Emission and Leaching Potential of Mercury from Flue Gas Desulfurization (FGD) Byproducts Amended Soil

The release of mercury (Hg) into atmosphere, infiltration, and uptake by plants from flue gas desulfurization (FGD) material-amended soils was studied. The project was carried out in three phases: (1) laboratory study, (2) field study, and (3) life cycle calculation. In the laboratory study, factors controlling the release of Hg from FGD by-product amended soil were investigated under well-controlled greenhouse environment. The field investigation was carried out based on results obtained from laboratory greenhouse studies. Life cycle analysis was carried out to calculate the release of Hg from the FGD material-treated soils under a conceptive model to evaluate the environmental impacts associated with the additions the three FGD materials used in this study. Introduction The production of flue gas desulfurization (FGD) by-products (especially synthesized gypsum) is expected to increase in response to the tightening emission regulations for coal-fired power industry. With the declining demand of FGD gypsum for wallboard production, alternatives to landfill are needed. Soil amendment is a potential mass application for FGD gypsum. It has been reported that FGD material amendment, although increased the tissue concentration of trace elements (e.g., arsenic, selenium, and boron), did increase the plants grown without significant adverse effect on soil and leachate quality. In these studies, the environmental impact associated with the FGD land application was evaluated by the concentration levels of trace elements (e.g., arsenic, selenium, boron, and molybdenum) in the soil, soil lechate, and plant tissues. However, the information on the release of mercury from the FGD material-amended soil has been lacking. It is expected that more mercury or other trace elements will present in the FGD by-products under the implementation of federal and/or state 2009 World of Coal Ash (WOCA) Conference May 4-7, 2009 in Lexington, KY, USA http://www.flyash.info/