摘要
Over 16 million metric tons of flue gas desulfurization (FGD) gypsum are produced every year, with roughly half of this material being disposed of in landfills. While the beneficial utilization of synthetic FGD gypsum reduces consumption of natural resources and energy, there is concern about the potential release of trace elements in some applications. In this paper, we examine the release of inorganic constituents from FGD gypsum under a variety of management scenarios. Cumulative, 100-year release estimates based on either percolation- or diffusion-controlled scenarios were low; significantly lower in fact than estimates based on TCLP or SPLP methodologies, suggesting that the TCLP and SPLP methods are overly conservative in estimating the environmental impact of FGD gypsum utilization evaluated in this study. Percent cumulative release of elements from FGD gypsum in fill applications decreased with decreasing infiltration and increasing fill depth in percolation-controlled scenarios. Therefore, increasing the fill depth reduces cumulative percent release of elements due to the saturation of the pore fluid thereby inhibiting further dissolution. Decreasing pH influenced the release of some elements in FGD gypsum, notably Be, Cd, Mg, Mn, Ni, Si and Zn. The results from this research provide important new information for evaluating the leaching potential of synthetic FGD gypsum in a variety of management scenarios.