Use of electrochemical oxidation process as post-treatment for the effluents of a UASB reactor treating cellulose pulp mill wastewater

The main purpose of this study was to evaluate the performance of the electrochemical oxidation process as a post-treatment for the effluents of a bench-scale UASB reactor treating simulated wastewater from an unbleached pulp plant. The oxidation process was performed using a single compartment cell with two plates as electrodes. The anode was made of Ti/Ru_0.3Ti_0.7O₂ and the cathode of stainless steel. The following variables were evaluated: current density (75, 150 and 225 mA cm⁻²) and recirculation flow rate in the electrochemical cell (0.22, 0.45 and 0.90 L h⁻¹). The increase in current density from 75 to 225 mA cm⁻² did not increased the color removal efficiency for the tested flow rates, 0.22, 0.45 and 0.90 L h⁻¹, however the energy consumption increased significantly. The results indicated the technical feasibility of the electrochemical treatment as post-treatment for UASB reactors treating wastewaters from pulp and paper plants.