Hydrogen Production with Immobilized Cells
碩士 === 逢甲大學 === 化學工程學所 === 90 === ABSTRACT Municipal sewage sludge was immobilized to produce hydrogen gas under anaerobic conditions. Cell immobilization was essentially achieved by gel entrapment approaches, which were physically or chemically modified by addition of activated carbon (AC), polyure...
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2002
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碩士 === 逢甲大學 === 化學工程學所 === 90 === ABSTRACT
Municipal sewage sludge was immobilized to produce hydrogen gas under anaerobic conditions. Cell immobilization was essentially achieved by gel entrapment approaches, which were physically or chemically modified by addition of activated carbon (AC), polyurethane (PU) and acrylic latex plus silicone (ALSC). The performance of hydrogen fermentation with a variety of immobilized-cell systems was assessed to identify the optimal type of immobilized cells for practical uses.
Using sucrose as the limiting carbon source, hydrogen production was more efficient with the immobilized-cell system than with the suspended-cell system, while in both cases, the predominant soluble metabolites were butyric acid and acetic acid. Addition of activated carbon into alginate gel (denoted as CA/AC cells) enhanced the hydrogen production rate ( ) and substrate-based yield ( ) by 70% and 52%, respectively, over the conventional alginate-immobilized cells. Further supplementation of polyurethane or acrylic latex/silicone increased the mechanical strength and operation stability of the immobilized cells, but caused a decrease in the hydrogen production rate.
Kinetic studies show that the dependence of specific hydrogen production rates on the concentration of limiting substrate (sucrose) can be described by Michaelis-Menten model with good agreement. The maximum hydrogen production rate ( ) estimated from the model decreased in the order of CA/AC cells > ALSC cells > PU cells. Meanwhile, CA/AC also had the highest value of dissociation constant (Km), followed by PU and ALSC cells. The kinetic analysis suggests that CA/AC cells may contain higher concentration of active biocatalysts for hydrogen production, while PU and ALSC cells had better affinity to the substrate. Acclimation of the immobilized cells by repeated hydrogen fermentation with sucrose led to a remarkable enhancement in with a twenty-five fold increase for CA/AC and ca. 10-15 fold increases for PU and ALSC cells. However, the ALSC cells were found to have better durability than PU and CA/AC cells as they allowed stable hydrogen production for over 24 repeated runs.
Acclimation of the immobilized cells by repeated hydrogen fermentation with sucrose show that the ALSC cells had better mechanical strength and operation stability. Using the ALSC cells as the bed material, the experiments were carried out in a three-phase fluidized bed reactor with hydrogen fermentation. Two important properties show in the experiment results: one is hydrodynamic, and the other is hydrogen fermentation.
In hydrodynamic: Under a steady state of biogas production rate there are three flow regimes that varied with different operating liquid velocities such as plug-flow, slugging and free bubbling. The technique of pressure fluctuation analysis was used to analyze the hydrodynamic properties in this three-phase fluidized bed. The biogas production rate was Ug = 0.52 ml/s, and the liquid velocity was Uo = 0.85 cm/s, this being the transition state. Under Uo = 0.85 cm/s there is a heterogeneous fluidized bed, while above this liquid velocity, the bed is homogeneous.
In hydrogen fermentation: The bed expansion was 30%, the reaction temperature was 35℃, and the liquid velocity was Uo = 1.38 cm/s. While the hydraulic retention time (HRTe) of sucrose was decreased from 6h to 2h, the hydrogen production rate was increased. When HRTe was further decreased to 1h, but the hydrogen production rate was decreased sharply. In this situation, the temperature of the fluidized bed was increased to 70℃ for thermal treatment. After 30 minutes, and the HRTe was back to 2h, the hydrogen production rate was regained rapidly. The ALSC cells had the best specific production rate (υH2 ) and substrate-based hydrogen yield (YH2/sucrose) of 2.92 L/h-g VSS and 2.67 mol H2/ mol sucrose, respectively. The composition of soluble metabolites of Butyric acid (HBu) was produced significantly during fluidized bed hydrogen fermentation. The result is similar to the batch hydrogen fermentation. As the result, it seems to be available to scale up from batch system to continuous fluidized bed.
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author2 |
Shu-Yii Wu |
author_facet |
Shu-Yii Wu Chi-Num Lin 林祺能 |
author |
Chi-Num Lin 林祺能 |
spellingShingle |
Chi-Num Lin 林祺能 Hydrogen Production with Immobilized Cells |
author_sort |
Chi-Num Lin |
title |
Hydrogen Production with Immobilized Cells |
title_short |
Hydrogen Production with Immobilized Cells |
title_full |
Hydrogen Production with Immobilized Cells |
title_fullStr |
Hydrogen Production with Immobilized Cells |
title_full_unstemmed |
Hydrogen Production with Immobilized Cells |
title_sort |
hydrogen production with immobilized cells |
publishDate |
2002 |
url |
http://ndltd.ncl.edu.tw/handle/39669706796211663088 |
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AT chinumlin hydrogenproductionwithimmobilizedcells AT línqínéng hydrogenproductionwithimmobilizedcells AT chinumlin gùdìnghuàxìbāochǎnqīng AT línqínéng gùdìnghuàxìbāochǎnqīng |
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ndltd-TW-090FCU050630112015-10-13T17:39:43Z http://ndltd.ncl.edu.tw/handle/39669706796211663088 Hydrogen Production with Immobilized Cells 固定化細胞產氫 Chi-Num Lin 林祺能 碩士 逢甲大學 化學工程學所 90 ABSTRACT Municipal sewage sludge was immobilized to produce hydrogen gas under anaerobic conditions. Cell immobilization was essentially achieved by gel entrapment approaches, which were physically or chemically modified by addition of activated carbon (AC), polyurethane (PU) and acrylic latex plus silicone (ALSC). The performance of hydrogen fermentation with a variety of immobilized-cell systems was assessed to identify the optimal type of immobilized cells for practical uses. Using sucrose as the limiting carbon source, hydrogen production was more efficient with the immobilized-cell system than with the suspended-cell system, while in both cases, the predominant soluble metabolites were butyric acid and acetic acid. Addition of activated carbon into alginate gel (denoted as CA/AC cells) enhanced the hydrogen production rate ( ) and substrate-based yield ( ) by 70% and 52%, respectively, over the conventional alginate-immobilized cells. Further supplementation of polyurethane or acrylic latex/silicone increased the mechanical strength and operation stability of the immobilized cells, but caused a decrease in the hydrogen production rate. Kinetic studies show that the dependence of specific hydrogen production rates on the concentration of limiting substrate (sucrose) can be described by Michaelis-Menten model with good agreement. The maximum hydrogen production rate ( ) estimated from the model decreased in the order of CA/AC cells > ALSC cells > PU cells. Meanwhile, CA/AC also had the highest value of dissociation constant (Km), followed by PU and ALSC cells. The kinetic analysis suggests that CA/AC cells may contain higher concentration of active biocatalysts for hydrogen production, while PU and ALSC cells had better affinity to the substrate. Acclimation of the immobilized cells by repeated hydrogen fermentation with sucrose led to a remarkable enhancement in with a twenty-five fold increase for CA/AC and ca. 10-15 fold increases for PU and ALSC cells. However, the ALSC cells were found to have better durability than PU and CA/AC cells as they allowed stable hydrogen production for over 24 repeated runs. Acclimation of the immobilized cells by repeated hydrogen fermentation with sucrose show that the ALSC cells had better mechanical strength and operation stability. Using the ALSC cells as the bed material, the experiments were carried out in a three-phase fluidized bed reactor with hydrogen fermentation. Two important properties show in the experiment results: one is hydrodynamic, and the other is hydrogen fermentation. In hydrodynamic: Under a steady state of biogas production rate there are three flow regimes that varied with different operating liquid velocities such as plug-flow, slugging and free bubbling. The technique of pressure fluctuation analysis was used to analyze the hydrodynamic properties in this three-phase fluidized bed. The biogas production rate was Ug = 0.52 ml/s, and the liquid velocity was Uo = 0.85 cm/s, this being the transition state. Under Uo = 0.85 cm/s there is a heterogeneous fluidized bed, while above this liquid velocity, the bed is homogeneous. In hydrogen fermentation: The bed expansion was 30%, the reaction temperature was 35℃, and the liquid velocity was Uo = 1.38 cm/s. While the hydraulic retention time (HRTe) of sucrose was decreased from 6h to 2h, the hydrogen production rate was increased. When HRTe was further decreased to 1h, but the hydrogen production rate was decreased sharply. In this situation, the temperature of the fluidized bed was increased to 70℃ for thermal treatment. After 30 minutes, and the HRTe was back to 2h, the hydrogen production rate was regained rapidly. The ALSC cells had the best specific production rate (υH2 ) and substrate-based hydrogen yield (YH2/sucrose) of 2.92 L/h-g VSS and 2.67 mol H2/ mol sucrose, respectively. The composition of soluble metabolites of Butyric acid (HBu) was produced significantly during fluidized bed hydrogen fermentation. The result is similar to the batch hydrogen fermentation. As the result, it seems to be available to scale up from batch system to continuous fluidized bed. Shu-Yii Wu 吳石乙 2002 學位論文 ; thesis 94 zh-TW |