Study On The Mixture And Interaction Of Anaerobic Digestion Methanogens And Acetogenic Bacteria

Energy supply and environmental protection are two hot issues in the world.At the same time of social and economic development,a large number of pollutants have been produced in agriculture,industry,forestry and other fields.Under this background,the technology of anaerobic digestion and biogas production that can handle both organic pollutants and energy can be developed rapidly.It can make full use of various organic wastes,reduce waste emissions and pollution,and reduce greenhouse gases;the biogas produced can also be used for power generation,or purified and used as natural gas;the biogas slurry produced by fermentation is returned to the field,which is beneficial to Improve soil and produce green organic food.Although the biogas technology has reached the industrial level,such as slow start of anaerobic digestion system,insufficient utilization of raw materials,low methane production rate,ammonia suppression and acid suppression.Especially the problem of acid inhibition caused by the accumulation of volatile fatty acids(VFA)limits the fermentation efficiency of anaerobic digestion.In the face of this problem,researchers have focused on the core microorganisms of anaerobic digestion.In the two steps of anaerobic digestion,acid production and methanogenesis,a series of biological enhancement studies have been performed,such as shortening the start-up time of fermentation systems;A variety of fermentation raw materials;addition of specific microbial communities;reduction of the p H of the reaction system,etc.,but there is currently no publicly reported optimization plan for the microbial strain mix and the amount of substrate added.The purpose of this paper is to provide an optimized value for the compounding ratio and substrate addition amount of acetic acid-producing bacteria and methanogens in the process of anaerobic digestion,thereby effectively improving the VFA removal rate and conversion efficiency of anaerobic digestion,and optimizing The value can more accurately guide the anaerobic digestion process,which is suitable for application in small-scale fermentation tanks in the laboratory and can also be extended to large-scale industrial fermentation units.The experimental design is as follows:(1)Experiments to test the substrate inhibitory concentrations of acetogenic and methanogenic bacteria of different nutrient types.Design experimental design gradients based on suitable substrate concentrations and limit substrate concentrations commonly used in the literature,and perform experimental verification.Based on the removal rate,we can conclude that within a certain substrate concentration range,the substrate can be better consumed and transformed.Too high or too low substrate concentration is not suitable for the growth of anaerobic bacteria,so We took the best suitable substrate concentrations measured experimentally HPr 3000 mg / l,HBu 4000 mg / l,Et 4000 mg /l,HAc 5000 mg / l for subsequent domestication experiments.(2)Use the optimal substrate concentration obtained from the above experiments to domesticate the sludge.To enrich the bacteria with a single substrate,each generation is domesticated for ten days,and a total of four generations are domesticated.The substrate removal rate will reach 95%.Prove that domestication was successful.From the test data of VFA and COD during the experiment,it can be seen that the removal efficiency of HPr,HBu,Et,and HAc increases with each transfer and passage.After four transfer enrichment cultures,the VFA removal rate was greater than 95%,and a single substrate was obtained.The substrates were propionic acid,butyric acid,ethanol-producing bacteria,and methanogenic substrate with acetic acid.bacteria.(3)Finally,we use the Design Expert software to design a set of CCD experiments to investigate the compounding experiments of acetate-producing bacteria and methanogens of various substrates,which are sludge bacteria acclimated to substrates HPr,HBu,Et,and HAc,respectively.In the experiment,the M / A ratio was taken as the relative amount of its VSS concentration,the concentration of different substrates was selected as the main factor,the VFA removal rate was used as the reference index,and the Design Expert software was used to design the CCD experiment.The experimental results show that when M / A = 2.5,HPr = 1125.0mg / L,HBu = 1833.4mg / L,Et =2012.4mg / L,and HAc = 1727.5mg / L,the substrate removal rate is the highest,with an average of more than 70%.This test involves an experimental method to investigate the optimal ratio of the compounding ratio of acetic acid bacteria and methanogens and the amount of substrate added during anaerobic digestion.Initially,the optimal value of the single substrate was obtained through the exploration of the amount of substrate addition,and then the optimal value was used to enrich and domesticate the single substrate.After four generations of domestication,the single substrate was enriched and polluted.Mud.Finally,the CCD experimental design was used to carry out the experiment of the optimized value of the compounding ratio and the added amount,and the control group was used for comparison to obtain the true value of the optimized value of the compounding ratio and the added amount.This method opens up a new direction for the study of anaerobic digestion microorganisms.It is highly referential and has obvious effects.It can improve the removal and conversion of VFA in anaerobic digestion and improve the overall efficiency of anaerobic digestion.