【作者】 王哲；

【导师】 马放； 魏利；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2011， 硕士

【摘要】 随着生物絮凝剂工业生产和应用的需求不断扩大,价格昂贵的培养基成为了制约其发展的关键因素,寻求廉价底物替代培养基具有十分重要的作用。本课题以牛粪沼液作为接种物,分别在好氧液态发酵反应器和厌氧干发酵反应器中对水稻秸秆进行发酵,将水稻秸秆不同工艺下的发酵液作为底物替代传统产絮菌培养基,通过对反应器运行过程中各参数的变化以及发酵液的产絮效果研究,寻求出一种贴近于自然的秸秆降解方法,及更易于工业大规模推广的复合型生物絮凝剂的制取方法。以牛粪及沼液的混合物作为接种物,水稻秸秆为底物的好氧预处理过程进行了探讨,分析了好氧预处理过程中的微生物群落变化,认为好氧预处理过程后期富集驯化出一定数量的纤维素降解菌菌群,另外,推测系统中有新种出现。将富集驯化后的菌液投入到好氧液态发酵反应器,添加新鲜秸秆,反应器运行到120d时pH达到9.2左右。TOC在初期发酵阶段逐渐升高,两次添加接种物后均降低,随后逐渐升高,TN变化趋势同TOC,C/N维持在20:1左右。反应器运行稳定,实现了对水稻秸秆的有效降解。以牛粪及沼液的混合物作为接种物,水稻秸秆为底物的厌氧干发酵过程进行了探讨,采用内循环喷淋的方式运行厌氧干发酵反应器,反应器运行稳定。发酵初期,pH值迅速下降,30d后pH值缓慢上升,反应器中部和下部pH值始终保持同趋势变化。厌氧干发酵过程没有出现丙酸积累现象,发酵类型为丁酸型发酵。厌氧发酵液中总有机碳(TOC)含量随时间增加,总氮(TN)含量随时间减少,120d后C/N比达到15:1。通过分析认为水稻秸秆中半纤维素和纤维素得到有效降解,木质素轻微降解,同时水稻秸秆结构中的分子内氢键被破坏,水稻结构发生明显改变。推测厌氧干发酵过程中的优势菌群为厚壁菌门、变形菌门、拟杆菌门微生物。对不同工艺条件下的发酵液与传统产絮培养基配比形成的复合型产絮培养基产絮能力进行了探讨,好氧糖化液与传统产絮培养基最优配比为1:3,第67d和第109d的糖化发酵液与传统产絮培养基复合形成的复合型产絮培养基絮凝率较高;厌氧发酵液与传统产絮培养基最优配比为1:1,第100d的厌氧发酵液与传统产絮培养基复合形成的替代产絮培养基絮凝率最高,为92.45%,絮凝效果优于传统产絮培养基。厌氧干发酵反应器的发酵液与传统产絮培养基配比形成的复合型产絮培养基絮凝实验取得良好的絮凝效果原因可能有两点:一是厌氧发酵液复杂的成分为产絮菌提供了更丰富的底物;二是厌氧发酵液中存在的未被降解的木质素等组分在絮凝过程中对絮凝体的形成起到了促进作用。更多还原

【Abstract】 With the increasing demand of biological flocculant industry production and application, the expensive culture medium becomes the key factor that limits the development of biological flocculant, it’s necessary to seek the cheap alternative medium. In this topic, the performance of aerobic saccharification reactor and the anaerobic fermentation reactor which takes cow dung biogas slurry as inoculum and taken rice straw as substrate were discussed. According to the varieties of parameters during the reactor operating and the flocculation effect of fermentation liquid, a kind of straw decomposition method that closing to the natural can be found, and ti is easier to promote the complex industrial scale bio-flocculant Preparation.The mixture of cow dung and biogas slurry was taken as inoculum for aerobic pretreatment, according to the analysis of microorganism communities, it can be found that the advantage bacterium in the system are cellulose degradation bacterium and Clostridia sp.. In addition, it is speculated that a new species appeared in that system. The fresh rice straw and the broth that including enriched and domesticated cellulose degradation were added in the aerobic saccharification reactor. In the early stage, TOC increased gradually, after adding the biogas slurry TOC decreased sharply, TN also increased with fermatation time. pH reached 9.2 finally, C/N remained at around 20:1, the reactor operated stably, and degraded rice straw effectively.The mixture of cow dung and biogas slurry was taken as inoculum and the rice straw was taken as substrate for the anaerobic fermentation reactor, the reactor operated stably by the mode of inner loop. The pH decreased rapidly at the initial fermatation, then rised slowly after 30d. Dry anaerobic fermentation reactor did not appear the phenomenon of acid accumulation, and the fermentation type is butyric acid type fermentation. TOC increased with time while TN decreased with time, C/N reached 15:1 finally. The hemicellulose and cellulose degradated effectively, lignin degraded slightly, and the intramolecular hydrogen bond destroyed, the structure changed significantly. It is speculated that the advantage bacterium are Firmicutes, Proteobacteria, Bacteroidetes.Then, we took the different fermentation liquids and the traditional flocculation culture medium mixture under different ratio as compound flocculation culture medium. The optimal ratio of aerobic saccharification liquid with traditional flocculation culture medium is 1:3, the aerobic saccharification liquid of the 67d and the 109d compound with the traditional flocculation culture medium under optimal ratio reached the highest flocculation efficiency. While the optimal ratio of anaerobic fermentation liquid with traditional flocculation culture medium is 1:1, the anaerobic fermentation liquid of the 100d compound with the traditional flocculation culture medium under optimal ratio reached the highest flocculation efficiency, the flocculation efficiency is 92.45%, which higher than the traditional flocculation culture medium. The compound flocculation culture medium mixed with dry fermented liquid with tradiondal flocculation culture medium achieved excellent flocculation efficiency, the result attributed to two accounts: the complex components of anaerobic fermentation liquid offers the richer substrate species for the floc bacteria; the straw fractions have not been degraded exsited in the anaerobic fermentation liquid promote the process of the formation of flocs.更多还原