Effect of Localized Temperature Difference on Hydrogen Fermentation

In a lab-scale bioreactor system, (20 L of effective volume in our study) controlling a constant temperature inside bioreactor with a total volume 25 L is a simple process, whereas it is a complicated process in the actual full-scale system. There might exist a localized temperature difference insid...

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Autores principales: Seongwon Im, Mo-Kwon Lee, Alsayed Mostafa, Om Prakash, Kyeong-Ho Lim, Dong-Hoon Kim
Formato: article
Lenguaje:EN
Publicado: MDPI AG 2021
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Acceso en línea:https://doaj.org/article/38b02427e7084e7fa145c7c3c007e63c
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Sumario:In a lab-scale bioreactor system, (20 L of effective volume in our study) controlling a constant temperature inside bioreactor with a total volume 25 L is a simple process, whereas it is a complicated process in the actual full-scale system. There might exist a localized temperature difference inside the reactor, affecting bioenergy yield. In the present work, the temperature at the middle layer of bioreactor was controlled at 35 °C, while the temperature at top and bottom of bioreactor was controlled at 35 ± 0.1, ±1.5, ±3.0, and ±5.0 °C. The H<sub>2</sub> yield of 1.50 mol H<sub>2</sub>/mol hexose<sub>added</sub> was achieved at ±0.1 and ±1.5 °C, while it dropped to 1.27 and 0.98 mol H<sub>2</sub>/mol hexose<sub>added</sub> at ±3.0 and ±5.0 °C, respectively, with an increased lactate production. Then, the reactor with automatic agitation speed control was operated. The agitation speed was 10 rpm (for 22 h) under small temperature difference (<±1.5 °C), while it increased to 100 rpm (for 2 h) when the temperature difference between top and bottom of reactor became larger than ±1.5 °C. Such an operation strategy helped to save 28% of energy requirement for agitation while producing a similar amount of H<sub>2</sub>. This work contributes to facilitating the upscaling of the dark fermentation process, where appropriate agitation speed can be controlled based on the temperature difference inside the reactor.