Reinventing the Toilet: The Gates Foundation Sponsors Universities to Develop Clean Solutions

The Bill and Melinda Gates Foundation has tackled many global problems over the past decade, but one of its biggest commitments has been helping find solutions to the problems of world sanitation.

According to the Gates Foundation, 2.5 billion people around the world don’t have safe and sustainable sanitation and have no place to put human waste.

So one thing the Gates Foundation has done the past two years is create the Reinvent the Toilet Challenge. It recently handed out awards and grants to eight colleges, universities and research institutes in the United States and Canada. The awards recognize researchers from leading universities who are developing innovative ways to manage human waste, which will help improve the health and lives of people around the world.

All of the Gates Foundation competitors met in Seattle in mid-August for a Reinvent the Toilet fair, a two-day event where teams and participants from 29 countries attended.

“We need a radical shift in how 2-1/2 billion people around the world are going to get rid of their human waste, and we need it as soon as possible,” says Karl Linden, a professor of environmental engineering at the University of Colorado Boulder, whose team was at the fair in August.

California Institute of Technology took first place in the competition, winning a $100,000 prize. Professor Michael Hoffmann and his team, which built a toilet that uses the sun to power an electrochemical reactor, breaks down water and human waste into fertilizer and hydrogen. The hydrogen can then be stored in fuel cells as energy. The treated water can be reused to flush the toilet or for irrigation purposes.

Second place in the competition went to Loughborough University in Leicestershire, UK, for a toilet that produces biological, charcoal, minerals and clean water. The University of Toronto won the third-place prize for a toilet that sanitizes feces and urine and recovers resources and clean water.

In addition to those winners, four other grants, totaling $3.4 million, were handed out, including one to Linder’s team at Colorado.

Here’s a look at three of the winners and their innovations:

CalTech: Clement Cid, a Ph.D candidate, says about 15 months ago, Hoffmann and a group of students began trying to figure out how they might tackle the challenges the Gates Foundation laid out.

Part of the challenge’s rules was the sanitation systems had to work off the grid when it came to power, water and sewage; it had to disinfect within 24 hours, and the system had to cost less than five cents per person per day.

“We worked on a lot of different possibilities before we hit on something that might work,” Cid says, in an interview with ThomasNet Green & Clean. “We tried building a system with real wastewater first, but then the idea came up to use electrochemical reactors.”


Clement Cid, a PH.D candidate at California Institute of Technology, poses with his team’s winning entry in the Gates Foundation’s Reinvent the Toilet Challenge in Seattle in August.

Cid says electrochemical reactors have been used before for water treatment and chlorine generation, but had never been used for solar-powered sanitation. As you can see in the video below, there are no mechanical parts in CalTech’s system. “The waterflow is by gravity,” Cid says.

The CalTech system is completely powered by incoming solar light, which is captured by photovoltaic panels. In a single day, enough solar energy and battery power can run the waste treatment system.

In addition to being able to treat and disinfect human waste, the system can also be used to produce hydrogen and fertilizer. Cid compared the disinfecting to “a baking process.”

“One of the good things about our system is that the core of the system, the metal plates involved, can be made locally wherever the system is,” Cid says. “And once the system is running, you just need to rinse it every month, and if the pipes get clogged, you need only to unclog them.”

Cid says the full protoype system, which he estimates will cost less than $2,000, will be ready by December 2013 and brought to a country in Africa or India for testing.

University of Colorado at Boulder: Linder’s team at Colorado received a $780,000 grant for their project involving a solar toilet that concentrates, sunlight via a dish and concentrator, to disinfect liquid and solid waste and produce biological charcoal (biochar), which can be used as a replacement for wood charcoal or chemical fertilizers.

“I talked to professors in chemical engineering, and we agreed [on] a thermal solar process to turn waste into something usable, but we didn’t know if we could create a process that can stabilize waste within 24 hours,” Linden says. “When we started writing our proposal for (the Gates challenge) in May, we came up with some crazy ideas. But we heard back from them, and they liked them and told us to keep going.”

The team from Boulder created a concentrator that gets to a high enough temperature (400 to 700 deg C) that creates a furnace to pyrolysis (or burn) fecal material. When light gets released, Linden explains, the photons will heat up the reaction chamber.

This solar concentrator is about 3 feet wide and will be located next to an outhouse and collect solar energy and then concentrate it into a small area (1 to 2 cm2) and direct it with the use of fiber-optics.

The team has gotten a little more than half of the grant money so far, but Linden says they now have to prove each component of the system (the solar collector, the reaction chamber and the biochar capability) can work on its own.

They expect to have a prototype ready by next December.


Billionaire philanthropist Bill Gates and the team from the University of Toronto introduce the school’s third-place entry.

University of Toronto: Professor Yu-Ling Cheng and the team from Toronto developed an integrated mini-chemical plant, where solid and liquid waste are separated first. The solid waste is then smoldered, while the liquid, which has solid contaminants in it, is filtered out at the bottom of a sand column. Any solid contaminants in the liquid is skimmed off and smoldered, as well.

We had to try to capture the chemicals and water content in human waste, which is not easy,” says Cheng, a professor of chemical engineering. “And you had to come up with a system that people would want to use, too.”

A prototype is scheduled to be completed by December 2013.

Whether any one of these sanitation “solutions” is the ultimate answer to the global sanitation challenge won’t be known for a while, but what Bill Gates said at the fair rings true:

“All the participants are united by a common desire to create a better world –- a world where no child dies needlessly from a lack of safe sanitation and where all people can live healthy, dignified lives.”



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