It may not be turning lead into gold, but a Temple University professor has been changing harmful ash into a variety of useful resources.
The Environmental Protection Agency recently awarded a bronze medal to Temple environmental engineering professor David Kargbo for his “outstanding contributions” to the research activities of the Hazardous Substance Research Centers.
The focus of Kargbo’s research is possible uses of municipal waste ash. Municipal waste ash is an unneeded byproduct of burning garbage for energy.
“They felt like the work I’m doing is important to the mission of the agency, which is protection of human health and the environment,” said Kargbo, an editorial board member of the Journal of Environmental Geology.
His research focuses on changing the ash fertilizer and a material to clean harmful mines, which he compared to other efforts to make use of waste.
“Sometimes garbage is used as a resource,” he said. “Waste-to-energy plants burn it, which in turn produces steam. The steam turns turbines, and the turbines generate electricity.”
The waste ash is often discarded in landfills. As space for this product becomes scarcer, Kargbo discovered a way to use the waste ash and clean up the environment at the same time.
Kargbo creaed a substance called zeolite from the municipal waste ash using equipment specially designed by Temple’s Chemistry department.
“Zeolites come in different forms,” said Kargbo. “But they all have the general property to pull chemicals and moisture towards them. They are widely used in industry and by individuals on a daily basis. They are used in fertilizers as they hold nutrients for the plant roots to absorb, and in waste-water treatment plants to treat contaminated water.”
Kargbo is the first environmental engineer to create zeolites from municipal waste ash. He also proved that the ash is not toxic, as most people believed. The ash passed the Toxicity Characteristic Leaching Procedure test, an assessment created by the EPA to determine whether or not a waste is hazardous.
The discovery of a new method to create zeolites could create cheaper and cleaner methods of fertilizing crops and decontaminating water.
“The next step is to see how much contamination the zeolites can contain. Then we have to develop standards on how to use the ash that people are comfortable with,” Kargbo said. “It’s one thing to generate something. It’s another thing to make people understand it is a good thing.”
Kargbo performed further research on the possibility of using the municipal waste ash to prevent acid mine drainage, a phenomenon in which acidic substances from mining sites find their way into water sources.
“In Pennsylvania alone, the estimated cost to reclaim sites impacted by acid mine drainage is over $15 billion,” Kargbo said. “As landfill space for the ash becomes very scarce, we figured out a way to deal with the ash and also help to solve the acid mine drainage problem.”
“The ash is alkaline because in a bid to prevent the release of toxic acidic gases during garbage burning, plants add lime slurry, a highly alkaline material,” he said. “Because waste ash is highly alkaline, it can be used to neutralize acid mine drainage.
“Right now my central focus is trying to help communities solve problems with acid mine drainage,” he said.
Using municipal waste ash to prevent this phenomenon is only one part of the solution. Kargbo performs accelerated weathering “to better understand how rocks at these mine sites weather and release acidity.”
“In addition to acid mine drainage, we are also doing research on calcite and how it can be used to clean up the environment,” Kargbo said.
The EPA funds Kargbo’s research on municipal waste ash, with collaborative assistance from the Maryland Power Plant Research Program, Columbia University and the University of New York at Stony Brook.
The Proceedings of the 18th International Conference on Solid Waste Technology and management published Kargbo’s research. The EPA presented him with a bronze medal and a certificate reading, “In appreciation of outstanding contributions to the research, technology transfer, outreach, and management of the Hazardous Research Centers Program,” at their annual awards ceremony Sept. 17.
Kargbo, originally from Sierra Leone, received his master’s and doctorate degrees in earth science from the University of Nebraska.
He became a professor at Temple in 2001 after working for the government and the EPA as a Senior Soil Scientist, and now heads Temple’s Environmental Engineering Research Group (EER).
Lindsey Walker can be reached at firstname.lastname@example.org.