초록
<P><B>Abstract</B></P> <P>Biohydrogen production through dark fermentation is a promising technology for generating renewable energy, while using microalgal biomass as a third generation feedstock can further increase the sustainability of the process. In the present study, <I>Scenedesmus obliquus</I> was used as model microalga substrate for studying the impact of operational parameters in batch dark fermentation trials using a strain of <I>Enterobacter aerogenes</I> bacteria.</P> <P>(i) The initial gas-liquid ratio in the bioreactor (from 1.3 to 8.2) was tested, resulting in higher bioH<SUB>2</SUB> yields for ratios above 5.</P> <P>(ii) Different bacterial growth, inoculation procedures and fermentation media were tested in combined experiments. The best conditions were chosen by maximising bioH<SUB>2</SUB> yield and minimising production time and costs.</P> <P>(iii) The autoclave sterilization effect on sugar extraction and bioH<SUB>2</SUB> yield was tested for different microalga concentrations (2.5–50 g/L) with best results attained for 2.5 g/L (81.2% extraction yield, 40.9 mL H<SUB>2</SUB>/g alga).</P> <P>For the best operational conditions, fermentation kinetics were monitored and adjusted to the Modified Gompertz model, with <I>t</I> <SUB> <I>95</I> </SUB> (time required for bioH<SUB>2</SUB> production to attain 95% of the maximum yield) below 4.5 h. The maximum hydrogen production was higher when using wet algal biomass enabling the energy consuming biomass drying step to be skipped.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Scenedesmus obliquus</I> was used as feedstock for bioH<SUB>2</SUB> production by <I>Enterobacter aerogenes</I>. </LI> <LI> Initial gas-liquid ratios above 5 in the bioreactor provide higher bioH<SUB>2</SUB> yields. </LI> <LI> Pre-inoculum and inoculation procedures significantly affect bioH<SUB>2</SUB> yields. </LI> <LI> Autoclave sterilization can have effect on the sugar extraction from <I>S. obliquus</I> biomass. </LI> <LI> BioH<SUB>2</SUB> production kinetics revealed that stationary phase can be achieved under 4.5 h. </LI> </UL> </P>