【作者】 田永兰；

【导师】 张化永；

【作者基本信息】 华北电力大学 ， 环境工程， 2012， 硕士

【摘要】 本研究采用硫酸、乙酸和磷酸对青贮玉米秸秆进行预处理,与牛粪混合在高温条件下进行厌氧发酵产沼实验。通过对酸预处理秸秆的组成成分、酸预处理后混合原料厌氧发酵的产气特性与产物特性的研究,探讨了酸预处理对玉米秸秆和牛粪混合厌氧发酵的影响,以及提高玉米秸秆产沼效率和能力等问题。结果表明：(1)酸预处理增加了单位干重玉米秸秆中挥发性固体(VS)、脂肪、纤维素、半纤维素和木素所占比例,降低了玉米秸秆中蛋白质、淀粉和可溶性糖的比例,其中,乙酸预处理对蛋白质的影响最小,硫酸预处理对淀粉和半纤维素的影响最大,对脂肪和木素的影响最小,乙酸预处理对初始pH的影响小于硫酸和磷酸预处理；(2)三种酸预处理条件下,具有最佳产气效果的酸处理浓度分别为0%硫酸(即未经硫酸处理的对照组)、4%乙酸和6%磷酸,其累积产气量分别为50.72mL/g TS、71.70mL/g TS和75.26mL/g TS,0%硫酸、4%乙酸和4%磷酸试验组分别在反应第9、16和7天达到最高甲烷含量54.9%、63.6%和63.2%；(3)发酵过程中二氧化碳含量变化与甲烷趋势相似,但比甲烷含量提前降低,氢气含量的变化与之相反,硫酸和乙酸预处理延迟了产甲烷高峰的到来,而磷酸使之提前,并且乙酸和磷酸处理组中甲烷含量高于对照组；(4)发酵体系呈弱酸性,伴随发酵过程,总固体(TS)和VS含量降低,但降低程度因酸处理中酸的种类和浓度而异；(5)发酵过程中脂肪、纤维素、半纤维素和木素含量降低较大,但蛋白质、淀粉和可溶性糖含量降低较小,酸预处理增加了脂肪的降解量,乙酸和磷酸预处理对半纤维素降解作用明显,硫酸预处理有利于木素的降解,低浓度硫酸、高浓度的乙酸和磷酸预处理有利于淀粉和纤维素的降解。酸预处理玉米秸秆与牛粪混合厌氧发酵是提高生物能源产气效率的重要问题。本文在分子水平上对酸处理农作物秸秆制沼开展了实验研究,对酸处理的发酵过程影响进行了探索,研究结果对于农村生物质能源开发工程实践具有指导意义。更多还原

【Abstract】 In this study, the straw of silage maize was pretreated by3kinds of acids, known as sulfuric acid, acetic acid and phosphoric acid. After pretreatments, the straw was mixed with the cow dung and proceeded to the anaerobic fermentation under high temperature conditions. This experiment investigated the responses of maize straw to acid pretreatment, studied the biogas yield and character of anaerobic fermentation and analyzed the degradation of the substrate to obtain the impact of acid pretreatment on the anaerobic fermentation with mixed maize straw and cow dung.The results showed that:(1) The percent of VS, lipid, cellulose, hemicellulose and ligin content in the straw were increased by acid pretreatment, while the percent of protein, starch and soluble sugar were decreased. Acetic acid had less influence on protein content comparing with sulfuric acid and phoshoric acid. Sulfuric acid decreased the content of starch and hemicellulose more than other two acids, but increased the content of lipid and ligin. The effect of acetic acid pretreatment on the initial pH was more gently than the other two acids.(2) The highest accumulative biogas yield was50.72mL/g TS,71.70mL/g TS and75.26mL/g TS for sulfuric acid, acetic acid and phosphoric acid, when the acid concentrations were0%,4%and6%, respectively. For sulfuric acid (0%), acetic acid (4%) and phosphoric acid (4%) pretreament, the highest methane content was obtianed of54.9%,63.6%and63.2%respectively when the anaerobic digestion was proceeded for9,16and7days.(3) During the fermentation, the content of carbon dioxides which was advance decreased before the methane, and changed in the same way with the content of methane, while the content of hydrogen content was contrary changed. The peak yields of methane were delayed by sulfuric acid and acetic acid pretreatments and were brought forward by phosphoric acid pretreatments. The content of methane under acetic acid and phosphoric acid pretreatments were higher than that in the control test.(4) The fermentation system was faintly acid. Along with the fermentation, the total solid (TS) and VS of the system were variously dicreased according to different acid varieties and concentrations.(5) Lipid, cellulose, hemicellulose and ligin were the main compositions that were digested during the fermentation, while the protein, starch and soluble sugar were not. Acid pretreatment increased the utilization of lipid. Acetic acid and phosphoric acid pretreatments were helpful for the degradation of hemicellulose, while sulfuric acid pretreatments were helpful for the degradation of ligin. Low concentrations of sulfuric acid and high concentrations of phosphoric acid were helpful for the utilization of strach and cellulose.The anaerobic fermentation with mixed acid pretreated maize straw and cow dung is an important question in improving the efficency of bioenergy production. This study is conducted at molecular level to investigate the biogas production with acid pretreated straw, and explored the fermentation process influenced by acid pretreatments. The results are instructive for the engineering practice of bioenergy exploition in the village.更多还原