The project sounds simple enough: design a new toilet for use in developing countries, where access to running water, electricity and sewage is limited.
But the details are daunting. The human waste needs to be processed and sanitized, and it can't spill out during a monsoon or collect in a gutter. The toilet should generate a useful byproduct, such as a fertilizer. And it needs to be cheap enough that it's affordable for people who live on minuscule incomes of a dollar or less each day.
That's the challenge facing chemical engineer Yu-Ling Cheng and her research team at the University of Toronto.
"The [Gates Foundation's]requirements seemed to be, well, almost impossible," Dr. Cheng said. "But that just forces you to look at things in a new way."
The Bill and Melinda Gates Foundation announced it will offer $400,000 (U.S.) to teams at eight universities around the world to reinvent the toilet for use in developing countries. Dr. Cheng's team was the only one in Canada to receive funding as part of the project.
The need for a new kind of toilet is overwhelming in the developing world, said Frank Rijsberman, director of the Gates Foundation's water, sanitation and hygiene program. "The flush toilet has been an incredibly important public health advance," he said. "But it doesn't reach poor people."
An estimated 2.6 billion people don't have access to safe and sanitary toilets, according to Unicef statistics, and 1.2 billion of them have no toilet access at all, forcing them to use open fields or alleys. That contributes to the spread of diarrheal diseases such as cholera, rotavirus and E. coli, which kill more children than AIDS, malaria and measles combined, the agency says.
Dr. Cheng's team proposes to build a toilet that can dehydrate feces and smoulder them - like charcoal - to sanitize them within 24 hours. The powdery byproduct can then be used as an agricultural fertilizer. The toilet will also filter urine through a membrane, then disinfect it using ultraviolet radiation.
In addition to all the technical specifications, Dr. Cheng's team is aiming to make the toilet something people will actually want to use. That means paying careful attention to what it will look like, making sure it doesn't smell or attract bugs, and finding a way to generate light without electricity so it can be used safely at night. The team is even thinking about where the toilets might be placed in a community to maximize their use.
"That's not as trivial as you might think," Dr. Cheng said. "From a Western perspective, you might expect, just make a nice clean toilet, and people will use it. But that's not necessarily true."
As an example, Dr. Cheng cites her visit to a village in India, where she noticed people continued to walk to a field to defecate, despite the presence of some basic toilets nearby. The reason for this was practical, she said. They could pick up firewood on their way back from the field.
Dr. Cheng said she's looking into offering mobile-phone minutes to people as an incentive for using one of her team's toilets - and a payment for their contribution toward the fertilizer it will produce.
Each funded team has a year to build a prototype of their system before presenting their products at a conference in August 2012 and vying for further funding. Mr. Rijsberman said he hopes the project will result in an improved toilet that's ready for use in the developing world in three to four years.
And he adds there's no reason they can't be adopted in developed countries as well.
"How much sense does it make even in Canada to clean the water to drinking-water quality and then flush it back down again?" he said. "Frankly, this really makes a lot of sense for other parts of the world."