Coupling of electrodialysis and bio‐electrochemical systems for metal and energy recovery from acid mine drainage
Yelitza Delgado, Javier Llanos, F.J. Fernández
Abstract
Abstract BACKGROUND This work studied the treatment of a synthetic sphalerite acid mine drainage (AMD). The treatment was carried out by means of a previous concentration stage using electrodialysis, followed by electrodeposition using a bioelectrochemical system (BES). RESULTS The best concentration results were obtained when operating the electrodialysis at 8 V and at a diluate/concentrate volume ratio of 3. This treatment yielded a concentrate fraction of about 25% of the volume and a clear fraction of about 75% of the volume. The concentrated fraction was treated in a BES for the electrodeposition of the metal contained. By operating a microbial fuel cell (MFC), the spontaneous reactions took place and, in 2 days, all the Fe 3+ was reduced to Fe 2+ ; then, all the Cu 2+ was electrodeposited as pure Cu 0 in about 8 days. The maximum current density attained in this stage was 0.1 mA cm −2 and the maximum power was 0.05 W cm −2 . Then, a subsequent operation of a microbial electrolysis cell (MEC) allowed for the simultaneous recovery of the Fe 2+ , Ni 2+ , Zn 2+ , and Cd 2+ as a mixed metal mass. CONCLUSION The electrodialysis yielded a clear effluent representing 75% of the total volume and a concentrated effluent accounting for 25%. It was possible to treat the concentrated effluent in an MFC, recovering pure Cu 0 with a net electricity generation. The non‐spontaneous metal reductions were subsequently accomplished by means of MEC, the electricity requirements being lower than those in the case of the raw AMD due to the higher mass transfer rate and the reduction of the Ohmic loses. © 2023 Society of Chemical Industry (SCI).