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木质纤维素类、污水污泥、有机废水等废弃生物质中蕴含着巨大的能量，随着全球越来越严重的能源及环境问题，使用绿色、清洁可持续的生物技术转化废弃生物质替代传统的化学或物理方式生物质处理工艺变得越来越重要。氢气和电能作为传统生物质处理过程中的主要输出物，也可以被微生物处理生物质过程中产生，且反应条件温和无需高温高压的环境。本研究以氢气及生物电为目标产物，利用废弃生物质为底物，通过微生物转化的方法开展研究，主要研究内容为：1) 以厌氧常温菌株C.cellulolyticum DSM 5812为出发菌株，调控其厌氧发酵过程中关键发酵条件pH，以玉米秸秆为底物，厌氧发酵获得大量氢气及有机酸产物，当底物分别为10g/L、20g/L、30g/L玉米秸秆时，最终产氢量为571ml/L、901ml/L、1163ml/L，C.cellulolyticum降解玉米秸秆主要有机产物为乙酸、乳酸和少量的乙醇，前期主要有机产物为乙酸，当乙酸产量达到1.6g/L后随着反应的进行，会引起乳酸的大量积累，乳酸积累到1.6g/L左右，乙醇积累速度也会增加，但最终产量低于0.4g/L；2) 以产电菌Shewanella.putrefaciens为出发菌株，将S.putrefaciens和玉米秸秆发酵液的耦合，构建微生物燃料电池与微生物电解池。S. putrefaciens可只利用发酵液生长，GC/MS分析，发现S. putrefaciens可对多种芳香化合物进行降解，其中2，3二羟甲基呋喃、4-羟基-3-甲基 苯乙酮、2，6-二甲氧基苯酚、2,4-双（1,1-二甲乙基、4-甲基-2,5-二甲氧基苯甲醛降解率分别为100%、74.9%、65.8%、85%、70.5%；S. putrefaciens利用玉米秸秆发酵液为底物构建微生物燃料电池，当底物分别为10g/L、20g/L、30g/L灭活C.cellulolyticum玉米秸秆发酵液时，最大功率密度分别为16.9 mW/m2、15.7 mW/m2、15.1 mW/m2；在微生物燃料电池构建的基础上构建微生物电解池，在外接0.7V电压Pt催化下情况下，每克VFAs可产H2 11.5-12.9ml。3) 以厌氧活性污泥为接种液构建了性能良好的MFC，输出功率可达到1247 mW/m2,内阻为143Ω，库伦效率为9.9%，COD去除率达到64%，厌氧活性污泥有大量CH4及极少量H2产生，未有电子输出；MFC未有CH4和H2产生，有电子输出。实现厌氧活性污泥接种MFC能量输出以电能为唯一形式，从而避免沼气发酵过程中沼气需要分离、储存、运输、能量难以利用的问题。高通量测序对MFC运行前后细菌及古菌菌群变化分析，古菌菌群变化不大，细菌菌群变化非常明显，与原始厌氧污泥相比MFC菌群多样性指数有所降低，但优势菌群更加明显， MFC 产电能力直接相关的克雷伯氏菌属（Klebsiella）富集并成为优势菌属，相对丰度达到16.73%，此外氢噬胞菌属（Hydrogenophaga）也大量富集可能是产电相关菌属。综上所述，本研究提出一种废弃生物质微生物利用的新工艺。也为微生物转化生物质产电产氢的相关研究提供了技术方法和理论支持。; It was contain huge amounts energy in waste biomass, such as lignocellulose, sewage sludge and organic waste wate. In view of the increasing serious global energy and environmental problems. Green, clean and sustainable biotechnology as an alternative to traditional biomass treatment process use to convert waste biomass into target products. Hydrogen and electric as the main output of the traditional biomass treatment process, can also be produced by microorganisms in the process of biomass treatment. And the reaction conditions are mild without high temperature and high pressure. In this study, hydrogen and bioelectricity were used as target products, and waste biomass was used as substrate. 1) Taking C.cellulolyticum DSM 5812 degradated corn stover, with anaerobic mild culture and fermentation conditions regulation especially pH during the fermentation process. A large amount of hydrogen and organic acid products were obtained. When the substrate was 10g/L, 20g/L and 30g/L corn stover the final H2 yield was 571ml/L, 901ml/L and 1163ml/L respectively. The main organic products of corn stover fermentation were acetate, lactate and a small amount of ethanol. Acetate was the main organic product in the early stage of fermentation. Lactate will be accumulated after the concentration of acetate reached 1.6g/L. And the accumulation of ethanol increased after the lactate accumulated to about 1.6g/L, but Lower than 0.4g/L.2) Shewanella putrefaciens as was used to construct the microbial fuel cell and the microorganism electrolysis cell，and corn stover fermentation liquid to fed it. S. putrefaciens can use fermentation broth growth without other nutritions. It was found that S. putrefaciens can degrade a variety of aromatic compounds through GC/MS analysis, which 2,3-dihydrobenzofuran, 4-Hydroxy-3-methylacetophenone, 2, 6- two methoxy phenol, 2,4-bis(1,1-dimethylethyl)-phenol, 4- methyl -2,5- two methoxy benzaldehyde degradation rate were 100%, 74.9%, 65.8%, 85%, 70.5% respectively. The maximum power density were 16.9 mW/m2, 15.7 mW/m2, 15.1 mW/m2 respectively when the concentration of corn stover were 10g/L, 20g/L and 30g/L. On the basis of MFC, a microbial electrolysis cell was built. Per gram VFAs could used to produce for about 11.5-12.9ml of hydrogen under the condition of addation 0.7V external voltage and catalysis by Pt.3) A good performance microbial fuel cell(MFC) was constructed with anaerobic sludge as seed solution. The voltage reached 0.62 V with the external resistance of 1000 Ω. The power density reached 1247 mW/m2, the internal resistance was about 143 Ω. 63.6% of the COD was removed in MFC. There have no CH4, H2 and electronic production compare with anaerobic sludge had CH4 and H2 produce without electronic output. Electronic produced of MFC was to avoid the problem of separation, storage, transportation and energy utilization in the process of biogas fermentation. The changes of bacteria and archaea of MFC were analyzed by high throughput sequencing. There was no obvious change of archaea, and tremendous different of bacteria. Compared with the original anaerobic sludge, the OTU diversity index of MFC decreased, but the mainly bacteria group was more obvious. The concentration of Klebsiella who directly related to the electricity production of MFC increased to 16.73%, and Hydrogenophaga was also enriched in this process.To sum up,this study proposes a new technology for microbial utilization of waste biomass. It also provides technical methods and theoretical support for the related research of microbial conversion of biomass to electricity and hydrogen production.
|丁建军. 微生物厌氧转化生物质产氢产电研究[D]. 中国科学院研究生院,2018.|
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