Cobalt Removal from Simulated Wastewaters Using a Novel Flow-by Fixed Bed Bio-electrochemical Reactor

Abstract

In this study, the performance of a new design of flow-by fixed bed bio-electrochemical reactor was investigated for cobalt removal from simulated wastewater. The influence of operation parameters such as applied cell potential, initial cobalt concentration, pH of the catholyte, and the mesh size of the cathode on the performance of the bio-electrochemical reactor were investigated. The results showed that the applied cell potential had the largest effect on cobalt removal efficiency. An increased cell potential resulted in an increase in removal efficiency, while an increased initial cobalt concentration led to a decrease in removal efficiency. The results confirmed that using a pH < 3 caused a sharp decrease in removal efficiency while a pH > 7 led to a slightly decrease in removal efficiency. Using a mesh no. > 30 gave a lower removal efficiency. The best operating conditions were a cell potential of 1.8 V, an initial cobalt concentration of 50 ppm, and a pH of 7. Under these conditions with a stack of stainless no. 30 steel mesh as a packed bed cathode, a removal efficiency > 99% was obtained, in which the final cobalt concentration was reduced to < 1 ppm at 100% current efficiency and a low energy consumption of 1.564 kW h/kg cobalt.