The performance of the microbial fuel cell-coupled constructed wetland system and the influence of the anode bacterial community

Abstract

ABSTRACTIn order to analyse the influences of substrate and electrode on the performance of microbial fuel cell-coupled constructed wetland (CW-MFC), the electrical generation efficiencies, the decolourization mechanism of reactive brilliant red X-3B, and the microbial communities in the anode were investigated. The closed circuit reactor fed with a mixture of X-3B and glucose (166.7 mg/L X-3B and 140 mg/L glucose) (the mixture CC reactor) got a decolourization rate of 92.79%, which was higher than the open circuit reactor (the mixture OC reactor) and the reactor fed with X-3B (the X-3B reactor). The mixture CC reactor got a maximum power density of 0.200 W/m3, which was much higher than the X-3B reactor. The intermediates produced by X-3B decolourization were further degraded in CW-MCs. The PCR-denatured gradient gel electrophoresis analysis indicated the dominance of Proteobacteria-like 16S rRNA gnen sequences. The brightest band was detected to be dominant by a Lactobacillus kefiranofaciens-like sequence. The electrogenic bacteria-associated sequences, such as Geobacter metallireducens and Desulfobulbaceae, both existed in the closed circuit and the open circuit reactors, accompanied with Desulfobacterium sp., Klebsiella sp., Aminobacter sp., Flavobacterium sp., Thauera aromatic, and Sphingomonas sp. The abundances of Geobacter sulfurreducens and Betaproteobacteria in the mixture CC reactor were 32.2% and 7.2%, respectively, and were higher than those in the mixture OC reactor. In summary, substrate and electrode can promote the performance of the CW-MFC and have effects on the microbial community in the anode of the CW-MFC.