BIOREACTOR DESIGN STUDIES FOR A NOVEL HYDROGEN-PRODUCING BACTERIUM

Carbon monoxide (CO) can be metabolized by a number of naturally occurring microorganisms along with water to produce hydrogen (H2) and carbon dioxide (CO2). NREL researchers have isolated a number of bacteria that perform this so-called water-gas shift reaction at ambient temperatures. We have performed experiments to measure the rate of biological CO conversion and H2 production in a trickle bed reactor (TBR). The reactor support material has a significant effect on the mass transfer coefficient, which in turn controls the overall reactor performance for this mass transfer-limited reaction. A simple reactor model taken from the literature is used to quantitatively compare the relative performance of the different support materials, including one support material tested at two different TBR sizes (1-L and 5-L). A TBR bioreactor was used to condition water-scrubbed synthesis gas from a biomass gasifier, and was unaffected by the presence of low concentrations of aromatic compounds over the course of the weeklong test