Research On Microbial Characteristics Of Microbial Fuel Cell Coupled With Constructed Wetland

In the paper, a microbial fuel cell coupled with constructed wetland (CW-MFC) was built as the reactor. The facters which have an effect on the system’s electrical performance, the performance of the CW-MFC on refractory organics degradation and simultaneous electricity generation, the anode microbial community structure and the degradation path of Methyl Orange (MO) was analyzed.Different electrode spacing in three different volume reactors was set to research the influence of volume and electrode spacing on the system’s electrical performance, especially the internal resistance (Rint). The result showed that the voltage decreased with the reduced volume, and the Rint and ohmic resistance (RΩ) increased with the expanded electrode spacing. Elevation of phosphate buffer (PB) concentration could significantly reduce Rint and RΩ. The reactor with 50mM PB got the best electrical performance. The CW-MFC with ceramic bead as filler got the better electrical performance than the one with glass bead. The larger filler size could reduce the Rint. The reactor with 1～2cm diameter gravel as filler got the largest maximum power density (Pmax).Reactors with different co-substrate concentration and open/closed circuit condition were set, found that co-substrate was necessary to CW-MFC and electrode effect can stimulate the azo dye decolorization. The lower filler layer could assist the system with its degradation and electrical performance.The anode bacterial 16S rRNA sequences were present with the Proteobacteria-like as the dominant. The sequences which similar to electrogenic bacteria Geobacter metallireducens and Desulfobulbaceae, both existed in the closed circuit system and the open circuit system. The degradation bacteria-like sequences, which similar to Desulfobacterium sp., Klebsiella sp., Aminobacter sp., Flavobacterium sp., Thauera aromatic, and Sphingomonas sp., were also detected. The densities of G. sulfurreducens and Betaproteobacteria in the closed circuit system were 35.29% and 5.88% higher than that of the open circuit system, respectively.Intermediates in MO degradation were detected by GC-MS, such as N, N-Dimethyl-p-phenylenediamine (DMPD), N-methyl-p-Phenylenediamine and 1, 4-Benzenediamine (PPD). N-methyl-p-Phenylenediamine and PPD were the degradation products of DMPD. The electrode effect accelerated the reduction of DPMD.