초록
<P><B>Abstract</B></P> <P> <I>Chlorella</I> sp. biomass was used as the sole substrate for the production of hydrogen and methane through integrated dark fermentation (DF) and photo-fermentation (PF), and DF and anaerobic digestion (AD) processes. Prior to use in fermentations, the biomass was pretreated by acid-hydrothermal method, which yielded a maximum reducing sugar yield of 162.9 ± 4.2 mg g-biomass<SUP>−1</SUP>. The use of the microalgal hydrolysate to produce hydrogen by DF gave a hydrogen yield (HY) of 47.2 ± 1.1 mL g-volatile-solids<SUP>−1</SUP> (VS). The subsequent use of the hydrogenic effluent in PF gave a HY of 125.0 ± 1.5 mL g-VS<SUP>−1</SUP>, while AD of the hydrogenic effluent gave a methane yield of 152.8 ± 1.3 mL g-VS<SUP>−1</SUP>. The total energy yield attained by the use of DF alone, the integrated DF-PF, and DF-AD processes were 0.51, 1.86 and 5.98 kJ g-VS<SUP>−1</SUP>, respectively. These results indicate that the integrated DF-AD process was effective in recovering energy from <I>Chlorella</I> sp. biomass. However, an energy balance analysis indicated that the process was not energetically feasible due to the high energy demand for the acid-hydrothermal pretreatment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Integrated processes improve energy recovery from <I>Chlorella</I> sp. biomass. </LI> <LI> Dark fermentation (DF) of the biomass gave an energy yield (EY) of 0.51 kJ g-VS<SUP>−1</SUP>. </LI> <LI> Integrated DF-photo fermentation (PF) process gave an EY of 1.86 kJ g-VS<SUP>−1</SUP>. </LI> <LI> Integrated DF-anaerobic digestion (AD) gave an EY of 5.98 kJ g-VS<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>