Anaerobic/aerobic treatment of colorants present in textile effluents

The operation of an anaerobic/aerobic process used to degrade the colorants present in textile wastewater is presented. The objective is to produce water that can be reused. Two particular cases were studied: the degradation of a synthetic wastewater containing the colorant disperse blue 79 (DB79) as a model compound and a real textile effluent containing reactive azo dyes. The biodegradation was achieved using a single tank operated as sequencing batch reactor. It was observed that the DB79 was biotransformed to amines in the anaerobic stage decolorizing the wastewater. The amines formed were subsequently mineralized in the aerobic phase. An increase of toxicity was observed in the anaerobic stage due to the amines formation, but the wastewater was detoxified after the aerobic treatment. Removal efficiencies of DB79 around 92% were observed after the treatment. Around 96% of the initial color of the real wastewater was effectively removed. It was observed that the biomass pre-acclimatized to the degradation of DB79 was more effective for the color removal than a freshly inoculum used.