A new loo

diagram of pHree Loo disinfecting toiletPhoto by Anastasia Victor-FaichneyAiming to improve sanitation services in developing countries, the Bill and Melinda Gates Foundation challenged engineers to make toilets clean, affordable and sustainable for the 2.5 billion people—40 percent of the world’s population—who lack access to modern latrines. In response, environmental engineering professor Kara Nelson and postdoctoral researcher Temitope Ogunyoku developed a toilet that safely disinfects waste.

Called the pHree Loo, their design uses a two-step process that raises the pH of the excreta to inactivate harmful pathogens. The resulting waste, or “safe sludge,” can then be disposed of without endangering humans or the environment. Their goal is for each toilet to cost less than $50.

Over the next year, the researchers plan to refine their design, test it under actual use conditions and investigate ways to incorporate their solution into existing waste management systems. The display model, shown here, was designed to be transparent to show the toilet’s inner components. 


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