MU engineers look to export low-cost toilets

COLUMBIA, Mo. -- University of Missouri engineers are teaming up with colleagues at Duke University to create a low-cost toilet for developing countries with water shortages.

The Columbia Missourian reported that MU's Carbon Recycling Center is participating in the Reinvent the Toilet Challenge sponsored by the Bill and Melinda Gates Foundation. The challenge is how to develop a device that can conserve water for use in areas where clean drinking water is scarce.

The center's research project heats and pressurizes the waste water at extremely high temperatures in an effort to produce sterile water that can be reused.

"The big idea is that when it's done, you're going to be able be able to recover all the water," said Brook Remington, an undergraduate student who works in the lab. "You're going to end up with clean, sterile water at the end."

The water is heated to about 1,100 degrees Fahrenheit and 250 times the normal atmospheric pressure, said lab worker Nikolas Wilkinson. Those temperatures would normally convert liquid into gas, but the high pressure prevents that reaction, creating what is known as supercritical water.

Like a gas, the water spreads out to take up as much space as possible, but it also can dissolve solids -- as it would in liquid form.

"If you had a giant wood log, it would only burn at the surface," Wilkinson said. "Since we can dissolve it in there, we have a lot more surface area per mass, and so we can get really high reaction rates."

To test the low-cost waste disposal system, researchers have developed fake feces made of soybean paste, cellulose, yeast and other chemicals. The fecal substitute resembles hummus in appearance and texture.

As the waste is consumed, the water cools, leaving only clean water, carbon dioxide and a few solids. The excess heat can be used to preheat water for the next "flush," while, the solids byproducts, such as nitrogen and phosphorus, could be used for fertilizer.

Still, significant hurdles remain before the device could be used widely.

Supercritical water is highly corrosive, meaning the device's metal pipes and joints must be replaced often. The waste tube also tends to clog, Wilkinson said.

A recent Missouri graduate who is now a postdoctoral researcher at Duke will work on enlarging the prototypes created in Columbia in hopes of having the product ready for use by March 2014.

The private school in Durham, N.C. -- Melinda Gates' alma mater -- received a $1.2 million grant from the charitable foundation created by the Microsoft co-founder and his wife. Missouri will use $200,000 of that award for its research.

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Information from: Columbia Missourian, http://www.columbiamissourian.com