Biotransformation of disperse blue 79 by an anaerobic sequencing batch biofilter

The mineralization of the azo dye Disperse Blue 79 (DB79) was studied under sequenced anaerobic/aerobic environments. This paper presents the results of the first stage of the process, i.e., the anaerobic decolouration of the azo dye. A sequencing batch biofilter was used. The results showed that DB79 was only biotransformed to amines, resulting in a decolorization of the effluent. The anaerobic bacteria, without using co-substrate, achieved the decolouration when the concentration of DB79 was lower than 48 mg/l. It was necessary to use a co-substrate to reach decolouration efficiencies higher than 95%, when the concentration of DB79 in the influent was superior to 48 mg/l. In 72 h more than 95% of the initial colourant was biotransformed.