Acid mine drainage treatment and sequential metal recovery by means of bioelectrochemical technology
Luis Fernando León‐Fernandez, Hassay Lizeth Medina‐Díaz, O. González Pérez, Luis Rodríguez Romero, José Villaseñor, F.J. Fernández
Abstract
Abstract BACKGROUND This work studied the treatment of and metal recovery from a synthetic acid mine drainage (AMD) containing 500 mg L −1 copper (Cu 2+ ) and iron (Fe +3 ), and 50 mg L −1 nickel (Ni 2+ ) and tin (Sn 2+ ) by using a bioelectrochemical system (BES). The presence of electroactive bacteria improved the performance of such reactor configuration, by contrast with systems with abiotic anodes. RESULTS Operating as a microbial fuel cell (MFC), all of the Fe 3+ was reduced to Fe 2+ in about 24 h and Cu 2+ was electrodeposited onto the cathodic surface, a Cu electrode, obtaining pure Cu 0 . Almost all of the Cu in the catholyte was recovered after four days. The maximum current density and power attained in this stage were 0.136 mA cm −2 and 0.0134 mW cm −2 , respectively. Subsequent operation as a microbial electrolysis cell (MEC) allowed simultaneous recovery of the Fe 2+ , Ni 2+ and Sn 2+ by fixing the cathode potential at −0.7 V versus Ag/AgCl. The electrode material in this stage was titanium. The tin was completely deposited onto the cathodic surface after one day of electrolysis. After three days, 77% and 60% of Ni and Fe, respectively, was recovered. CONCLUSION It was possible to recover Cu 0 while generating electricity at the same time using a BES. The cell voltage required for the metal electrodeposition of Fe 2+ , Ni 2+ and Sn 2+ was low in the case of the BES because of the contribution of the electroactive bacteria. Sequential metal deposition is possible by adjusting the operating parameters of the BES reactors. © 2021 Society of Chemical Industry