Removal of Real Textile Dyes by Electrocoagulation/Electroflotation in a Pilot External-Loop Airlift Reactor

Abstract

This paper studied the efficiency of electrocoagulation/electroflotation in removing colour from real textile wastewater by using aluminum and iron electrodes in an innovative pilot external-loop airlift reactor of 150 L. The reactor was designed to operate in batch and continuous modes. The real effluent contained 90% of disperse dye and 10% of reactive dye. A complete flotation of pollutants with acceptable mixing was achieved in this reactor using only the overall liquid recirculation induced by H2 microbubbles. The treatment of these discharges was easier using electrodes of iron rather than aluminum. The optimal initial pH was 10 for both aluminum and iron electrodes. By using iron electrodes, the maximum decolourisation efficiency and COD reduction efficiency reached respectively 96% and 65% for 90 minutes of treatment. Similarly, by using aluminum electrodes, the maximum decolourisation efficiency reached 90%, COD reduction reached 51% for 120 minutes of treatment. In the case of an initial pH slightly different to 10, the required time to reach 90% ranged from double to triple.