초록
<P><B>Abstract</B></P> <P>The effect of different inorganic acids viz., HNO<SUB>3</SUB>, HCl, H<SUB>2</SUB>SO<SUB>4</SUB> and H<SUB>3</SUB>PO<SUB>4</SUB> on inoculum pretreatment to selectively enrich hydrogen (H<SUB>2</SUB>) producing acidogenic bacteria was evaluated in anaerobic sequencing batch bioreactors. Relative positive efficiency of HNO<SUB>3</SUB> pretreated consortia in enhancing H<SUB>2</SUB> production (11.85molH<SUB>2</SUB>/kgCOD<SUB>R</SUB>) was noticed compared to other acids (HCl, 5.64molH<SUB>2</SUB>/kgCOD<SUB>R</SUB>; H<SUB>2</SUB>SO<SUB>4</SUB>, 7.65molH<SUB>2</SUB>/kgCOD<SUB>R</SUB>; H<SUB>3</SUB>PO<SUB>4</SUB>, 6.90molH<SUB>2</SUB>/kgCOD<SUB>R</SUB>) and untreated-parent consortia (control, 6.80molH<SUB>2</SUB>/kgCOD<SUB>R</SUB>). On the contrary, substrate degradation (COD removal) was higher with the control operation (<I>ξ</I> <SUB>COD</SUB>, 66.3%; substrate degradation rate (SDR), 1.42kgCOD<SUB>R</SUB>/m<SUP>3</SUP>-day) compared to pre-treated culture. HNO<SUB>3</SUB> pre-treatment resulted in a shift in the fermentation pathway towards more acetic acid production, while other acid pretreatment and untreated culture showed mixed type fermentation (acetic, butyric, propionic acids). The bio-electrochemical analysis and dehydrogenase activity supported the biocatalyst performance after HNO<SUB>3</SUB> pretreatment with specific enrichment of <I>Firmicutes</I> and <I>Bacillus</I>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Selective enrichment of biocatalyst by different inorganic acids was studied. </LI> <LI> Acetate–butyrate type fermentation was observed with HNO<SUB>3</SUB> treated culture. </LI> <LI> HNO<SUB>3</SUB> pretreated consortia showed relatively more H<SUB>2</SUB> production. </LI> <LI> Dehydrogenase activity and bio-electro kinetics correlated well. </LI> <LI> Microbial diversity illustrated the enrichment of <I>Firmicutes</I>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>