Two-Phase Partitioning Bioreactors Applied to Colour Removal from Real Textile Wastewater

In this paper, we propose the application of a solid-liquid Two-Phase Partitioning Bioreactor (TPPB) to colour removal (reactive azo-dyes) from a real textile wastewater. Polymer screening was performed in the pH range of 4-9 to select the most effective absorptive polymer to be used as the partitioning phase in the TPPB. Four polymers were tested and the best results were obtained with Hytrel 8206 at pH 4 obtaining ~70% colour removal (when referred to the dominant wavelength) in the first 5 hours of contact time. The biological process was undertaken in a solid-liquid TPPB operated with Hytrel 8206 in sequential anaerobic-aerobic mode. The reaction time of 23 hours was equally distributed between anaerobic and aerobic phases and, to favour colour uptake, the pH was controlled at 4.5 in the first 4 hours of the anaerobic phase, and then increased to 7.5. Colour removal efficiencies increased from 70 to 85% by modifying the bioreactor operation from single phase to TPPB mode.