Electrochemical degradation of a real textile wastewater using β-PbO2 and DSA® anodes

The electrochemical degradation of a real textile effluent was carried out using Ti-Pt/β-PbO2 and Ti/Ti0.7Ru0.3O2 (DSA®) anodes in a filter-press flow cell, in the presence and absence of chloride ions, varying the pH (3, 7, 11) and temperature (25 °C and 45 °C) of the effluent, and monitoring the removal of its turbidity and chemical oxygen demand (COD). The best experimental conditions for turbidity and COD removal were attained in neutral and basic conditions, independently of temperature. Higher COD removal values were attained with the Ti-Pt/β-PbO2 anode, as a consequence of its higher oxidation power; the electric charge applied per unit volume of effluent significantly decreased in the presence of chloride ions, when instantaneous current efficiencies as high as 0.5 were attained in the initial electrooxidation stages. Under these conditions, the electric energy consumption necessary to oxidize the real textile effluent was as low as 50 kW h m−3. The use of chloride ions enabled higher COD removal efficiencies using the Ti-Pt/β-PbO2 and DSA® anodes than a purely mass-transport controlled process due to indirect oxidation processes mediated by the active chloro species.