Leachate phytotoxicity of flue gas desulfurization residues from coal-fired power plant

Abstract

Flue gas desulfurization residues (FGDR) are the main solid wastes produced in coal-fired power plants that can be reused as alternative materials for civil and agricultural applications. However, the pollutants contained in the FGDR might contaminate the local environment, hindering their material reuse. In this study, the physical-chemical characteristics, leaching, and phytotoxicity (Triticum aestivum) of the material were investigated. The FGDR samples were obtained from three pulverized coal-fired power plants in China. Multivariate statistical analyses were used to consider the contributions of the leaching components to the germination index of wheat seeds in the FGDR leachates. The FGDR contained a high percentage of amorphous mass. The ranges of selected metals and micronutrients in the FGDR are As (31.5–63.0 mg/kg), B (574–3090 mg/kg), Ba (2799–3073 mg/kg), Cr (up to 4.73 mg/kg), Cu (0.29–1.38 mg/kg), Mn (136–370 mg/kg), Ni (9.93–22.9 mg/kg), Pb (1.29–7.29 mg/kg), Sr (886–1706 mg/kg), and Zn (335–458 mg/kg). The leaching toxicity of the FGDR leachates was lower than the regulatory limit of the identification standards for hazardous waste, indicating that the FGDR are non-hazardous materials. Metals, especially Ba, Cu, Fe, and Pb, as well as As and B, in the leachate had inhibitory effects on seed germination than the other constituents. The results in this study showed that the leachate phytotoxicity resulting from FGDR could be evaluated before the utilization of FGDR, giving crucial information for the adaptation of these alternative materials.