Touted by its creators as an "appealing, affordable and safe solution for washers as well as wipers," the Blue Diversion Toilet is designed to provide off-grid sanitation for low-income areas. Not only does the stand-alone unit filter water for reuse on site, but it also separates urine and solid waste to be filtered and reused as fertilizer at a community-scale resource recovery plant. Funded by the Bill and Melinda Gates Foundation, the creators hope that this will provide affordable sanitation while attracting investment from entrepreneurs with its unusual business model.
According to the World Health Organization, some 2.5 billion people lack access to improved (ie., safe, clean) sanitation facilities, and so in 2011 the Bill and Melinda Gates Foundation launched the “Reinvent the Toilet Challenge.” The challenge funds projects which are working to develop a next-generation off-grid toilet that “Removes germs from human waste and recovers valuable resources such as energy, clean water, and nutrients… Promotes sustainable and financially profitable sanitation services and businesses that operate in poor, urban settings,” and costs less than $0.05 cents per user per day.
A team from Eawag (the Swiss Federal Institute of Aquatic Science and Technology) partnered with Austrian design firm EOOS, and the Blue Diversion Toilet was born. The single unit separates undiluted urine, feces, and water into separate containers below the pan. The water that is used for flushing is then filtered through a self-cleaning multi-barrier treatment system to make it safe and clean for washing. The same water can be used around 50 times a day, and power for the pumps and electronics within the toilet is provided by photovoltaic panels atop the unit.
The urine and feces, meanwhile, are collected twice a week by a service person who safely transports the sealed waste containers to a community-scale resource recovery plant. Here, the nutrients from the urine are extracted through partial nutrification and distillation to create “marketable urine-based fertilizer,” while the feces are treated and composted.
The toilet has been successfully tested in trials in Uganda and Kenya to largely positive feedback, and the team is now working on developing a sit-down version as well as one that will have onsite resource recovery, dubbed the Autarky Toilet. They are also seeking support to begin large-scale production of the toilets, which they hope to market for around $500.