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Portable Sewage System Turns Waste Into Drinking Water

Self-sustaining waste treatment machine also produces excess energy for use by the local community.

Ross Brooks
Ross Brooks on July 29, 2013. @greenidealism

Duke’s Pratt School of Engineering was the winner of this year’s Bill and Melinda Gates Foundation’s Reinvent the Toilet competition, receiving a grant of $1.18 million to build a sewage processing system that fits inside a shipping container.

While not technically a toilet, the sewage processing system is extremely efficient and could change the way people around the world deal with their waste. Capable of dealing with a community of 1200 people, the system provides an alternative to simply dumping waste in rivers.

supercritical-sanitation-system-3

Communities using the system would have two options, having their cisterns pumped or physically carrying waste to the container.

Once in the container, the waste would be forced into a “supercritical” state – this is when water is heated to temperatures of over 705°F and pressures of more than 3200 pounds per square inch applied. Water in this state flows like a gas but is still able to dissolve other substances like a liquid.

What this means is that the suspended sewage can be dissolved, and with the addition of oxygen, it’s also possible to oxidize (i.e., burn) the sewage sludge – resulting in a sterile combination of water, carbon dioxide and salts.

supercritical-sanitation-system

The process of supercritical water oxidation (SCWO) also produces excess heat, despite the presence of water. Energy is only needed to start the system initially, once it reaches a certain temperature the remaining hot water may be supplied to the community directly or used to power an electrical generator.

Duke’s Pratt School of Engineering

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Ross is a freelance writer who specializes in topics about the environment, architecture, art, design and creative tech. He is passionate about making a difference with his writing, whether that’s to encourage social change, promote a great idea, or just share a little bit of beauty with the world. You can also find his work on Inhabitat and Techly.com.au.

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