The impact of electrode corrosion behaviour, reactor geometry and current density on electrocoagulation efficiency were investigated for the treatment of molasses process wastewater. Two laboratory-scale vertical plate electrocoagulation reactors were used for this investigation: the first being a low aspect ratio bath reactor with a low specific electrode area, while the other was a high aspect ratio column reactor with a high specific electrode area. Anomalous anodic dissolution and cathodic corrosion of the aluminium electrodes both contributed significantly to overall metal consumption. Increasing specific electrode area and aspect ratio each led to improved treatment efficiency, whereas the impact of current density was more complicated involving the combined influences of several competing effects. The space-time yields of coagulant and bubbles (both functions of specific electrode area, current density and current efficiency) were found to influence mixing within the reactor and thus treatment efficiency.
Keywords: current efficiency, electrocoagulation, melanoidins, molasses process wastewater, reactor design, residence time distribution