초고온성 고세균 Thermococcus onnurineus에 의한 제철소 부생가스로부터 바이오수소 연속생산 실증연구

Abstract

Thermococcus onnurineus, which had been isolated from a deep-sea hydrothermal vent area in the PACMANUS field in 2002, has been recently found to be able to grow on carbon monoxide (CO) producing hydrogen (H2) via water-gas shift (WGS) reaction. In this study, using steel mill by-product gas as a CO source, the mass production of bio-H2 was demonstrated by long-term continuous culture of T. onnurineus in a 1,000L gas-lift bio-reactor equipped with six external gas-liquid mixers. Of the steel mill by-product gases, Linz-Donawitz gas (LDG) containing ca. 55% of CO was used throughout the experiment. The continuous cultivation of T. onnurineus was carried out for 40 days varying gas supply rate of LDG or gauge pressure in a reactor at fixed dilution rate of 0.042 h-1. As a result, it was observed that both the cell growth and the volumetric H2 production rate (HPR) were increased depending on the LDG supply rate mainly due to the increase of gas-liquid mass transfer rate. Whereas, the CO conversion showed an inversely proportional relationship to the LDG supply rate probably due to the reduced residence time of CO by the increased superficial velocity of gas. The gauge pressure in a reactor was also turned out to be a key process variable in WGS activity of T. onnurineus showing the positive effect in cell growth, HPR and CO conversion. At LDG supply rate of 0.2 vvm and gauge pressure of 1.5 bar, the cell concentrationtion. In this study, using steel mill by-product gas as a CO source, the mass production of bio-H2 was demonstrated by long-term continuous culture of T. onnurineus in a 1,000L gas-lift bio-reactor equipped with six external gas-liquid mixers. Of the steel mill by-product gases, Linz-Donawitz gas (LDG) containing ca. 55% of CO was used throughout the experiment. The continuous cultivation of T. onnurineus was carried out for 40 days varying gas supply rate of LDG or gauge pressure in a reactor at fixed dilution rate of 0.042 h-1. As a result, it was observed that both the cell growth and the volumetric H2 production rate (HPR) were increased depending on the LDG supply rate mainly due to the increase of gas-liquid mass transfer rate. Whereas, the CO conversion showed an inversely proportional relationship to the LDG supply rate probably due to the reduced residence time of CO by the increased superficial velocity of gas. The gauge pressure in a reactor was also turned out to be a key process variable in WGS activity of T. onnurineus showing the positive effect in cell growth, HPR and CO conversion. At LDG supply rate of 0.2 vvm and gauge pressure of 1.5 bar, the cell concentration