초록
<P><B>Abstract</B></P> <P>To investigate the effects of aeration on hydrogen-producing granular system, experiments were performed in two laboratory-scale anaerobic internal circulation hydrogen production (AICHP) reactors. The preliminary experiment of Reactor 1 showed that direct aeration was beneficial to enhancing hydrogen production. After the direct aeration was implied in Reactor 2, hydrogen production rate (HPR) and hydrogen content were increased by 100% and 60%, respectively. In addition, mixed-acid fermentation was transformed into typical ethanol-type fermentation (ETF). Illumina MiSeq sequencing shows that the direct aeration did not change the species of hydrogen-producing bacteria but altered their abundance. Hydrogen-producing bacteria and ethanol-type fermentative bacteria were increased by 24.5% and 146.3%, respectively. <I>Ethanoligenens</I> sp. sharply increased by 162.2% and turned into predominant bacteria in the system. These findings indicated that appropriate direct aeration might be a novel and promising way to obtain ETF and enhance hydrogen production in practical use.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The direct aeration transformed mixed-acid fermentation into typical ETF. </LI> <LI> HPR and hydrogen content increased by around 100% and 60%, respectively. </LI> <LI> The total amount of ethanol-type fermentative bacteria was increased by 146.3%. </LI> <LI> <I>Ethanoligenens</I> sp. increased by 162.2% and became the main fermentative bacteria. </LI> <LI> Direct aeration could be a novel way of obtaining ETF with high HPR. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>