Ina Fried

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Solving Bill Gates’s Potty Problem

It’s not often you hear toilet talk from Bill Gates.

But this week, the Microsoft founder is focused on toilets. Heck, he even used the word “poop” in a tweet.

Michael Hanson/Bill & Melinda Gates Foundation

“4 out of 10 people don’t have a safe way to poop – that’s 2.6 billion!” Gates said in a Twitter posting on Monday.

Gates and his foundation have sponsored a “Reinvent the Toilet” challenge to help create innovations in toilet technology. The effort began last year with $400,000 grants to eight universities with ideas on how to create a better bowl.

The criteria set out by the Gates Foundation are pretty strict. The toilets have to be hygenic and sustainable, discharge no pollutants, generate energy, recover nutrients and only need a tiny amount of water. Oh yeah, and they also need to have a cost of operation of a nickel per person per day.

This week, the eight grant recipients are gathering in Seattle to compare notes. Two of the eight have working prototypes; the other six are all making good progress.

The projects are pretty impressive. Here is a sampling:

From the Delft University of Technology in the Netherlands comes a toilet that uses microwave technology to transform human waste into electricity.

A Swiss team has a working model of a urine-diverting toilet (seen here) that recovers the water used to allow flushing, thanks to a gravity-driven biological membrane.

Michael Hanson/Bill & Melinda Gates Foundation

Researchers at Canada’s University of Toronto are proposing a technology to treat solid waste within 24 hours through dehydration and smoldering that sanitizes.

Also using combustion is a project from the National University of Singapore that uses biological charcoal to burn solid waste, while boiling urine and using carbon to create purified water.

A team at Cal Tech is proposing a solar-powered toilet that generates hydrogen and electricity, with the solar panel powering an electrochemical reactor to break down water and human waste into hydrogen gas, which in turn can serve as a backup power source.

Update, 3:37 p.m.: Gates has now posted a blog with his own take on the toilet competition.

“When you think about it, the flush toilet is actually a pretty outdated sanitation solution,” Gates wrote. Gates said that the flush toilet was a breakthrough back when it was created in the 1700s by a Scottish mathematician. The toilet saved millions of lives, Gates concedes, by preventing diseases such as cholera.

“But the fact that four of every 10 people still don’t have access to flush toilets proves that—even today—it is a solution too expensive for much of the world,” Gates wrote. “And in an era where water is becoming increasingly precious, flush toilets that require 10 times more water than our daily drinking water requirement are no longer a smart or sustainable solution.”

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