An integrated approach for enhanced textile dye degradation by pre-treatment combined biodegradation

The wastewater released by the textile industries affects aquatic, plant and human life. Though there are many conventional wastewater treatment techniques, interest on coupled treatment methods has increased in the recent times owing to their increased efficiency. In the present study, the textile wastewater was pre-treated by three different techniques, viz. sonication, photocatalysis and ozonation. Increasing the treatment time increased the biological oxygen demand to chemical oxygen demand (BOD/COD) ratio, and thus the biodegradability was about 0.6–0.73. Effluent pre-treated by photocatalysis showed relatively higher biodegradability compared to ozonation and sonication. The degradation of aromatic compounds due to pre-treatment was substantiated by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (¹H NMR) spectroscopy. Since pre-treatment increased the biodegradability of the effluents, further biological degradation using acclimatized sludge biomass resulted in COD removal efficiencies 94, 91 and 82 %, respectively, for photocatalysis, sonication and ozonation. The morphology of the organisms which played a major role during the degradation of pre-treated effluent was examined under scanning electron microscope (SEM).