光发酵细菌生物膜法强化产氢调控

发布时间：2018-02-05 17:02

  本文关键词： 光发酵制氢 生物膜 胞外聚合物　出处：《哈尔滨工业大学》2016年硕士论文　论文类型：学位论文

【摘要】：针对光发酵细菌絮凝困难、细菌随出水严重流失和反应装置运行稳定性差等主要问题。本论文采用光发酵细菌性形成稳定的生物膜解决这一问题。首先研究载体的投入对光发酵细菌生物膜形成、细菌生长和产氢的影响,并对生物膜形成和产氢关键参数进行优化调控,然后多尺度考察了光发酵细菌生物膜促进产氢的机制。本论文的目的是通过形成生物膜使反应装置能够高效稳定产氢,为后续工业化生产提供技术支持和理论依据。载体加入对产氢培养基细菌生长没有明显影响。载体的投加使得反应体系产气过程高效产气时间从2-5d拓宽到了1-10d,累积产气量达到4300 m L/L,相比于对照组2120 m L/L提升约100%,氢气浓度由60%提高约到70%,产氢量由1060 mLH2/L提升到2580 m LH2/L,产氢量提高约180%,同时产气过程更加平稳持续。生物膜法反应装置底物最终可利用到74mg/L而对照组反应终止时底物仍剩余320mg/L,对应底物转化效率由24%提高到58%。针对反应装置关键参数进行优化调控时,通过综合考虑并比较产氢量、运行时间、产氢速率和底物利用率等几个方面,证明4 g/L碳源浓度、0.5 g/L L-半胱氨酸浓度、10cm*1的载体长度数量组合对对应是最优的反应装置条件。同时生物膜的出现使得反应装置能够抵抗外界环境波动并维持产氢能力。实验证实生物膜的形成可以促进光发酵细菌对底物更充分的利用,并更高效稳定的产生氢气,对于反应装置整体效能有着极强的提高作用。最后,多尺度对生物膜促进产氢机制进行分析。发现生物膜的形成使得光发酵细菌固氮酶和产氢酶这两种产氢关键酶活性均得到提高,直接增强了细菌产氢能力。针对光发酵细菌胞外聚合物进行研究表明,生物膜并没有改变细菌EPS元素的相对含量,而是使得细菌胞外聚合物(Extracellular Polymeric Substances,EPS)结构尤其是苯环结构和氢键发生改变,使得细菌表面能下降,有利于细菌与基质的物质和能量交换,同时细菌形成小凝聚体,导致细菌EPS结构松散、浓度下降,将更多的能源和物质转化为氢气。生物膜的形成能够宏观调控整体反应装置,并提供生物膜细菌和游离细菌两种生存策略,所以细菌可以有机分配能源和物质,同时满足自身生存和产氢的需求
[Abstract]:It is difficult to flocculate photofermenting bacteria. The main problems such as the serious loss of bacteria with the effluent and the poor stability of the reactor were solved in this paper. In this paper, the biofilm was solved by the formation of stable biofilm. Firstly, the input of the carrier to the biofilm of the photofermenting bacteria was studied. Form. The effects of bacteria growth and hydrogen production on biofilm formation and key parameters of hydrogen production were optimized. Then the mechanism of biofilm promoting hydrogen production by photofermenting bacteria was investigated in multi-scale. The aim of this thesis is to make the reactor to produce hydrogen efficiently and stably by forming biofilm. The addition of carrier has no obvious effect on the growth of bacteria in hydrogen production medium. The addition of carrier makes the efficient gas production time of reaction system widen from 2 to 5 days. 1-10 days. The cumulative gas production reached 4300mL / L, which was about 100mm higher than that of the control group (2120mL / L), and the hydrogen concentration increased from 60% to 70%. Hydrogen production increased from 1060 mLH2/L to 2580 mLH2/L, and hydrogen production increased by about 180%. At the same time, the gas production process was more stable and sustained. The substrate of the biofilm reactor could be used to 74 mg / L at the end of the reaction, but the substrate was still 320 mg / L when the reaction of the control group was terminated. The conversion efficiency of substrate was increased from 24% to 58. When the key parameters of the reactor were optimized, the hydrogen production and operation time were considered and compared. The hydrogen production rate and substrate utilization rate proved that the concentration of 4 g / L carbon source was 0.5 g / L L-cysteine concentration. At the same time, the biofilm can resist the fluctuation of the environment and maintain the hydrogen production ability. The shape of the biofilm has been confirmed by experiments. It can promote the utilization of the substrate by the bacteria of photofermentation. And more efficient and stable production of hydrogen, for the overall efficiency of the reactor has a strong improvement. Finally. The mechanism of biofilm promoting hydrogen production was analyzed in multi-scale. It was found that the formation of biofilm increased the activity of two key hydrogen-producing enzymes, nitrogenase and hydrogen-producing enzyme. Direct enhancement of bacteria hydrogen production capacity. The study of photofermentation bacteria extracellular polymer showed that the biofilm did not change the relative content of bacterial EPS elements. The structure of extracellular Polymeric substances-EPSs, especially the structure of benzene ring and hydrogen bond, were changed. The surface energy of bacteria is decreased, which is beneficial to the exchange of substance and energy between bacteria and matrix. Meanwhile, bacteria form condensates, which leads to the looseness of EPS structure and the decrease of concentration. The formation of biofilm can macro-control the overall reaction device and provide biofilm bacteria and free bacteria two survival strategies so bacteria can allocate energy and substances organically. At the same time to meet their own survival and hydrogen production needs
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TQ116.2
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本文编号：1492373