Electrochemical treatment of tannery wastewater using Ti/Pt and Ti/Pt/Ir electrodes

The treatment of tannery wastewater by the electrochemical method using Ti/Pt and Ti/Pt/Ir electrodes is investigated. The aim of a satisfactory elimination of NH+4 from wastewaters of different strength was achieved using both types of electrodes. A Ti/Pt/Ir anode proved to have the electrocatalytical properties for NH+4 removal, but it resulted to be more sensitive to poisoning by H2S contained in the wastewater. For both types of the electrodes NH+4 removal followed pseudo-first order kinetics, with the rate decreasing in function of the presence of organic substances. A concurrent removal of COD was observed particularly with a Ti/Pt anode, but its magnitude was not sufficient to ensure the discharge limits to be met while treating the raw wastewater only by the electrochemical process. In conclusion the electrochemical process can be applied successfully as a final polishing or an alternative to biological nitrification, but cannot substitute completely the traditional treatment of tannery wastewater.