Anaerobic transformation of Cationic Red X-GRL with low levels of carbon source

•Both color and aromatic amines can be removed with low carbon source.•Sucrose, EPS and aromatic amines play role in decolorization.•Role of bacteria and archaea in X-GRL biotransformation was investigated.•X-GRL improve the degradation of aromatic amines.

In this study, an anaerobic upflow biological filter (UBF) was used for the treatment of Cationic Red X-GRL (X-GRL)-containing wastewater with low concentrations of carbon sucrose. The performance and mechanisms involved in the color removal and aromatic amine transformation under anaerobic condition were investigated. The results showed that all color and more than 90% of aromatic compounds were removed by UBF with 200 mg/L of X-GRL and 50 mg/L of sucrose in the influent, which indicates the UBF is effective for degrading X-GRL with a low concentration of carbon source. The sucrose acted as an initial electron donor for X-GRL reduction, and the EPS and aromatic compounds also donated electrons for the cleavage of azo bond, leading to decolorization of X-GRL. The addition of X-GRL improved the anaerobic degradation of a