초록
<P><B>Abstract</B></P> <P>This study was the first attempt to investigate the effect of hydrothermal treatment on energy recovery of <I>Chlorella</I> sp. via two-stage anaerobic fermentation (TSAF). A maximum biohydrogen yield of 8.29 ± 0.33 mLH<SUB>2</SUB>/gVS was achieved at the control group (CG), and a highest biomethane yield of 434.38 ± 5.72 mLCH<SUB>4</SUB>/gVS was obtained for the group at the weakest hydrothermal treatment severity (HTS) (2.49). Compared with CG, the energy recovery was increased by 12.78% for the group at HTS 2.49, reduced by 6.05% and 32.09% for groups at HTS 4.06 and 5.21, respectively. Compared to single anaerobic digestion, TSAF significantly increased the energy recovery by 22.23–146.78%. 5-HMF and furfural were degraded by 17.65–71.08% and 46.58–82.20%, respectively, after first-stage biohydrogen fermentation. The analysis of microbial structure revealed that <I>Peptococcaceae</I> and <I>Desulfovibrio</I> related to inhibitors degradation were enriched with increasing HTS during first-stage fermentation. During the second-stage biomethane fermentation, the family <I>Enterobacteriaceae</I> was reduced as a symbiosis with hydrogenotrophic methanogens, accompanied with a decrease of <I>Methanobacteriaceae</I>. In comparison, the family <I>Methanosaetaceae</I> and <I>Methanosarcinaceae</I> belonging to acetoclastic methanogens, were remarkably increased due to the VFAs-rich effluents.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Algae two-stage fermentation with hydrothermal treatment was firstly studied. </LI> <LI> The weakest severity at 2.49 got the highest CH<SUB>4</SUB> (434 mL) and energy recovery (64%). </LI> <LI> 5-HMF was degraded by 17–71% after first-stage biohydrogen fermentation. </LI> <LI> Two-stage increased energy recovery by 22–146% than anaerobic digestion. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>