Nickel removal from simulated wastewater using a novel bio-electrochemical cell with packed bed rotating cylinder cathode

Abstract

In the present study, a microbial electrolysis cell (MEC) with a new design using a packed bed rotating cathode was examined for the removal of nickel from simulated wastewater. Effects of the applied voltage, the initial nickel concentration in the catholyte, the catholyte's initial pH, and the cathode's rotation speed were investigated. Results showed that nickel removal efficiency increased with increasing the applied voltage, decreasing the initial concentration of nickel, increasing the pH up to 6, and increasing the rotation speed up to 400 rpm. Many different behaviors of concentration decay with time for packed bed rotating cathode and smooth cylinder rotating cathode were observed. The concentration profile was approximately linear in the case of a smooth rotating electrode and an exponential decay concerning the packed bed electrode. The best-operating conditions were an applied voltage of 1.1 V, an initial nickel concentration of 100 ppm, an initial pH of 6, and a rotation speed of 300 rpm in which a removal efficiency of 99.7% was obtained with an energy consumption of 0.88 kWh/kg Ni that is lower than the energy required for removal of nickel by the conventional electrolysis method. These results demonstrate that the MEC with the new design can be an alternative process to effectively remove Ni from wastewater at lower cost and high efficiency.