CU-Boulder team wins nearly $780,000
‘Reinvent the Toilet’ grant from Gates Foundation

An interdisciplinary team of student and faculty engineers from the University of Colorado Boulder has won a grant from the Bill and Melinda Gates Foundation for its proposal to develop a solar-biochar toilet for use in developing countries throughout the world.

The grant is part of the Reinvent the Toilet Challenge, or RTTC, initiated by the Gates Foundation to address a sanitation challenge affecting nearly 40 percent of the world’s population.

CU-Boulder, which was awarded one of four grants in the second round announced today, will receive nearly $780,000 from the Gates Foundation over a 16-month period starting Sept. 1. CU joins last year’s grantees Caltech and Stanford as the only U.S. universities to receive an RTTC award.

The ol’ outhouse

Environmental engineering professors Karl Linden and R. Scott Summers will join with chemical and biological engineering professor Al Weimer on the project.

Biochar is a highly porous charcoal made from organic waste. The idea proposed by the CU team involves using concentrated sunlight delivered through a bundle of fiber-optic cables to heat and decompose toilet waste for reuse in improving agricultural soils.

“This project integrates areas of expertise at CU in solar-thermal processes, disinfection and biochar that would not typically work together and creates a great team to tackle such a complex and important problem as sustainable sanitation solutions in developing countries,” said Linden, who is the principal investigator on the project.

Environmental engineering graduate student Ryan Mahoney and postdoctoral researcher Tesfa Yacob, who received his doctorate in civil engineering from CU-Boulder in May, along with Richard “Chip” Fisher, a professional research assistant in Weimer’s chemical engineering group, also will be involved. Two expert consultants round out the team, one focusing on solar-thermal design and one on sanitation and hygiene in developing communities.

An upgrade

A preliminary analysis indicates that a household-sized system for a family of four could be developed at a cost of 5 to 10 cents per person per day.  An intermediate-scale system for community facilities also will be evaluated as part of the grant.

Linden and Summers are working on other environmental engineering projects for developing communities, including investigating hydrothermal biochar production and low-cost water filtration and treatment technologies.  Weimer will add expertise in the area of solar-thermal processing and reactor design, which he has tested extensively for the development of alternative fuels.

“This project is also very student-driven,” said Linden. “Students with classroom and field-based experiences in our Engineering for Developing Communities program have provided some excellent ideas, expertise and enthusiasm to make this project possible.”

Environmental engineering doctoral students Josh Kearns, Kyle Shimabaku and Sara Beck are also contributing to the project.