Enhanced methane production from anaerobic digestion of cattle manure by adding iron oxide nanoparticles
To investigate the influence of metal additives on the anaerobic digestion of cattle manure and enhance fermentation efficiency,this study chose iron oxide nanoparticles(INP)as a representative metal additive.We compared the changes in daily methane production,total volatile acids,cellulose,and hemicellulose between reactors with INP added and control reactors that never received INP.Additionally,the impact of INP addition on microbial communities and key enzyme activities was further explored through microbial analysis.The results demonstrated that INP addition promoted cellulose hydrolysis and facilitated the degradation of volatile fatty acids,thereby enhancing methane production.When 625 mg∙L-1 of INP was added daily to the continuous reactor,the daily methane production reached 173.4 mL∙g-1∙d-1,38.3%higher than the control group.Even when the addition of INP ceased,methane production remained significantly higher compared with the control group(P<0.05).16S rRNA analysis revealed the enrichment of a pair of syntrophic microbial guilds Mesotoga,which oxidizes acetic acid,and Methanoculleus,a hydrogenotrophic methanogen.Metagenomic analysis revealed that the addition of INP significantly enhanced the activities of enzymes associated with both acetoclastic and hydrogenotrophic methanogenesis,particularly increasing the activity of the key enzyme in methane synthesis,methyl-coenzyme M reductase(EC 2.8.4.1)(P<0.05).This was identified as the primary reason for the increased methane production efficiency.Thus,the application of metal additives represented by INP is beneficial for methane production in anaerobic fermentation of cattle manure,thereby improving the efficiency of livestock manure energy utilization.
万方数据
维普
