【作者】 李宁；

【导师】 王晓昌；

【作者基本信息】 西安建筑科技大学 ， 市政工程， 2009， 硕士

【摘要】 在世界能源短缺和石油危机的情况下,发展可再生能源,特别是生物质能源是解决能源问题的重要出路。燃料乙醇由于其丰富的原料来源成为世界各国的首选生物质能源。乙醇发酵以三大类物质为主:糖、淀粉和纤维素物质。前两种物质主要来源于粮食,威胁着人类的生存,不能大范围的推广,因此纤维素乙醇发酵是成为未来发展的必然趋势。由于纤维素结构的复杂,发酵前要对其进行预处理,将其降解为微生物可直接利用的单分子糖、有机物等。目前纤维素的水解方法以物化为主,成本高,操作不便,且易产生抑制产物影响其代谢功能。本研究的目的就在于用不同的方法培养真菌使其成为活性污泥中的优势菌群,为纤维素乙醇发酵提供新的糖化途径。实验采用SBR反应器,在人工配水基质中分别投加普通活性污泥、酵母粉和土壤上清液三种不同微生物来源接种培养真菌。本实验一个周期运行6h,进水5min,反应时间4.5h,静置沉淀lh,出水闲置0.5h。接种污泥取自西安市邓家村污水厂二沉池的污泥回流系统。观察实验过程中的污泥生物相和真菌菌落的平板计数,得到如下结论:(ⅰ)接种土壤上清液培养真菌是效果最好的一种方式;(ⅱ)与其它两种方式比较,接种土壤上清液后,真菌繁殖迅速,菌丝很长且相互交织缠绕在一起;(ⅲ)实验还检测了不同条件下的水质变化情况,结果表明:各种情况下对有机物的去除率都在70%以上,相对而言,活性污泥的处理效果较差一些;各种条件下对氮的去除都很低,不到30%,相比而言,投加土壤上清液后对氮的去除最好。通过比较三种方式在真菌数量、污泥形态以及对废水处理效果方面的变化,研究指出,土壤上清液在酸性条件下接种真菌是培养真菌效果较好的一种方式。更多还原

【Abstract】 Because of the shortage of resources and crisis of oil,bioethanol will be the first choice during the development of bioenergy in the world.So far,three kinds of substances are applied for the bioethanol fermentation,i.e.,saccharide,starch and cellulose.However,saccharide and starch are also important to human;the bioethanol fermentation using these two kinds of resource is thus disencouraged. Therefore,the most important approach for bioethanol fermentation is focused on the utilization of cellulose that is widely available in agrictural industries.Cellulose must be saccharified into micromolecule matters which can be used by microorganism directly before fermentation.However,the pretreatment of cellulose by means of chemical reaction is not ecologically flexible due to its high cost of reagents,complex operation as well as some harmful by-product for ethanol fermentation.Therefore,the scope of this study is set on the bio-pretreatment of cellulose especially on the process of saccharifing cellulose by means of fungus.Activated sludge,yeast and soil from grass round were utilized as seed fungus, respectively.A sequencing batch reactor(SBR) was employed in this study.It was operated in a sequence of 5min feeding,4.5 hours aeration keeping a very low concentration of dissolved oxygen,1 hour sedimentation and 0.5 hour withdrawing, resulting in a cycle length of 6 hours.By examing the sludge morphology and plate count of fungus colony,the following results could be obtained:(ⅰ) inoculation with soil was the best approach for fungus,followed by adding yeast and activated sludge;(ⅱ) fungus those inoculated from soil grew much quickly that the other two,and the mycelium were long and interwined;(ⅲ) concerning on water quality,70%of COD,TOC could be effectively removed in all the experiments and the system with activated sludge seed showed the lowest efficiency.No more than 30%ammonia could be removed in all the tests and the system with soil showed the highest removal efficiency.It can be concluded that the inoculation from soil maybe the best approach for the growth of fungus.更多还原