In that project, it
was found that the optimum bioreactor design for the dark
fermentation is one combining moving-bed and trickling-bed
operation. For the photofermentation, two modular designs of the
bioreactor were tested, one employing modules made of low-
density polyethylene tubes and another one in which modules
were composed of flat panels with transparent plastic walls.
Furthermore gas-upgrading technology options were studied and
their characteristics were evaluated from the point of view of po-
tential applications in hydrogen production plants based on the
fermentative conversion of biomass. It was found that vacuum
swing adsorption (VSA) employing carbon dioxide adsorption on
molecular sieve is a good choice for low investment, small-scale
plants.