Study On The Characteristics Of Facultative Pretreatment And Anaerobic Fermentation Of Straw And Design Of Joint Device

Our country is rich in biomass and huge reserves.There are some problems,such as low utilization rate and environmental pollution.Anaerobic fermentation of straw is an important and effective way for the utilization of straw resource,but because of its molecular structure of straw itself in the presence of a large number of high bond energy of the hydrogen bond is difficult to crack in the decomposition process,resulting in the anaerobic digestion process is slow,low gas production.Therefore,in order to improve its gas production efficiency,it must be pretreated fully and effectively before anaerobic fermentation.Biological pretreatment can effectively destroy the stable crystal structure inside the straw and make the hydrogen bond in its structure break as much as possible,and break down into more small molecule organic matter that can be easily utilized.At the same time,in the process of preprocessing and decomposition,due to the existence of a large number of microbial metabolism,it is accompanied by the production of objective biothermal.At present,although there is a lot of research on the pretreatment technology of Compound microorganism at home and abroad,the utilization of related metabolic heat is rarely designed.At the same time,the anaerobic fermentation characteristics,the effect of gas production and the optimization of the reaction conditions were not carried out.The design and research of pretreatment and anaerobic co fermentation equipment for biothermal utilization of the pretreated raw material still need to be carried out.The related reaction characteristics and reaction effects have not yet been involved.Based on the above problems,the related problems were tested and explored by using the 30 L preprocessing and automatic fermentation equipment designed and completed by the laboratory.Single factor experiments were carried out in four aspects,including pretreatment,fermentation reaction temperature,the mixing rate and the ratio of carbon and nitrogen.The experiment period is 30 days.In the whole experimental period,daily production gas,total gas production,methane content and p H value of reaction fluid are recorded and analyzed.Experimental results show that the composite microbial pretreatment can effectively improve the gas production of anaerobic fermentation of corn stalk reaction in biogas and the cumulative gas production,the compound bacteria treated straw biogas production than the other two groups about 19% higher,not easy to produce acid accumulated gas production peak methane content remained above 50%;the mixing has obvious effect on the fermentation process,the Rev 45r/min accumulative gas production rate of the total gas production is at least 7.58% under the rest condition,in the speed of fermentation of corn straw anaerobic advantage under the experimental conditions was 45r/min.Corn straw for biogas production by anaerobic fermentation of the total comparison in the reaction temperature: 35? >40? >30? >45? >25?,and when the temperature is 35? when the gas production rate reached a maximum peak at an earlier time,the cumulative gas production was 15.5% higher than that in other conditions.;the methane content in the gas output 8.65% higher than other experimental temperatures.The effect of carbon and nitrogen ratio to 25:1 is obviously better than that of other groups,and the methane content is relatively high,and no acid inhibition occurs.For the experimental optimization of response surface method of anaerobic fermentation,single factor test results showed that the pretreatment method for the pretreatment of corn straw as composite bacteria,carbon and nitrogen ratio was 25:1,the stirring rate is 45r/min,the temperature is 35?,biogas production rate of gas production is the highest.By using Box-Behnken optimization test and mathematical model of response surface analysis,the optimum conditions of anaerobic fermentation conditions: determine the composite microbial pretreatment,temperature is 38.2?,C/N is 26.6:1,the stirring rate is 47.2r/min,the gas production rate is: 408.5m L·g-1TS,The effects of various factors on the rate of gas production were in turn: Temperature > C/N > Stirring rate.The calculated total input heat value is 4.74 MJ,the total output heat is 4.65 MJ,and the total heat balance of the reaction process is in the allowable range.Considering only a single experiment,the biological heat of the pretreatment process used at the end of each experiment can save at least 16.2MJ of heat energy for the anaerobic fermentation heating system.Based on relevant data of above experiments and research and rules in the realization of the system and material continuous heat production continuously and maximize the utilization of heat based preprocessing of microbial output on the design of the reaction system and anaerobic fermentation tank equipment and system model and tank structure and size data.This research provides an important reference for the construction of the related equipment and the research and design based on the existing research and design for the experimental research and verification of the equipment.