AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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PM2.5, OC, EC, CO, and CO2 Emissions from Briquettes Made with Human Waste
WYATT CHAMPION, Lupita Montoya, University of Colorado Boulder
Abstract Number: 685 Working Group: Indoor Aerosols
Abstract There is widespread scarcity of reliable energy sources as well as sustainable means of human solid waste disposal in the developing world. Solving these two significant challenges has been the object of many efforts. Among the proposed solutions, the waste-to-energy movement has emerged. Some research and on-the-field efforts have been focused on the production of briquettes made from char derived from human feces (biochar). Previous work in our lab (Ward et at., 2014) demonstrated that briquettes made from biochar and low-cost binding material can contain energy on par with charcoal commercially available in places like Africa.
The present study reports results from controlled combustion of briquettes made from human solid waste using a cookstove and following a Water Boiling Test protocol. For comparison, charcoal, wood, and coal types used by the Navajo Nation were also evaluated. Filter samples collected fine particulate matter (PM2.5) for gravimetric and organic and elemental carbon (OC and EC) analyses. Gas monitoring was also conducted for carbon monoxide (CO) and carbon dioxide (CO2).
Results showed that biochar briquettes emitted higher PM2.5, OC, CO, and CO2 per unit energy (g/MJ) delivered to the cooking pot, compared to the Navajo fuels tested. For example, the biochar briquettes emitted 19-fold higher PM2.5 and 65-fold higher OC per energy delivered, compared to the wood tested. The biochar briquettes also had lower modified combustion efficiency, compared to the other fuels tested (87% vs. 95%, respectively). Therefore, the formulation of biochar briquettes tested here resulted in high emissions, in part due to observed low modified combustion efficiency. Continuing efforts to optimize this waste-to-energy alternative are presently being pursued in Ghana. Recent results from these efforts will be presented.
Reference: Ward, B.J., Yacob T.W., Montoya L.D. (2014). “Evaluation of Solid Fuel Char Briquettes from Human Waste”, Environmental Science and Technology, 48 (16):9852–9858.