抄録
Thermococcus onnurineus, which had been isolated from a deep-sea hydrothermal vent area in 2002, was known to be able to grow on carbon monoxide (CO) evolving hydrogen (H2) via water-gas shift (WGS) reaction (CO + H2O → CO2 + H2O). In this study, a biological continuous process was developed to produce H2 from CO. For this purpose, continuous fermentation of T. onnurineus was carried out in a 2.5 L stirred tank bioreactor with varying dilution rate, CO supply rate, or agitation speed. It was observed that
both cell growth and H2 production rate (HPR) were linearly correlated with dilution rate unless CO was not limited. HPR has also been observed to increase linearly with CO supply rate or agitation speed, mainly due to an increase of gas-liquid mass transfer. Based on the lab-scale results, the pilot study was performed in a 1,000 L gas-lift type bioreactor using CO-containing industrial off-gas as a raw material for CO. As a results of continuous cultivation of T. onnurineus on steel mill by-product gas, HPR reached a maximum value of 250 mmol/L/h, which corresponds to a daily production of 50 Nm3.
