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Students at Duke’s Pratt School of Engineering are hard at work conquering a poop problem. The students recently received a grant of $1.18 million from the Bill and Melinda Gates Foundation’s “Reinvent the Toilet” competition for their innovative sewage processing system that fits inside a 20-foot shipping container. The system can help developing communities manage their own raw sewage, converting their waste to usable heat, water and energy.
Small enough to transport in a shipping container, the Duke team’s system can effectively treat the raw sewage of a community of 1200 people. The system is geared toward communities with no systems in place, other than dumping directly into the closest river or body of water, thus risking the contamination of water supply.
Inside the 20-foot shipping container, the waste passes through a complex system of heat and pressure, reducing it to Supercritical Water Oxidization, which is attained at 705 degrees Fahrenheit and with 3,200 pounds per square inch of pressure. The supercritical water is similar to gas, but also has the liquid property of being able to dissolve things. Combined with the sewage and oxygen, the process burns off the sludge and creates sterile water, carbon dioxide and salt, while producing heat. The heat can be cycled back into the sewage system, or used as a power source.
With the Gates grant, the Duke students will be able to further explore the sewage system, which could bring critical sewage control to developing communities, while also creating usable water and power.