New toilet designed in NC offers hope for cleaner water

northcarolinahealthnews.orgMarch 9, 2014 

A million and a half children around the world die from diarrhea each year. That’s more kids dying from diarrhea than HIV infection and malaria combined.

It’s a stark statistic to reckon with, yet diarrhea and fecal-borne illnesses remain one of the largest public health problems in developing nations. For decades, scientists have focused on water – access, quality, cleanliness – as the way to prevent diarrhea illnesses, but scientists in the Research Triangle say that way of thinking looks at the problem all wrong.

“You’ve got to build a better toilet,” said Brian Stoner, an investigator at RTI International in Durham. “You can have perfectly clean water, but without sanitation, sludge and waste ends up near kids.” Stoner is also an adjunct professor in the Department of Electrical and Computer Engineering at Duke University.

Stonerand team members from RTI, N.C. State and Duke University have spent the past 18 months designing that toilet. As the recipient of a Gates Foundation challenge grant, Stoner and his colleagues have rethought toilet sanitation, making a prototype that is suitable for use in places with no municipal waste stream, electricity or access to water.

“There’s 2.5 billion people in the world without access to effective sanitation,” Stoner said. “I’m optimistic about this work.”

This month, they’re taking their prototype to Delhi, India, where their lab model will be part of a toilet fair attended by Delhi politicians and investors. For Stoner, a material scientist who has worked in water sanitation, the trip will be a jumping-off point to test his toilet in the field.

“I’m very excited because (the toilet project) includes multiple technical disciplines and a social aspect,” he said. “Most new technology fails because people don’t understand the social and economic needs of an area. We’ve taken that information into consideration.”

Stoner’s design is based on simple facts about human waste: The dirty things that come out of us also can be cleaning resources. Urine contains salts that can purify and sanitize like chlorine – while excrement, or solid waste, can dry and be burned as fuel.

“In many parts of the world, dung is used as a fuel source. We put those two pieces together,” he said, referring to urine and feces, “and it’s the basis for our design.”

Self-contained

This new toilet is different from the one you have in your bathroom. Stoner said the technology behind the toilets we use is 200 years old and based on the same designs put forth by Thomas Crapper, the British plumber associated with our flush system. Our toilets depend on a sideways “s” tube that pushes water up, down and back up the toilets to flush out sewer gases and move waste into municipal sewer systems.

Stoner said the new toilet uses an open-screw mechanism to push dried excrement up and into something that resembles a large camp stove, where it’s burned for fuel, converted to electricity and powers the toilet. Liquid waste is converted to salts and chlorine, which disinfects the liquid waste and converts it to nonpotable water.

In other words, the toilet is a self-cleaning, self-contained sanitation machine.

The design is meant for large urban areas in which most family dwellings do not have a toilet. Instead, these areas have communal toilets or shared bathroom facilities that dot the landscape of urban slums.

The approach is so novel that the new toilet is even getting some attention from the art world. Stoner’s design caught the eye of Steve Gottlieb, a photographer who wrote a coffee-table book on toilets called “Flush.” Gottlieb photographed RTI’s toilet team for his book, an event Stoner said was a lot of fun.

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