The Effect of Microbial Community Composition on a Pilot-Scale Sequencing Hydrogen/Methane Producing System
| Autor: | Yi-Cheng He, 何翊誠 |
|---|---|
| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 In recent years, theory of dark fermentation biohydrogen production has been well established. Focuses have been shifted to pilot-scale reactor operation as well as to increase methane production using effluent of biohydrogen reactor. System performance strongly correlates to the interaction of microbial community within the reactor. In dark fermentation system, Clostridium sp. is the predominant microorganism responsible for hydrogen production and methanogens is responsible for methane production. However, the microorganism community changes constantly as the operation condition differs. In order to understand the relationship between system performance and microorganism community, molecular biological techniques, including PCR-DGGE, cloning and real-time PCR were applied on sludge samples collected from a pilot-scale sequencing hydrogen/methane producing system operated by Fen Chia University. According to the results from PCR-DGGE, C. butyricum and C. tyrobutyricum were the major clostridia, which is responsible for the biohydrogen production. Others existed microorganisms included Klebsiella pneumonia, Clostridiaceae bacterium, Desulfovibrio sp., Dialister succinatiphilus, Bifidobacterium minimum, and Ruminococcus sp. Amount of Clostridium sp. cell count was around 105-106 gene copies/mL and the rest is about 104-106 gene copies/mL. Hydrogen production rate correlated with the number of Clostridium sp. On the late operational stage, the number of Clostridium sp. decrease to less than 105 gene copies/mL and the number of Klebsiella sp. cell count was higher than Clostridium sp. in agreement with a decreasing of hydrogen production. Clearly, the interaction of different microorganisms strongly affect the performance of biohydrogen production system. As for the methane tank, production rate increased as the HRT decreased. Composition of methanogens changed as well. The results showed that the Methanosarcina mazei and Methanosaeta harundinacea were the predominant methanogens when operated at HRT 67hr. No significant change on the methanogens number was observed for the first 79 days of operation. The amount of methanogens cell count was around 104-105 gene copies/mL. When changed to HRT 24hr, the number of methanogens decrease to less than 104 gene copies/mL but rebounded to the previous cell counts immediately. This is a demonstration that even though possible washed out happened, the system could be re-established in no time. In the E / PMA-PCR experiments on bacteria activity, the results showed that EMA and PMA can be used in hydrogen production system to reveal microbial activity. Furthermore, storage could be a strong factor on misleading the bacterial activity results. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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