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Screening And Separation Of Anaerobic Bacteria To Produce Hydrogen And Its Evalution On Hydrogen Producing Efficiency

Posted on:2012-03-15Degree:MasterType:Thesis
Country:ChinaCandidate:X LiuFull Text:PDF
GTID:2180330335473858Subject:Biochemistry and Molecular Biology
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The samples were prepared from the bovine rumen, the omasum, the abomasum, the sewage treatment biological pool entrance and the biological sampling pool in plants. Then, the anaerobic bacteria were screened and isolated. The bacteria were identified and isolated by the indole test, the oxidase test, the spot test and thel6SrDNA sequencing technology. The growth curves of the bacteria were determined by culturing in the shaking flasks. The bacteria were developed in the anaerobic fluidized bed bioreactor. Finally, make the isolated and identified bacteria develope into the fermentation reactor to make the hydrogen producing efficiency evaluation. The results were as follows: 1. Three anaerobic bacteria were isolated from the bovine rumen, the omasum and the abomasum. Physiological and biochemical identification showed that the three anaerobic bacteria were positive during the indole test, but they were negative during the oxidase test and the spot test. The 16SrDNA sequence analysis showed that the similarity of their 16srDNA sequences was above 99%, which showed that the three types of facultative anaerobic bacteria were the same kind-Klebsiella pneumoniae.2. Two anaerobic bacteria were isolated from the the import of biological sewage treatment plant sludge and the bio-pool. Physiological and biochemical identification showed that the two types of anaerobic bacteria were positive during the indole test and the spot test, but they were negative during the oxidase test. The 16SrDNA Sequence analysis showed that the similarity of their 16srDNA sequence was above 99%, which showed that they were the same kind of facultative anaerobic bacteria-Escherichia coli.3. The growth curve test on the two isolated anaerobic bacteria showed that the logarithmic phase of the Klebsiella pneumoniae is during the first 1-8h, the stable period is during the secend 8-14h, after 14h it entered the decline phase. For the Escherichia coli the logarithmic phase is during 1-4h, the stable period is 4-14h, the same as the Klebsiella pneumoniae, after 14h it entered the decline phase. The two bacteria had the same decline phase start, but their logarithmics phases and stable periods had no significant difference..4. The anaerobic fluidized bed bioreactor was developed by our lab. It got rid of the small-scale hydrogen production unit such as a laboratory, but produced hydrogen with the hydrogen bacteria and the raw materials in a large-scale recycling way. The anaerobic environment and the constant temperature can provide a more stable working environment for the hydrogen production by fermentating anaerobically. The straw material can directly and easily be put into the reactor to feed the bacteria for hydrogen producting.5. The sucrose was used as the inducing substance, and the sweet sorghum was used as the raw material. They were made developed in the anaerobic fluidized bed bioreactor to measure the performance of the bacterial hydrogen production. The results showed that the two types of bacteria not only can produce hydrogen, but also form as the white granule on the carbon in the reactor. After the granule formed, while maintaining the hydraulic retention time (HRT), after 3-5 d the hydrogen was produced. And both the using sucrose phase and the using sweet sorghum stalk phase will produce hydrogen. In the stage using the sweet sorghum stalk, the hydrogen production was significantly higher than the hydrogen production using the sucrose phase.In the evaluation of hydrogen production efficiency, the controlled temperature of the reactor was 37℃. The hydraulic retention time (HRT) was reduced from 9.3 h to 4.6 h after 14 d, The pH value of the hydrogen production base was 5.8-6.5. The highest content of hydrogen by Klebsiella pneumoniae during the whole experiment process could reach up to 28%, the Escherichia coli could reach up to 31.6%.
Keywords/Search Tags:biohydrogen production, Klebsiella pneumoniae, Escherichia coli, bioreactor, straw
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