Biological hydrogen production on acetate in continuous panel photobioreactors using rhodobacter capsulatus

Androga, Dominic Deo
Photobiological hydrogen production from organic acids occurs in the presence of light and under anaerobic conditions. Stable and optimized operation of the photobioreactors is the most challenging task in the photofermentation process. The main aim of this study was to achieve in long term, a stable and high hydrogen production on acetate, using the photosynthetic bacteria Rhodobacter capsulatus in continuous panel photobioreactors. Rhodobacter capsulatus (DSM 1710), heat adapted Rhodobacter capsulatus (DSM 1710) and Rhodobacter capsulatus YO3 (Hup-), a mutant strain, were tested in outdoor conditions, under natural sunlight between September-December, 2008 in Ankara, Turkey. Defined culture medium containing acetate (40 mM) and glutamate (2 mM) and a dilution rate of 0.8 l/ day were used. Steady hydrogen production (0.4 mmol H2/lc.h) was obtained using the Rhodobacter capsulatus YO3 (Hup-) mutant strain that was continuously operated for 69 days, but the cell concentration could not be kept at a steady value. Further efforts were focused on achieving stable biomass concentration by optimizing the feed composition. Stable biomass (0.40 gdcw/lc) and high hydrogen productivity (0.8 mmol H2/lc.h) were achieved using feed media containing 40 mM acetate and 4 mM glutamate with a 10% (v/v) feed rate. Moreover, the EU project HYVOLUTION aims to combine dark fermentation and photofermentation process for the conversion of biomass to hydrogen. Effluents from the dark fementation contain high amount of ammonium, which inhibits phototrophic hydrogen production. After treatment it has been concluded that Gördes clinoptilolite zeolite effectively removes ammonium ion from the dark fermenter effluent of molasses.
Citation Formats
D. D. Androga, “Biological hydrogen production on acetate in continuous panel photobioreactors using rhodobacter capsulatus,” M.S. - Master of Science, Middle East Technical University, 2009.