The high concentrations of CO (toxic) and CO2 (greenhouse gases) in blast furnace gas (a by-product of steelworks) reflect its low calorific value. In this study, anaerobic granular sludge was used to convert carbon from blast furnace gas to methane via exogenous hydrogen addition. The inhibition of methane production by CO partial pressure (P CO) was found to start from 0.4 atm. The intermediate metabolites from CO to methane including acetate, propionate, and H2 accumulated at higher CO concentrations in the presence of 2-bromoethanesulfonic acid. After the introduction of H2 and blast furnace gas, although the hydrogen partial pressure (P H2 ) up to 1.54 atm resulted in the maximum CH4 yield, the whole system was not stable due to the accumulation of a large amount of volatile fatty acids. The optimum P H2 on CH4 production from the simulated blast furnace gas, 5.32 mmol g-1 VSS, was determined at 0.88 atm in this study.
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