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Use of Flue Gas Desulfurization (FGD) Gypsum as a Heavy Metal Stabilizer in Contaminated Soils
Koralegedara, N., S. Al-Abed, AND D. Dionysiou. Use of Flue Gas Desulfurization (FGD) Gypsum as a Heavy Metal Stabilizer in Contaminated Soils. Presented at 249th ACS National Meeting and Exposition, ENVR 435, Denver, CO, March 22 - 26, 2015.
Flue gas desulfurization gypsum (FGDG) has been used for many beneficial purposes such as wall board manufacturing, cement production and as an soil amendment and fertilizer in agricultural practice. Alkaline behavior, high Ca2+ and SO42- content of FGDG can be used to stabilize heavy metals in contaminated soils. However, to date there are no studies reported on use of FGDG as a heavy metal stabilizing material. The main objective of this work was to study the lead stabilizing capability of FGDG and determine the optimum conditions and lowest application rates for maximum stabilization. The results of this study will be useful in future applications of FGDG to stabilize lead contaminated soils.
Flue Gas Desulfurization (FGD) gypsum is a synthetic by-product generated from the flue gas desulfurization process in coal power plants. It has several beneficial applications such as an ingredient in cement production, wallboard production and in agricultural practice as a soil amendment due to its abundance, particle size, chemical and physical similarities to natural gypsum and the purity of the material. Due to the high Ca2+ and SO42- content and the alkaline behavior of FGD gypsum it can potentially be used to immobilize divalent heavy metals by precipitation, adsorption, cation exchange or by forming stable mineral complexes especially in soils. This study evaluates the ability of FGD gypsum to immobilize Pb in contaminated soils. Batch leaching tests were performed with soils amended with FGD. Under very acidic conditions (pH=2), 51% less Pb leaching was observed with FGD amended soils compared to un-amended soils after 48 hours. The optimum conditions to obtain maximum stabilization under different environmental conditions will be discussed.