Study On Two Phase Anaerobic Fermentation With Straw By Steam Explosion Pretreatment

In the fossil energy increasingly scarce, energy situation is becomingincreasingly tense today, the human search for alternative or supplementary energyand improve energy utilization efficiency is more and more urgent requirements.According to the situation of our country, the current total crop straw resources arerich in China but the utilization level is low, as can be used for biogas fermentation,can not only solve the problem of environmental pollution due to burning of straw,the abuse of chemical fertilizers caused, can also ease the tension of energy to thesocial pressure. At the same time, steam explosion pretreatment has been the majorityof scholars proved that straw is an effective pretreatment method. But the specialstudy the pretreatment for biogas production by anaerobic fermentation characteristicsis not much.This paper is in the Ministry of agriculture "the introduction of internationaladvanced agricultural science and technology" project: straw anaerobic fermentationtechnology introduction, digestion and innovation (No.2010-s252011-s15) forfinancial support。In this paper, the two-phase anaerobic fermentation test of corn straw steamexplosion pretreatment, compared with single-phase anaerobic fermentation test, firstselect the different concentration of material, analysis of variation characteristics ofpH, VFAs acid production phase and its influence on anaerobic fermentation,secondly, to study the fermentation conditions of two-phase anaerobic, most optimumprocess parameters obtained acid production phase and methanogenic phase, two-phase anaerobic fermentation. Finally the analysis process of two-phaseanaerobic reactor and single-phase anaerobic reactor operation, through the change ofpH value, VFAs content, change the gas and methane, the main conclusions can bedrawn as follows:(1) comparing the different effects of TS concentration on anaerobic digestionwas found, a higher concentration of TS, the pH value of the feed solution decreasedfaster, and long time maintained at lower pH value, resulting in liquid acid, is notconducive to the fermentation, the fermentation period prolonged, at the same time,high concentration the fermentation effect on gas production and methane content isoften large, gas production and methane content with the increase of TS and decrease.Therefore, test selection of reaction liquid TS concentration of4%for the subsequentexperiment.(2) in the analysis and comparison of three kinds of volatile fatty acid content inthe course of the experiment, found that microbes to acetic acid and butyric acid usingmore, throughout the fermentation cycle variation of the content of acetic acid andbutyric acid, but with less of propionic acid.(3) for the anaerobic fermentation of different temperature, considering the lowtemperature, the physiological activity of the microorganism was inhibited, theorganic acid utilization efficiency is not high, gas production and methane content islow, therefore,35℃two-phase anaerobic fermentation experiment temperatureselection test.(4) for two-phase anaerobic fermentation, two-phase anaerobic fermentationdevice designed by the authors, comparison of different flow methane results show, inthe back flow rate is120mL, can obtain higher biogas production and methanecontent, was11005mL and68.3%respectively.(5) in the analysis of two-phase anaerobic reactor and single-phase anaerobicreactor operation process, by changing the pH value, VFAs content, change the gasand methane, the two-phase anaerobic fermentation process through the acidogenicphase buffer, two-phase reactor methanogenic bacteria of pH value fit a wider range,more resistant to shock load and environmental change, the unit of organic matteraverage gas production reached2861.3mL/gVS, in the treatment of crop straw waste,two-phase anaerobic technology shows great advantage.