Bioconversion of Waste Gases into Biofuel via Fermentation in a Continuous Stirred Tank Bioreactor

Biological hydrogen production was carried out in a continuous stirred tank bioreactor. A photosynthetic bacterium, Rhodospirillum rubrum, was used as biocatalyst to oxidize carbon monoxides in the waste gas generated from biomass in a gasification process. The fresh liquid media was supplied for microbial growth which contained sodium acetate as carbon source at initial concentration of 4 gL-1. The optimum media space velocity or the suitable ratio of liquid flow rate to the reactor volume (F/VL) was 0.02 h-1. At the steady state condition, the concentration of acetate was independent of the dilution rate and it was approximately 1.5 gL-1. The average cell dry weight in the fermentation broth was at satisfactory concentration, approximately 3.4 gL-1 with dilution rate at 0.55 mL min-1. The maximum value of KLa and CO conversion were about 58 h-1 and 80%, respectively, with agitation speed at 500 rpm and gas flow rate at 14 mL min-1. At this condition, the maximum yield of hydrogen production was 0.82 mmol H2 mmol-1 CO.