Degradation of azo dye wastewater by the combination process of 3D BER and CW-MFC

Abstract

The treatment of azo dye wastewater has become a hot issue in the area of water pollution control. In this paper, a novel combined process of constructed wetland-microbial fuel cell (CW-MFC) and three dimensional biofilm electrode reactor (3D BER) was carried out for treatment of reactive brilliant red X-3B dye wastewater. Decolorization rate, COD removal and electricity generation in the combination process were studied, and the main factors affecting the system’s performance were also investigated. The results showed that the decolorization rate of combination process (3D BER-CW-MFC) was over 96%, and closed-circuit CW-MFC had better decolorization effect than open-circuit CW-MFC. COD removal rate of the combination process was far higher than the 3D BER and CW-MFC operated alone (78.9%∼90.8% and 50.6%∼66.2%, respectively). With the increase of influent dye concentration in the 3D BER, Cell voltages of the CW-MFCs all increased firstly and then decreased. The cell voltage reached the maximum at influent dye concentration of 600 mg L-1, and then decreased by 6.42%∼14.34% after the dye concentration increased to 1000 mg L-1. In addition, cell voltage could be enhanced by increasing the cathode area of CW-MFCs, due to improved cathode potential and reduced total internal resistance of the system.