Innovative Biohydrometallurgical Processes for Decontamination of Acid Mine Drainage

The main aim of this experimental work is to investigate remediation biohydrometallurgical processes for toxic metals removal (Zn, Cu, Mn, Al and Fe) from Acid Mine Drainage (AMD), recovering purified useful metals. The main cause of river water pollution in Western and Central European regions (Albania, Kosovo, FYR of Macedonia, Slovakia, Romania) and in South America regions (Perù, Bolivia, Argentina, Brasile....) is undoubtedly represented by metal sulphide (copper, zinc, iron, SO4 etc.) ore deposits and tailings abandoned near to closed and/or open mines. The aim of environmental protection policy of the region is devoted to the reduction of the content of heavy metals in the rivers. Water drainages have an appreciable metal content over the permitted standard. The metals of primary concern are Cu, Cr, Fe, Al, Mn, Hg, Ni, Pb, As and Zn. The processes studied are innovative, intended to reaching a specific purpose, economically and environmentally. These could be integrated with physical treatments, with the dual aim of reducing pollution of inland waters at the same time producing useful metals (copper, nickel, zinc, etc.). The benefit for the environment will result in the reduction of toxic effects on living organisms. Biohydrometallurgical applications - constituted by bioprecipitation/electrowinning - have demonstrated the technical feasibility of the process aimed at the removal of toxic metals from AMD samples; in fact, at the end of the process, the metals' concentration decreased under the recommended legislation limit, achieving metals at high degree of purity (about 95%).