Newswise — America's desire for cheap electricity, generated by the nation's coal-fired power plants, comes with a hidden environmental concern, says a University of Missouri-Rolla researcher.
Dr. Jianmin Wang, assistant professor of civil, architectural and environmental engineering at UMR, and his students are studying fly ash, a waste byproduct of the nation's coal-fired power plants that often ends up in landfills. In 2004 alone, the country's power plants generated more than 70 million short tons of fly ash, containing various levels of heavy metals such as arsenic, lead and mercury.
"For traditional ash, the leaching of these elements is not a significant concern," Wang explains. "However, many power plants are undergoing major renovations to meet a number of new federal regulations issued in March 2005, including the Clean Air Interstate Rule and the Clean Air Mercury Rule. These renovations will result in changes in the nature of metal binding to fly ash."
The new regulations are meant to reduce emissions of nitrogen oxide, sulfur dioxide, fine particulate matter and mercury to the air. Unfortunately, using ammonia, a common component expected to be used to reduce nitrogen oxide or particulate emissions, may actually increase the leaching of the toxic heavy metals, according to recent findings by Wang's team.
"Our research clearly indicates that high ammonia content can enhance the leaching of many heavy metals," Wang says. "In addition, more mercury could end up in fly ash as a result of the above air emission control regulations, and could be leached from the fly ash. Therefore, precaution must be taken before and during any use or disposal of fly ash that is contaminated by ammonia or activated carbon."
Research data also indicates that pH is the most significant factor affecting the leaching of arsenic and selenium from fly ash and that adding calcium could significantly reduce the leaching of arsenic. The findings could lead to the development of low-cost and environmentally friendly methods of disposal or beneficial use for fly ash.
Wang's lab is part of the newly established Environmental Research Center for Emerging Contaminants at UMR. His research is supported by the U.S. Geological Survey, Electric Power Research Institute, University of Missouri System Research Board and Anheuser-Busch Foundation.
Working with Wang on his projects are:
-- Lenin Kasthuri of Rolla, Mo., a graduate student in environmental engineering;-- Michael Dandurand of Warrensburg, Mo., a graduate student in environmental engineering;-- Harmanjit Mallhi of Jalandhar, Punjab, India, a graduate student in environmental engineering;-- Yu Liu of Weihai Shandong, China, a graduate student in environmental engineering;-- Tian Wang of Weihai, China, a Ph.D. student in civil engineering; and-- Xiaohong "Grace" Guan, a visiting scholar from Hong Kong University of Science and Technology.
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