Study On The Characteristics Of Corn Stalk Dry Anaerobic Fermentation Based On Bio-pretreatment And The Utilization Of Residue Media

It's universally acknowleged that straw energy-oriented use can be achieved through the transformation of biomass energy crops such as straw into high value-added methane and organic fertilizer,especially in China with her abundant crops straw resources.Currently the dry anaerobic fermentation technology has become a research focus because it can improve the production volume.Howerever,because of the characteristic of high cellulose and the weak ability to digestion for anaerobic microbial,the application and production of straw biogas has been seriously limited.Therefore it's extremely significant to have a further reseach on pretreatment technology, efficient biogas production of dry fermentation and the depth utilization of the residue.My thesis revolve around corn stalk and bio-pretreatment to expound on the features and the factors of dry anaerobic fermentation.Based on the previous experiment,the conclusion has been reached that the process of mixed bacteria bio-pretreatment corn stalk and dry anaerobic fermentation biogas production.Through the analysis of the composition of fermentation residue, investigating feasibility of using residue as the matrix to cultivat strawberry. The main research contents are as follows:(1) Dilution-plate method is used on the guaiacol solid selective medium,aniline blue screening medium and a-naphthol screening medium,made use of the method that combine the qualitative screening with quantitative calcium lignin sulfonate degradation experiment to separate the lignin-degrading bacteria S4 which laccase activity is higher from rotten wood in the forest, the biological characteristics of this strains and the conditions of liquid fermentation produce lignin degradation enzyme were studied. Through the conditions for enzyme production of carbon source,nitrogen source,mentalion,surfactant,temperature,PH,inoculation amount and incubation time to research, the results show that the best carbon and nitrogen source of strains S4 is glucose and ammonium tartrate, temperature is 28℃,PH is 5.0,inoculation amount is 5% that is the best culture conditions, orthogonal design ascertain three main factors for influence Lac production is ammonium tartrate,Tween80 and glucose, the optimal combination of culture medium is that the glucose is 15g/L, ammonium tartrate is 0.2g/L, MnSO40.01g/L,Tween is 801/L; the main factors to affect Lip production is glucose and ammonium tartrate, the optimal combination of culture medium is that the glucose is 15g/L, ammonium tartrate is 0.4g/L, Tween is 800.5/L,MnSO40.015g/L.(2) Comprehensive the ability of produce enzyme and the results of compatibility experiment,using the principle of enzyme production complementary to make Phanerochaete chrysosporium,Trametes versicolor and strains S4 which could cooperate with degrade lignin screening from environment to mixed cultivation degradation corn stalks, through the degradation conditions of temperature,moisture,inoculation amount and incubation time to studied, the results showed that the culture conditions of mixed bacteria degradation corn stalks is 28℃,water content is 65%,inoculation amount is 5%,this moment, the degradation rate of lignin is faster after 7-15d disposed, the lignin degradation rate of solid state fermentation is 35.75% after disposed 20 days.The mixed bacteria will be used for the Bio-pretreatment before corn stalks dry anaerobic fermentation, combined the situation with the degradation of lignin,start-up dry anaerobic fermentation and produced biogas accumulated in 30d, determined that the time of mixed bacteria Bio-pretreatment corn stalks is 11d, after pretreatment the degradation rate of lignin is 28.74%,the degradation rate of cellulose is 17.74%,the degradation rate of hemicellulose is 28.35%. Using scanning electron microscope and infrared spectrometric analyzer to comparative analysis corn stalks degradation from beginning to end.From scanning electron microscopy we found that the surface morphology structure of corn stalks have change obviously, the aromatic rings and the ether bonds in the FTIR absorbed reduce, which speak volumes for that the mixed bacteria has strong degradation function to lignin.(3) On the basis of comparing gas production effect of different Bio-pretreatment, researched that the corn stalks after Bio-pretreatment with the mixed bacteria, in the different condition of temperature, particle diameter, solid concentration, the inoculum additives, C/N, the changes of stability of dry anaerobic fermentation production biogas and biogas yield, and adapt the Response Surface Methods to make sure that the best condition of dry anaerobic fermentation is the mixed bacteria Bio-pretreatment, temperature (35℃), particle size 1～3 mm, density of TS is 21.4%, the inoculum additives is 25.5%, the initial C/N is 30.2:1.In the optimal technological conditions, make the corn stalks dry fermentation experiment in a 1L reactor in a 100d fermentation period, the cumulative gas production is 31.78L,TS which is the fermentation materials that the gas yield is 0.476 L/g and the volume fraction of methane in biogas is 50.13% on average. It explain that after optimized the process conditions can effectively promote produce methane in the way of stalks dry anaerobic fermentation, and provide the theory basis for the reasonable design and operation of the corn stalks dry anaerobic fermentation system.(4) Though the experiment analysis of nutrient content and pollution index of the residue of corn stalks dry anaerobic fermentation. The results shows that the fermentation residue which the raw material is stalks rich of nutritional substances, among it all kinds of the nutrient content of residue is higher than biogas slurry, in residue the content of total-N,total-P and total-K are all higher, relative to the residue of the poultry feces after fermented in a higher level. Compare contamination control standards in agricultural sludge(GB4284-84),each heavy metal element content of residue in this laboratory condition are all in the standard range. It indicate that residue not only rich of nutrient element, and also can be used long-term used as a kind of raw material of efficient pollution-free organic matrix.(5) The study of making use of anaerobically digested slurry. The different ratio of the anaerobically digested slurry, the index like volume density,moisture content,pH value,EC value are all in a suitable scope, among it will promote the root development when residue:vermiculite is 1:2-3 and dry matter accumulated more, photosystem (PSⅡ) have larger photosynthetic electron acceptor library(Sm)which could accept more electronic, contributed to transfer in electron-transport chain and made the maximum conversion efficiency of light energy (Fv/Fm) and potential activity of PSⅡ(Fv/Fo) improve. The microflora composition of substance is changed after added proportional biogas residue and the presence of actinomycetes and bacterium in the strawberry rhizosphere matrix is improved obviously, in it if residue:vermiculite is 1:2 that bacteria/fungi is 3.09 times of control subjects and the proportion of actinomyces/fungi is as high as 76.23 times, the strawberry rhizosphere environment is improved when active agent of substance improve, it expressed that strawberry root vigor is improved 19.17% compared by control subjects and total root respiratory rate is improved significantly 47.67% compared by control subjects, the root system biochemical breathing metabolic pathway is converted into TCA breath pathway which is full of higher output and improve energy to plants for fine growth.(6) Under drought adverse environmental stresses, when residue:vermiculite=1:2 strawberry plants net photosynthetic rate of substance is improved significantly 44.39% compared by control subjects, increase the efficiency of water of plants usage, strawberry leaves PSⅡtransfer electrons are suffering considerable damage; under low temperature conditions when residue:vermiculite is 1:3 and made the Pn of leaves in high level,but the receptor side electronic of PSⅡtransfers from QA- to QB- has been a degree of restraint; under the condition of strong light when residue:vermiculite is 1:2 PIABS is higher than other processes obviously, the efficiency is high of photosynthetic electronic transfer. The research shows that when residue:vermiculite is 1:2 the stress resistance is strong of strawberry plants and it is an ideal culture substrate.