Removal of toxic metals and anions from acid mine drainage (AMD) by electrocoagulation: The case of North Mathiatis open cast mine

The present study aims to investigate the efficiency of the electrocoagulation (EC) process on the removal of heavy metals from real acid mine drainage (AMD) samples derived from the abandoned open-cast of North Mathiatis mine (Nicosia, Cyprus). EC process was applied with the use of aluminum electrodes in 0.5 L reactors and the removal ability of several heavy metals (Fe, Zn, Mn, Cu, Ni, Cd, Cr), and anion compounds (B?, SO42?, Cl?, NO3?) detected in real AMD water was examined. The reactors agitated to avoid the mass transport over the potential of the EC reactor and different parameters such as initial pH of samples, current density (20 mA/cm2), agitation speed (600 rpm), and EC time were examined. EC process resulted in high metal removal (Fe (99,9%) > Zn (99,9%) > Mn (99,9%) > Cu (99,9%) > Ni (98%) > Cd (96%) > Cr (88%)), but with variation on-time treatment. In the case of anions, the examined process achieved also to remove B? and SO42?. Lime neutralisation was also investigated to remove the dissolved metals in AMD and to evaluate liming with the EC process. The results revealed that metal removal efficiency is dependent on the final pH achieved in the solution. Furthermore, the combination of the processes showed improvement of treatment time and removal efficiency to lime and EC process.