Heavy metal recovery combined with H₂ production from artificial acid mine drainage using the microbial electrolysis cell

The aim of this study was to utilize the microbial electrolysis cell (MEC) for metal removal from acid mine drainage (AMD) and simultaneous H2 production. A dual-chamber MEC was developed to concurrently produce H2 and remove Cu(2+), Ni(2+), and Fe(2+) from AMD under single and mixed metal conditions. With an applied voltage of 1.0V, Cu(2+) in the AMD was prior to others to be recovered at the cathode, followed by Ni(2+), and finally Fe(2+). The H2 production rates achieved during the AMD treatment were in the range of 0.4-1.1m(3)m(-3)d(-1), and the highest rate was obtained with the AMD containing single Cu(2+). The highest efficiency of cathode electron recovery reached 89%, which was obtained with the AMD containing mixed metals. The recovered electrons were used for both H2 production and metal reduction. The energy recovery efficiency of MEC reached up to 100%, suggesting that H2 generated from AMD was sufficient to offset the energy input during the treatment. The MEC was successfully applied to remove metals from the AMD, recover value-added products of Cu(0) and Ni(0), and to produce H2.