Effect Of Steam Explosion Pretreatment On Microstructure And Anaerobic Fermentation Characteristics Of Corn Straw

With the increasing lack of fossil fuels, and the increasingly urgency tense of energy situation, it is becoming even more urgent to search for alternative or supplementary energy and improve energy efficiency. Biomass energy has become one of the most important energy in the world for its safety and renewable. The total resource of crop straw in China is rich but the usage of it stays in a low level. If it can be used for methane fermentation, the environment problem and the energy crisis may be eased to a certain extent in our country.The main components of crop straw are cellulose, hemicellulose and lignin, and they forming a complex coiled structure, and by which the decomposing of cellulose and hemicellulose in fermentation process are forbade. Therefore, to make full use of straw resources, the straw physical structure must be destructed by pretreatment.The main methods of straw pretreatment are physical, chemical and biological methods. Each of these three pretreatment methods have its advantages and disadvantages, and there has not been a method content all the advantages, or has low cost but high efficiency and can promote in production.The Steam explosion pretreatment has been proved to be an effective method of straw pretreatment by majority of scholars. The corn straw is pretreated by steam explosion and the microstructure of it and an anaerobic fermentation is taken to investigate the effect of steam explosion pretreatment on the microstructure of straw and the anaerobic fermentation characteristics of straw.This Paper comprehensively reflected the study of the author, details are as follows:(1) Analysis the basic parameters of straw. The macro and micro structure and composition was analysed before and after steam explosion pretreatment to investigate the mechanism of steam explosion pretreatment to straw. It was shown that the microstructure and the contents of cellulose, hemicellulose and lignose changed after the explosion pretreatment.(2) Anaerobic fermentation of corn straw with and without steam explosion pretreatment to investigate the effect of steam explosion pretreatment on anaerobic fermentation characteristics of corn straw. It was shown that the biogas production rate of kilograms of VS. The maximum biogas production rate of dried corn straw was325.54mL/g under the condition of pressure is2.5Mpa, retention time is90s, and the TS of fermentation is4%; and that of the green straw is334.77mL/g with the TS of fermentation is3%. But the difference of the results under the pressure of2.5Mpa and1.5Mpa can be ignored, so1.5Mpa is the optimum pressure.(3) From the anaerobic fermentation experiments, it was shown that the fermentation circle of dried straw is longer than that of the green one under the high pressure2.5Mpa, but shorter than that one under1.5Mpa, and the biogas production rate of dried straw is lower than that of the green one.(4) From the energy analysis of the whole process, it was shown that Energy conversion efficiency of pretreated process is higher than unpretreated one by15.66%. But the Energy utilization efficiency is lower because of the high energy consumption of steam explosion pretreatment method.