| Sediment Microbial Fuel cells（SMFC）,as devices capable of simultaneously delivering energy and bioreactor,can use microorganisms to degrade environmental pollutants and convert chemical energy directly into electrical energy.As the carrier of electric-generating microorganisms,anode material can affect the microbial community structure on its surface to a certain extent,thus affecting the battery performance.Therefore,the internal relationship between different anodes and their surface microbial communities can provide a theoretical basis for optimizing the performance of SMFC system at microbial level.In this paper,the operation characteristics and microbial community structure of conductive polymer（polypyrrole,polyaniline,polythiophene）modified electrode,metal oxide（manganese dioxide,nickel oxide,tricobalt tetraoxide）modified electrode and composite modified electrode（polypyrrole@tricobalt tetraoxide）in SMFC were studied.The main research results are as follows:Firstly,polypyrrole,polythiophene and polyaniline modified graphite plate electrodes were prepared by constant-current deposition method.The maximum output power densities of SMFC constructed with three conductive polymer modified electrode anodes are 221.36m W/m2,212.74 m W/m2 and 209.36 m W/m2,respectively.Compared with blank graphite plate（127.61 m W/m2）,the maximum output power density of polypyrrole modified electrode is increased by 73.47%,showing the best performance of electricity generation and long-term stability.The high-throughput sequencing results showed that there were significant differences in the electric-generating microbial community structure on different anode surfaces after electrode orientation selection.Desulfobacterota is gradually replacing Firmicutes that dominate the original sediment at gate level,with the highest relative abundance of 61.52 percent on the surface of poly-pyrrole modified electrode.Desulfobulbus,Desulfocapsa and Sulfurovum are predominant on different anode surfaces at the genus level.The above results showed that the modification of conductive polymer significantly improved the electrical performance of the battery,and promoted the differentiation of the microbial community structure on the anode surface,and the proportion of electric-producing bacteria increased significantly.Then,tricobalt tetraoxide,manganese dioxide and nickel oxide modified graphite plate electrodes were prepared by constant-current deposition method.The maximum output power densities of SMFC constructed with three metal oxide modified electrode anodes are 219.43m W/m2,200.21 m W/m2 and 194.88 m W/m2,respectively.Compared with the blank graphite plate,the maximum output power density of the tricobalt tetraoxide modified electrode is increased by 71.95%,and the electricity generation performance is excellent and the long-term operation is more stable.High throughput sequencing results showed that the tricobalt tetraoxide group and manganese dioxide group had more similar community structure,but the difference was larger than that of nickel oxide group.Under the phylum level,Firmicutes is replaced by Desulfobacterota in the original sediment with a final relative abundance of 35.27%（Co3O4）,34.31%（Mn O2）and 49.3%（Ni O）,respectively.At the genus level,Sulfurovum,Desulfobulbus and Desulfocapsa are all significantly enriched,and metal-tolerant bacteria such as Pseudomonas,Bacteroides and Faecalibacterium have emerged.The above results showed that the modification of metal oxides also significantly improved the electrical performance of SMFC,and promoted the differentiation of the microbial community structure on the anode surface,the proportion of electric-producing bacteria increased significantly.In addition,more metal-tolerant bacteria were developed in the electrode surface biofilm.Finally,the PPy@Co3O4 composite modified electrode with three-dimensional grid structure was prepared by constant-current deposition method.The maximum output power density of the constructed SMFC reached 247.86 m W/m2,which was 94.26%higher than that of the blank control group.High throughput sequencing results showed that the community structure of composite modified anode was significantly different from that of single modified anode.At phylum level,Campilobacterota and Desulfobacterota have become the predominant phylum in place of Firmicutes,with similar percentages of relative abundance,22.58%and 21.47%,respectively.Desulfobulbus and Sulfurovum are predominant electricity-producing microorganisms in the biofilm at the genus level,with concentration of Streptococcus,a fermentation functional bacterium,observed,with a final relative abundance of 2.68 percent.In addition,the changes of sulfur and heavy metal contents near the composite modified anode were also monitored.The results showed that the sulfur removal rate of composite anode SMFC was 65.49%after 45 days of operation.The adsorption capacity of Cr,Cu,Mn and Fe on the anode surface increased to varying degrees.This shows the potential of SMFC in the direction of sediment bioremediation and has certain value for practical engineering applications. |
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