A second life for mining waste as an amendment for soil remediation

Mining is a cornerstone of the productive system, particularly in sectors, such as renewable energy and electronic equipment production, where its significance is anticipated to grow in the coming years. Aligned with the principles of Nature-Based Solutions and Zero Waste policies, recycling mining waste as soil amendments could concurrently restore degraded areas and reduce the disposal of mining waste. In this context, we aimed to remediate a post-mining soil primarily impacted by heavy metal pollution using an alkaline waste generated in dunite exploitation, either in combination with compost or independently in field conditions. The objectives were to minimize heavy metal(loid)s mobility (As, Cu, Cd, Ni, Pb, and Se), to improve soil health, and stimulate plant growth (phytoremediation, Lolium perenne L. was used). Results revealed that the combination of dunite and compost successfully reduced the concentrations of available Cu and Ni in the soil by more than four times, significantly enhanced soil properties, and promoted the harvest of a greater biomass. Additionally, Lolium perenne L. demonstrated phytostabilizing capacity for Cu and Ni in the soil treated with the amendments. In conclusion, the utilization of combined dunite-based and organic amendments proves to be a favorable strategy for restoring polluted post-mining soils.