Minespoil amendment with dry flue gas desulfurization by-products: Plant growth

One potential use for alkaline, dry flue gas desulfurization (FGD) by- products is in reclamation of acidic minespoils. Greenhouse column studies of 8-mo duration investigated growth and tissue composition of plants grown on three acidic minespoils amended with two dry FGD by-products (lime injection multistage burners, LIMB; and, pressurized fluidized bed combustion, pFBC). Amendment amounts ranged from 0 to 320 g kg^-1 by dry weight. Two minespoils also were amended with sewage sludge at 60 g kg^-1 by dry weight. Column mixes were planted with Kentucky 31 tall fescue (Festuca arundinacea Schreb.). After 92 d of growth, fescue was harvested every 30 d for a total of six harvests. Tissue composition was determined on material from the sixth harvest. Root growth was measured at the end of the experiment. Fescue growth was improved by FGD amendments of 30 to 120 g kg^-1, but larger amendments caused high pH and cementation, which decreased rescue growth and limited rooting volume. Plant tissue composition was generally within sufficiency ranges for the elements analyzed. Tissue Ca, Mg, and S were increased by FGD amendment, while tissue concentrations of most trace elements were decreed. There was no increase in tissue B from PFBC, however, LIMB application caused B concentrations >100 mg kg^-1, which could be toxic to less tolerant species. These results indicate that when applied in amounts equivalent to spoil neutralization needs, dry FGD by-products can benefit acidic spoil revegetation with little potential for introduction of toxic elements into the food chain.