Successful application of electrocoagulation technology requires a thorough evaluation of electrode behaviour. This study is concerned with the treatment of fermentation wastewater, generated by molasses-fed biorefineries in large volumes and containing high concentrations of biorecalcitrant, coloured organic melanoidins that form a highly dispersed colloid. The polarisation behaviour, surface morphology and current efficiency of both hot rolled coil steel and 5005 aluminium electrodes were investigated. The steel electrodes were found to be susceptible to aggressive anodic pitting which is attributed to the high chloride content of the wastewater, while the aluminium exhibited anomalous corrosion of the anode and cathode. The redox potential of the wastewater has a significant effect on Fe2+/Fe3+ speciation with steel electrodes and thus on the decolourising efficiency of electrocoagulation. The practical implications of the corrosion characteristics are discussed.
Electrocoagulation Current efficiency Cyclic voltammetry Iron speciation Fermentation wastewater