Research On The Methanogenesis Stage Of Anaerobic Digestion Enhanced By Composite Filler

With the rapid development of the world economy,the supply of fossil fuels is becoming increasingly fatigued,and non-renewable resources such as oil and coal are used unchecked.This not only depletes fossil fuels,but also causes damage to the global ecological environment.Biomass energy has gradually become a hot spot of research due to its advantages of easy availability of raw materials and green cleanliness.Anaerobic digestion is one of the most extensive and effective means of converting biomass energy into clean biogas.The anaerobic digestion process degrades organic matter through the interaction of microorganisms to produce biogas,which can be purified to produce biogas.However,the problems of slow anaerobic digestion methane production rate,long methane production lag period,low substrate degradation rate,and insufficient stability of the reaction system still need to be resolved.In recent years,studies have shown that carbon-based materials can promote anaerobic digestion to a certain extent and improve the methanogenic performance of the reaction system,but carbon-based materials still have problems such as loose structure and low biological affinity.Area enrichment and reunion have limited enhancement effect on anaerobic digestion.On the other hand,in the industrial application of anaerobic digestion,the addition of carrier fillers with high biological affinity can effectively fix anaerobic microorganisms and form anaerobic microorganism membranes,thereby improving the abundance and diversity of microorganisms in the system.Promote anaerobic digestion process.In this paper,based on the research status of anaerobic digestion of methanogenesis,we designed experiments to explore the effect of biofilm carrier(polyurethane)and carbon-based materials(conductive carbon felt)closely stacked composite filler on anaerobic digestion.According to the characteristics of the raw materials and carrier fillers used in each experiment,the effects and mechanism of organic material degradation and gas production promotion were analyzed.The main conclusions are as follows:(1)Using a mixture of glucose and small molecules of volatile fatty acids such as B,C,D,and valeric acid as a substrate,using polyurethane,conductive carbon felt and composite filler as a carrier,using 5 biofilms with a working volume of 5L Experimental research.The results show that after 55 days of domestication and acid culture experiments,the reactor filled with composite filler and polyurethane filler(R1,R2,R3)showed good system stability,and the acid removal rate of the composite filler reactor(R1)The removal rate of COD and COD can reach 90% and 60% respectively,which are 40% and 33% higher than the control reactor(R5),and the methane yield is increased by about 70%,which is significantly better than polyurethane and carbon felt fillers.The strengthening effect is obvious.Through microbial community analysis,composite fillers(R1,R2)can effectively enrich Clostridiaceae,Methanosaetaceae,Methanobacteriaceae,and Methanosarcinaceae,which can form effective on the surface Anaerobic microbial membrane.(2)In the semi-continuous anaerobic digestion experiment,the composite filler reactor has excellent performance in terms of system stability,organic load removal rate and methanogenic capacity,with COD removal rate and acid removal rate up to 95%.Compared with the control group,the methane yield increased by 25% and the methane content increased by 22%.In the experiment,the feeding and discharging operations caused the rapid loss of microorganisms in the reactor liquid phase,so that the acidification of the control group(R5)failed in the middle of the experiment.The composite filler plays a key role in the immobilization of microorganisms.The microbial film formed in the reactor is closely attached to the surface and internal pores of the filler to ensure the abundance and diversity of anaerobic microorganisms in the system.The digestion methanogenesis stage has a good strengthening effect.(3)In order to explore the effect of composite filler on the anaerobic digestion methanogenic capacity,this paper uses a methanogenic automatic monitoring device(BMP)for experiments.The results show that the electrical conductivity of the composite filler is much higher than the Pili(pilus)of anaerobic microorganisms(2.5～10 S/cm >> 0～18μS/cm),which makes the composite filler to Syntrophomonadaceae,Methanosarcinaceae and other electroactive microorganisms have a better enrichment effect,promote the DIET mechanism of methanogenic microorganisms,effectively shorten the lag period of methane production,and also increase the methane yield,the cumulative methane output is up to 392.4 m L/g VS,which can reach 79.02% of the theoretical value.Therefore,compared with a single filler,the composite filler has obvious advantages in microbial enrichment and electrical conductivity.It has excellent performance in the stability of the anaerobic digestion system,organic load removal,and methanogenic capacity.It can effectively strengthen the anaerobic digestion of methanogenic stage.