Study on degradation of reactive brilliant red X-3B by three-dimensional biofilm electrode reactor

Abstract The treatment of azo dyes by three-dimensional biofilm electrode reactor (3D-BER) has the characteristics of fast decolorization, high mineralization efficiency and less sludge production and has broad application prospects. The 3D-BER was constructed by filling granular activated carbon (GAC) as a third bipolar electrode in the cathode chamber of conventional BER, and it greatly improved the degradation property of reactive brilliant red (RBR) X-3B. The effects of dye concentration, operating voltage, hydraulic retention time (HRT) and nitrate content on the stability of the experiment were investigated. The results reveal that azo dyes were first decomposed into aromatic amines such as aniline at the cathode, however, the amine substance was difficult to be biodegraded in the anaerobic cathode area, and then the decomposition products of aromatic amines reached the anode region and were further metabolized. Moreover, the water samples were analysed by FTIR and UV-Vis analysis. It was noted that the double bond of the azo dye was broken and degraded into aromatic amines, which were further effectively degraded.