Sustainable Ecological Restoration of Sterile Dumps Using Robinia pseudoacacia

The feasibility of using Robinia pseudoacacia in phytoremediation of sterile dumps was determined. The potential of Robinia pseudoacacia seeds to grow in a medium contaminated with high concentrations of Pb, Cd, and Cu was firstly evaluated by applying germination tests on acacia seeds in the presence of various extractants prepared by mixtures of sterile material (SM) collected from the "Rades" dump (Romania), calcium carbonate (CaCO3) and dehydrated sludge (DS) from Somes Water Treatment Plant (Cluj Napoca, Romania), fertilizer (N.P.K.), and potassium monobasic phosphate (KH2PO4-99.5%). The results indicated that Robinia pseudoacacia seeds grow much better in an acidic than in a neutral medium and in the absence of carbonates. The capacity of metal uptake from SM by Robinia pseudoacacia and the development of the plants were then investigated at the laboratory scale. During the phytoremediation process, 92.31% of Cu was removed from SM, and the development of the Robinia pseudoacacia plants was favorable. However, although the results of the present study indicated that Robinia pseudoacacia can be successfully used in the phytoremediation of sterile dumps, making a sustainable decision for the current situation of sterile dumps located in mining areas may be difficult because an optimal point between people, profit, planet, and diverse ethical views must be found.