A microbial fuel cell-coupled constructed wetland promotes degradation of azo dye decolorization products

• Further degradation of azo dye decolorization products in CW-MFC.
• The GAC in the anode promoted the further degradation of decolorization products.
• Electricity generation promoted decolorization products degradation.
• Quantitative analysis was used on the decolorization product.
• The decolorization products could degrade in the cathode of close circuit CW-MFC.

Microbial fuel cell coupled constructed wetland (CW-MFC) was constructed for azo dye decolorization and further degradation. Methyl Orange (MO) was chosen as the model azo dye due to the simple decolorization products. The decolorization products were analyzed qualitatively via GC–MS and the N,N-Dimethyl-p-phenylenediamine (DMPD) was chosen as one of the MO decolorization products to study the further degradation performance of decolorization products in the CW-MFC. 1,4-Benzenediamine, N-methyl- and p-Phenylenediamine (PPD) was another intermediate product of MO decolorization. Electrical characteristics of CW-MFC were studied to evaluate the interplay between the azo dye degradation and the electricity generation. The MO decolorization rate of open and closed-circuit CW-MFC were 75.59% and 87.60%, respectively, while the DMPD degradation rate in the anode layer of open and closed-circuit CW-MFC were 84.96% and 96.33%, respectively. In the anode layer, suitable anode materials can promote the further degradation of azo dye degradation products, while in the cathode layer, close current promoted the further degradation of the decolorization products.

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