewerage coverage are rising, as shown in Figure 1. However, as shown in Table 1, adequate treatment for agricultural reuse with acceptable risk mitigation for human health and the environment will require further investment (World Bank and Swiss Development Corporation 2001).

While this Investment Note addresses reuse after treatment, it is critical to ensure that investments in treatment appropriate for reuse schemes will be made. Urban wastewater is well suited to agricultural reuse and landscaping because of the reliability of supply, proximity to urban markets, and its nutrient content (depending on the treatment technology). To have an impact on scarcity, reuse of wastewater must substitute for, not add to, existing uses of higher-quality water.


Moreover, reuse of treated wastewater often disproportionately benefits the poor. It must be combined with strategies to prevent or mitigate health risks from pathogens, heavy metals, pesticides, and endocrine disrupters, and environmental damage from heavy metals and salinity. Long-term institutional coordination among urban, agricultural, and environmental authorities and end users is a requirement for water reuse investments to pay off. This note outlines technological and management interventions suitable for World Bank lending.

 

                           


            

Current Issue: Africa Water & Sanitation & Hygiene July - August 2017 Vol.12 No.4