博士 / 逢甲大學 / 化學工程學所 / 98 / The fermentation of the organic waste to produce hydrogen, one of the clean and renewable energies, is an innovative technology for sustainable energy. The key technology of hydrogen production from glucose and xylose with seacoast sludge was studied in this thesis, expecting the results will be used for reference on the system establishment of hydrogen production from cellulosic materials in the future.
First, the results of batch experiments showed that the optimal cultivated factors of seacoast sludge for hydrogen production from sucrose were 37oC and pH 5.5, respectively. The continuous flow stirred tank reactors (CSTR) were used to verify the pH effect on continuous hydrogen production from sucrose, the results suggested that the optimal pH value was 5.75. The effect of hydraulic retention time (HRT) on hydrogen production from sucrose with a CSTR reactor was investigated. The results showed that sludge granulation occurred at HRT 4 h and favored H2 production, obtaining a H2 production rate (HPR) and yield of 1.11 mol/L/d and 3.82 mol H2/mol sucrose, respectively. The granular sludge system could be stably carried out at a low HRT of 0.5 h and the HPR and HY reached 6.72 mol/L/d and 3.16 mol H2/mol sucrose, respectively. The HRT effects on H2 production were studied using both CSTR and AGSB (agitated granular sludge bed) bioreactors. The results showed that the optimal H2 production efficiency was occurred at HRT 6 and 2 h, respectively, giving a HPR of 0.688 and 1.718 mol/L/d. The analytical results of microbial community structure using DGGE (denaturing gradient gel electrophoresis) presented that the predominant H2-producing microorganisms were Clostridium pasteurianum and Clostridium butyricum in glucose-feeding CSTR reactor at HRT 12?{4 h.
Second, the hydrogen production from xylose with seacoast sludge was explored. The results of batch experiments showed that the optimal environmental factors for H2 production were 37oC and pH 5.5, respectively. A CSTR system was used to verify the pH effect on continuous H2 production from xylose, the results suggested that the optimal pH value was 5.75. The effects of substrate concentration and HRT on H2 production from xylose with a CSTR reactor were investigated. The results showed that the most suitable substrate concentration was 15 g COD/L, getting a HPR and HY of 0.270 mol/L/d and 1.73 mol H2/mol xylose, respectively. The substrate utilization was only 66% when substrate concentration was 25 g COD/L, resulting in decreasing H2 production efficiency. The results of various HRT tests under substrate concentration 20 g COD/L showed that the optimal H2 production efficiency occurred at HRT 12 h, obtaining a HPR and HY of 0.278 mol/L/d and 1.39 mol H2/mol xylose, respectively. The analytical results of microbial community structure showed that the predominant H2-producing microorganisms were Clostridium sp. and Klebsiella sp. at HRT 12 h. The AGSB bioreactor was used to enhance the efficiency of H2 production from xylose. The results showed that the HPR and HY were 0.488 mol/L/d and 1.13 mol H2/mol xylose, respectively, at a HRT of 6 h.
Third, the cofermentation of glucose and xylose to hydrogen was investigated. For the CSTR system, the effects of pH, glucose/xylose (C6/C5) ratio, and HRT on H2 production were explored at substrate concentration of 20 g COG/L. The results indicated that the optimal operation conditions were pH 5.75, C6/C5 ratio 50/50, and HRT 12 h, respectively. The HPR and HY were 0.299 mol/L/d and 9.29 mmol H2/g COD, respectively. For the experiments of various C6/C5 ratios, xylose utilization decreased with increasing C6/C5 ratio. This suggested that the presence of glucose would reduce the utilization of xylose. For the experiments of various HRTs (C6/C5 = 50/50), xylose utilization decreased with decreasing HRT. Thus, the key factor of cofermentation with glucose and xylose was enhancement of xylose utilization. The analytical results of microbial community structure showed that the predominant H2-producing microorganisms were Clostridium sp. and Klebsiella sp.. For the AGSB system (C6/C5 = 50/50), sludge granulation occurred at HRT 6 h. Although HPR increased with decreasing HRT, HY decreased with decreasing HRT. The HPR and HY were 1.08 mol/L/d and 5.31 mmol H2/g COD, respectively, at a HRT of 2 h.
Final, a CSTR bioreactor of pilot scale with a working volume of about 400 L was used to carry out H2 production from sucrose. The pilot system could start up successfully at a substrate concentration of 20 g COD/L and HRT of 8 h. The optimal operation conditions were substrate concentration 30 g COD/L and HRT 6 h, obtaining a HPR and HY of 1.18 mol/L/d and 3.84 mol H2/mol sucrose, respectively.
| Identifer | oai:union.ndltd.org:TW/098FCU05063066 |
| Date | January 2010 |
| Creators | Lee-hao Yang, 楊立豪 |
| Contributors | none, 林屏杰 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 210 |
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