The Efficiency And Mechanism Of Microbial Fuel Cell Based On Species Interaction For Protein-rich Sewage Treatment

Microbial fuel cell（MFC）is a device that directly converts the chemical energy in organic matter into electrical energy using electroactive microorganisms as anodic catalysts.It has broad application prospects in the fields of wastewater treatment and new energy development.In MFC,electroactive bacteria interact with other microbial populations through intermediate metabolites,forming a complex metabolic network that is an important factor affecting the performance of MFC.MFC can overcome the bottleneck of slow protein degradation and utilization in anaerobic fermentation processes,and efficiently convert protein-rich organic wastewater into electricity.However,the microbial mechanism of this process is still unclear.Therefore,elucidating the process and mechanism by which Proteiniphilum acetatigenes TB107^Tand Geobacter sulfurreducens PCA co-culture systems convert protein to electrons through population interactions is of great scientific significance for the utilization of MFC in the treatment of protein-rich wastewater.Based on this,this paper investigates the operating performance of mixed-culture MFCs under different substrate concentrations and salt concentrations,examines the degradation of protein and hydrogen production capabilities of co-culture system MFCs,obtains the metabolic characteristics of microbial populations under different salt conditions using untargeted metabolomics technology,and discusses the degradation mechanism of P.acetatigenes and G.sulfurreducens for high-salt protein wastewater through differential metabolites and metabolic pathway analysis.The enhanced treatment efficiency of co-cultured bacterial communities for kitchen wastewater is also examined.The main conclusions are as follows:（1）The performance of the microbial fuel cell（MFC）with different protein substrate concentrations was investigated.The closed circuit TB107^T&PCA reactor achieved the highest biomass and protein degradation rate at concentration C₂（45 m M）,which were 0.91and 48.53%,respectively.These values were 8.60%and 9.50%higher than those of the open circuit TB107^T&PCA reactor and 1.70 times and 1.53 times those of the control group TB107^Treactor.The results indicated that MFC enhanced the protein degradation ability of the co-culture system.Moreover,the closed circuit TB107^T&PCA reactor achieved the highest power density（507.64 m W/m²）and voltage（275.25 m V）at concentration C₂（45m M）,with a maximum power density 1.45 times that of concentration C₁（35 m M）and 1.42times that of concentration C₃（65 m M）.The MFC system also achieved the highest COD removal rate（43.28%）at a substrate concentration of 45 m M.（2）The treatment efficiency of MFC under different salinity concentrations was compared.The 100m M salinity TB107^T&PCA reactor obtained the highest biomass and protein degradation rates,0.82%and 53.38%,respectively,which were 29%and 14.8%higher than the control TB107^T&PCA reactor.The results showed that 100m M salinity promoted the protein degradation ability of the coculture system.At the same time,the 100m M salinity TB107^T&PCA reactor achieved the highest power density（557.23 m W/m²）,the highest voltage（205.07 m V）,and the highest COD removal rate（42.53%）.Untargeted metabolomics studies found that 22 metabolites were significantly downregulated and 55metabolites were significantly upregulated in the 100 m M saline group compared to the 0m M saline group on the third day of the reaction;Among them,ABC transporters,purine metabolism,aminoacyl t RNA biosynthesis,and nucleotide metabolism are the four most significant metabolic pathways,with the main differentially involved metabolites being valine,adenosine,L-histidine,DL-lysine,and hydroxyproline.Compared with the 200 m M group,the 100 m M group had 14 metabolites that were significantly downregulated and 55metabolites that were significantly upregulated.The p-value of purine metabolism,mineral metabolism,nucleotide metabolism,and ABC transporters was the lowest,indicating that the expression intensity of these four metabolic pathways in MFC was significant.On the 6th day,compared with the 0 m M group and the 100 m M group,17 metabolites were significantly decreased,and 31 metabolites were significantly increased;There were 14metabolites significantly downregulated and 22 metabolites significantly upregulated in the100 m M and 200 m M salinity groups.During the entire operation period,the metabolism of the 100 m M group mainly involves the decomposition of proteases secreted by nutrients such as protein and glucose in the culture medium into various amino acids such as tyrosine,threonine,L-isoleucine,hisitidine,etc.These amino acids are further transformed with other amino acids,adenosine,purine,etc.,participating in the fermentation and conversion into Acetyl-Co A,which is then converted into acetate,which is then produced by the electrogenic bacterium G sulfurreducens utilization.（3）Preliminary study on the application of microbial fuel cell with interspecies consortium for treating actual kitchen waste water:Performance of biologically enhanced treatment of actual kitchen waste water from high to low was shown as S&TB107^T&PCA>S&TB107^T>S（sludge）.In the S&TB107^T&PCA reactor,the protein degradation rate in the second cycle was 57.80%,which was 2.49 times and 1.22 times higher than that of the S（sludge）group MFC and the S&TB107^Tgroup MFC,respectively.The COD removal rate in the second cycle of the S&TB107^T&PCA reactor（55.60%）was the best,which was 15.50%higher than that of the first cycle（48.14%）,and 1.59 times and 1.53 times higher than that of the S（sludge）group（35.00%）and the S&TB107^Tgroup（36.32%）,respectively.At the same time,the S&TB107^T&PCA reactor also obtained the highest potential（238.86 m V）in the second cycle,which was 27.07%higher than that of the first cycle potential.