How does it work?
Clean toilets for slums The Blue Diversion Toilet developed by Eawag may resolve the problem of inadequate sanitation in developing countries. By Daniel Saraga, Infographic: Ikonaut
1. The problem More than 2.5 billion people go to the toilet in either the open air or unsanitary toilets. The lack of proper sanitation facilities leads to polluted waterways and cases of severe diarrhoea, which kills 1.8 million people annually. 4.8 bn 66%
2.5 bn 34%
3. An automatic toilet The Blue Diversion Toilet works without access to water, sewer or electricity networks. Urine and faeces are separated and stored in containers to be recycled later. Water used for washing hands and for flushing the toilet is recovered, sterilised on-site and then reused. Disinfection is done through an ultra-filtration technique developed at Eawag and powered by a small 60 W solar panel.
2. The project The water research institute Eawag near Zurich has been developing the Blue Diversion Toilet since 2011, thanks to a contribution of USD 4.5 million for the “Reinvent the Toilet Challenge” by the Bill and Melinda Gates Foundation. In March 2015 the toilet was nominated as one of the Designs of the Year 2015 by the London Design Museum.
4. The economic model Waste is collected twice a week and taken to a processing plant. The urine undergoes nitrification and is transformed into concentrated ammonium nitrate, a common agricultural fertiliser. Faeces are partially burnt, formed into bricks and used as heating fuel. The trade of these two products constitutes a viable economic model for the owner of the toilet. And with the cost of using the toilet at around five cents, it is acceptable for local populations. Autarky, a new project at Eawag, aims to introduce on-site transformation of the waste into tradable products, particularly by stabilising urine using lime.
Swiss National Science Foundation – Swiss Academies: Horizons No. 106
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