The Green Latrine
University of Massachusetts professor Caitlyn Butler piloted the “Green Latrine” in Agona Nyakrom, Ghana this past spring as a way to deal with health risks, farming needs and as a way to create energy.
Butler, an assistant civil and environmental engineering professor, created her Green Latrine or Microbial Fuel Cell Latrine to provide a method to purify human waste, while creating fertilizer for the community’s farmers and generating a small amount of electricity.
A common issue with disposing of human waste is the dangerous viruses and bacteria that can seep into the ground water allowing harmful diseases, particularly diarrhea, to spread throughout the community. However, by using the Green Latrine, in addition to accomplishing its primary goals, Butler hopes to see a decrease in public health concerns from dangerous water systems.
The latrine functions by sending solid waste into a composting chamber while the liquid waste is filtered through.
The latrine also operates like a battery with both a cathode and an anode.
If there is enough oxygen in the solid waste when it reaches the anode, microorganisms will digest and oxidize the harmful waste, both removing electrons and creating healthy compost. These electrons then flow to the cathode where they are used by another set of microorganisms to break down nitrates from the waste into safer compounds.
The result is lower levels of nitrates in the water system. Furthermore, the electric current generated by this process may then be used to power a light bulb in the lavatory.
Prior to teaching at UMass, Butler was an assistant professor at Arizona State University. In her time there, she became well acquainted with a program called GlobalResolve, whose mission she said is “to create sustainable technology in the developing world”.
As her idea of the Green Latrine developed further she approached her colleagues involved in GlobalResolve and they joined forces.
Since GlobalResolve had already been working with the Agona Nyakrom community in Ghana for some years, Butler and her team were able to begin immediately, devoting their time to implementing and improving their design in hopes of installing the latrine in other communities as soon as possible.
The Agona Nyakrom community was “generally pretty interested and excited to have a new and novel thing being done,” said Butler.
Since its installation at the local secondary technical school, the latrine has been in constant use by both males and females.
“For the first couple of months, everything was going like I expected, but then there was the small issue of toilet paper,” she said, explaining that in Ghana the convention is to throw away toilet paper after use, because if placed in the bowl it may inhibit future use of the toilet.
This proved to be an unaccounted for cultural difference.
Since no garbage receptacle was put in place inside of the lavatory, trash began to accumulate on the floor surrounding the latrine. The mess then prevented many members of the community from using the latrine and thus this became an issue that Butler and her team needed to deal with from the United States.
Fixing problems that arise is an important part of engineering, Butler explained.
Butler has been assisted in her work by UMass graduate students Cynthia Castro and Joe Goodwill, and two collaborators from her previous department at Arizona State University. The team works to anticipate any issues that may come from the current design plan and prevent them from happening.
Since the pilot Green Latrine was installed in May, Butler’s focus has been on monitoring the latrine in Ghana, and strategizing ways to make it better.
Castro and Goodwill recently won the UMass Innovation Challenge MinutePitch with a proposal of a business model for the Green Latrine development. Butler is also currently seeking funding in order to continue her project, as she aims to install more “Green Latrines” in the future throughout the developing world.
Nadia Ragounath can be reached at firstname.lastname@example.org.