RESOURCE FROM RECOVERY FGD GYPSUM: ADDRESSING ENVIRONMENTAL RISKS OF HAZARDOUS TRACE ELEMENTS FOR SAFER REUSE

Flue gas desulfurization (FGD) gypsum, a by-product of coal-fired power plants, offers potential for recycling, particularly in the construction industry and agricultural applications. Its abundant availability and favorable physical properties make it an attractive alternative to natural gypsum. However, the presence of hazardous trace elements (HTEs) such as arsenic (As), cadmium (Cd), chromium (Cr), and zinc (Zn) can pose significant challenges for safe reuse. These elements may leach into the environment, especially under certain chemical or physical conditions, leading to contamination of soil and groundwater. This study explores the speciation and leaching behavior of ten HTEs (As, Cd, Cr, Pb, Cu, Ni, V, Zn, Sb, and Co) in FGD gypsum samples collected from power plants in Serbia, aiming to inform strategies for safer recycling and more sustainable waste management. The results indicate that certain elements, notably As, Cd, and Cr, exist in forms that are highly soluble and bioavailable, suggesting a considerable risk of leaching during use, storage, or landfilling. For instance, As is found in easily soluble fractions in concentrations ranging from 19.8% to 32.5%, while Cr shows a particularly high proportion (70.6%–91.3%) in fractions susceptible to release under environmental conditions. Cd also exhibits a high share in soluble form (31.3%–49.4%), further increasing its environmental mobility. While overall leaching tests suggest that FGD gypsum can be classified as non-hazardous waste, the variability in the mobility of individual elements highlights the importance of targeted risk management. Elements such as Cd, As, and Cr fall within medium to high environmental risk categories and require careful monitoring in any recycling or reuse context.