The Influence Of Cathode Material On The Performance And Microbial Community Of Microbial Fuel Cell

Nowadays, human society is facing serious energy challenges and environmental issues. The development of human civilization is inseparable from significant energy resource. And pollution generated by the development threatens human’s survival. The emergence of microbial fuel cell(MFC) technology provides a new method for solving energy problems and environmental pollution. MFC can transform chemical energy from wasterwater into electrical energy. By that way, MFC can purify the environment while providing green energy. Howeve r, MFC technology still has bottlenecks which hinders the application of itself, such as high cost, low efficiency and difficulties in magnification. To decline the cost, a novel method of preparing air-cathode is proposed in this article according to traditional theory and methods. Several different air-cathodes will be discussed.Base on "sandwich" air-cathode theory, AC-WBM air-cathode constructed by activated carbon, stainless steel mesh and waterproof breathable membrane for building(WBM) is designed. This air-cathode is tested in MFC systems and compared with other three kinds of air-cathodes including traditional carbon clothes cathode(Pt-CC) and two different platinum/carbon-stainless steel mesh-WBM cathode(Pt-on-SSM and Pt-on-WBM).The AC-WBM MFCs fed with 2 g/L sodium acetate as substrate reach the maximum power density of 0.96 W/m2, and the Pt-CC MFCs reach 1.30 W/m2. In consideration of the low cost of AC-WBM, the preparation method has certain research value.Then, the carbon black-PTFE mixed layer, polyethylene film(PE), and thermoplastic polyurethane films(TPU) are used to replace WBM, which constuct AC-CB, AC-PE and AC-TPU cathode. The maximum power density of AC-CB and AC-TPU are 2.15 W/m2 and 2.03 W/m2, respectively,while that of Pt-CC is 1.51 W/m2. After comprehensive evaluation, a tube reactor is constructed to test the AC-TPU that have the best overall performance.Finally, in order to explore how the different cathodes effect the microbial community of MFC system.Illumina Hi Seq platform is used to sequence the 16 S r RNA genes of biofilm on anodes and cathodes. Through results analysis, community structure of microorganisms are found to be distinct on anodes and cathodes. The dominant bacteria on anodes is Geobacter(38~75%), which belong to Proteobacteria phylum. It can be judged from microbial community structure on anodes that the enrichment of exoelectrogenic bacteria is great on anodes. The microbial community structure on the cathodes have strong link with a different type cathode. And the different types of air-cathodes has certain effects on the microbial community structure of the cathodes.