The influence of sulphate on the treatment of azo dye‐containing wastewater in an anaerobic‐microaerobic compartmentalized fixed‐bed bioreactor

Abstract

A fixed bed reactor (FBR) comprised of an anaerobic zone (AZ) coupled to a micro-aerated zone (MAZ) was used for the biological treatment of synthetic textile wastewater. The azo dye in the textile effluent is expected to be reduced to aromatic amines (decolouration) in AZ followed by biological degradation of the aromatic amines due to oxygen exposure in MAZ. We focused on assessing the effect of sulphate, a common component of textile wastewaters, on the degradation of the tetra-azo dye Direct Black 22 (DB22). The influence of sulphide, a product of sulphate biological reduction, on the removal of aromatic amines, toxic by-products of DB22 degradation, was also analyzed. The