GTRI Solar Latrine
“Forty percent of the world’s population (approximately 2.6 billion people) has no sanitation. For those with sanitation in developing countries, a toilet is frequently a pit dug in the ground surrounded by a brick outhouse. Although this is better than nothing, this type of facility can contaminate the groundwater and is not a viable option for areas that flood or have rocky soil.
As part of a collaboration with Emory University’s Center for Global Safe Water, researchers from GTRI are developing a new dry sanitation system that will use solar energy to generate enough heat to kill harmful microorganisms in human feces. Kevin Caravati, a senior research scientist at GTRI, is leading the project with Dr. Christine Moe and Robert Dreibelbis
from Emory, who are advising from the public health side. Researchers from the Georgia Tech School of Civil and Environmental Engineering, Georgia Tech College of Architecture, Georgia Tech College of Management and
Georgia Tech Engineering Students Without Borders are also participating.
Constructing an outdoor sanitation system means building a brick chamber about 2 feet high. When half of the chamber fi lls up, the other side is used until it’s full. During storage, the feces turn into compost and are eventually removed and shoveled onto fields as fertilizer. Problems arise if the compost
hasn’t been heated to temperatures over 140 degrees Fahrenheit because pathogens such as the parasitic worm Ascaris will not be killed. “We are not trying to dispose of the feces, we’re trying to cook it,” said Caravati. “To get the temperature high enough to kill the harmful microorganisms, we had to stop thinking about toilets and more about
solar ovens that reach temperatures over 300 degrees Fahrenheit.”
Appropriate Technology Design Team
Solar Latrine Summary
External Links
Project Summary
Many communities around the world face similar obstacles to sustainable development. Common issues relate to sanitation, water distribution, and energy. It is the mission of the appropriate technology design team (ATDT) to develop new technologies to address these issues. Since 2006 the ATDT has been working in conjunction with the Georgia Tech Research Institute (GTRI). Their projects include the development of a Solar Latrine to eliminate bacteria and parasites from feces. In addition, the ATDT has worked in a partnership with Yellowstone National Park to develop a high efficiency, low cost water distribution system.
Members of the Solar Latrine Research Team with prototype.
This past summer, Brad Davis, an undergraduate building construction student and Calvin Johnson, an undergraduate management student and wide receiver on the Georgia Tech Yellow Jackets football team, studied existing solar latrines and designed two new prototypes that produced enough heat to kill the microorganisms. The students placed a Plexiglas® sheet on top of the pit to allow heat to enter the chamber
and trap it inside. The researchers also positioned tin panels around the outside to reflect available sunlight into the chamber and used a Fresnel lens to concentrate the solar light to reduce the amount of time needed to kill the organisms. Fresnel lenses have been used in lighthouses and as solar collectors for photovoltaic cells.
To keep the cost of each latrine under $100, the prototype systems were designed with materials available in most villages, such as wood and brick. At Georgia Tech, the researchers used bicycle tubes for gaskets and other easily-obtainable parts such as bleach bottles and scrap wood.
In early 2006, the Emory research team, in collaboration with the Centers or Disease Control and Prevention’s Office of Global Health and Sumaj Huasi (a nonprofit organization in Bolivia dedicated to improved housing), won a Development Marketplace Award from the World Bank to develop
and implement better, aff ordable sanitation options for Bolivia. Emory nvestigators asked Caravati and his colleagues for engineering expertise to help meet this challenge. The collaborative team plans to travel to
Bolivia in early 2007 and work with local sanitary engineers to build demonstration models in communities in the Andes Mountains, about 14,000 feet above sea level.”
-2006 GTRI Annual Report
Yellowstone Pump Analysis
Due to rising energy costs, Yellowstone National Park has asked Georgia Tech Research Institute, or GTRI, to analyze their waste water and water distribution system and make suggestions to save money while also considering environmentally friendly options.  Primarily, the focus is on the pumps and motors of the system and figuring out how to increase their efficiency and lower cost.  This may include taking out some of the old pumps and putting in new pumps that are more efficient and meet the actual demands of the system.  GTRI scientist Kevin Caravati has asked for the help of ESWB students on this project and provides the technical advice and guidance.  The group of ESWB students are actively researching pump analysis techniques and developing potential methods and solutions for the cost issue.  Upon completion of the analysis, the group will give a recommendation to Yellowstone that would include the conclusions and the basis for these conclusions.  The group would then be in continuous discussion with Yellowstone if any adjustment to the proposed conclusions is needed.