Duke University, Ph.D.
EREF Scholar 2012
A New Hazard Assessment Protocol for Coal Combustion Products
Project Description (while EREF Scholar):
When coal is burned for energy, large amounts of solid wastes called coal combustion products (CCPs) are generated during the combustion and flue gas scrubbing processes. CCPs consist of a mixture of solid wastes, including fly ash from fine particulate collection devices; bottom ash from the coal-burning boiler; and sludge wastes from desulfurization processes. U.S. coal-fired power plants generate a massive amount of CCP waste each year—approximately 136 million tons annually. While approximately 61 million tons of CCP waste is recycled in various ways, the majority of this waste is disposed of in landfills or storage ponds. Currently the EPA does not regulate CCPs as a hazardous waste. As a consequence of this policy, CCP impoundments are often unlined and may be susceptible to leaks and failures due to improper maintenance.
CCPs contain high levels of toxic elements, including mercury (Hg), arsenic (As) and selenium (Se), that are harmful to the environment. The current hazard assessment method for CCPs is the EPA’s Toxicity Characteristic Leaching Protocol (TCLP), a standardized leaching procedure. This protocol does not take into account factors such as microbial activity that would influence transformations involving contaminant elements. Thus the TCLP method may greatly underestimate the true hazard of CCPs in the environment.
The goal of Grace’s research is to develop a new method for the hazard assessment of CCPs. Her method will account for Hg-ligand interactions, redox conditions, and microbial processes—all of which influence toxic trace element mobility and bioavailability in the environment.
Grace grew up in the small town of Crozet, Virginia in the foothills of the Blue Ridge Mountains. She was homeschooled until age 16 when she started her college education at Piedmont Virginia Community College. Grace transferred to Virginia Commonwealth University (VCU) where she studied both Chemistry and Philosophy. She developed an interest in environmental chemistry through her involvement with the VCU Life Sciences Outreach Education Program where she helped organize environmental education programs for Richmond area high school and middle school students. After college, Grace worked as a bench chemist in a pharmaceutical contract lab, but eventually found her way back to her true love of environmental chemistry at Duke University where she received her PhD in Environmental Engineering in May 2015. Grace’s research at Duke focused on the environmental transformations of trace element contaminants associated with coal combustion products.
She now works as a Postdoctoral Fellow in the Microbial Ecology Lab at the Smithsonian Environmental Research Center in Edgewater, MD where she investigates the biogeochemical parameters that control methylmercury production in the environment.
In her spare time, Grace enjoys baking, gardening, and reading all kinds of books.
Click here to view a poster that Grace presented at a Women in Science and Engineering (WISE) research symposium at Duke University in December 2012.
Click here to view a project that was a collaboration between the Duke University lab, the Vengosh group in the Duke Earth and Ocean Sciences department and representatives from the NC DENR. The researchers looked at the environmental impact of coal ash pond effluent on NC water resources.
Click here to view an article published in Elsevier Journal that was a collaboration with Duke University CEEE, RTI International Analytical Sciences, the University of Kentucky Center for Applied Energy Research and the Duke University Division of Earth and Ocean Sciences.
Click here to view the supporting information for the above article.
Schwartz, Grace E., et al. “Impacts of Coal Ash on Methylmercury Production and the Methylating Microbial Community in Anaerobic Sediment Slurries.” Environ. Sci.: Processes Impacts, vol. 18, no. 11, 2016, pp. 1427–1439., doi:10.1039/c6em00458j
Schwartz, G. E., Hower, J. C., Phillips, A. L., Rivera, N., Vengosh, A., & Hsu-Kim, H. (2018). Ranking Coal Ash Materials for Their Potential to Leach Arsenic and Selenium: Relative Importance of Ash Chemistry and Site Biogeochemistry. Environmental Engineering Science., doi.org/10.1089/ees.2017.0347