초록
<P><B>Abstract</B></P> <P>An innovative multistage anaerobic hythane reactor (MAHR) which combines an internal biofilm (M<SUB>H</SUB>) and an external up-flow sludge blanket (M<SUB>M</SUB>) was proposed to produce biohythane from wastewater. The effect of pH on its biohythane production and microbial diversity was performed. Results showed that the maximum hydrogen production rate (4.900 L/L/d) was achieved at a pH of 6.0, in comparison to a maximum methane production rate of 10.271 L/L/d at a pH of 6.5. In addition, a suitable hythane (H<SUB>2</SUB>/(H<SUB>2</SUB>+CH<SUB>4</SUB>) of 16.06%) production can be achieved in M<SUB>H</SUB> after the initial pH was adjusted from 7.0 to 6.5, and a relatively high methane yield (271.34 mL CH<SUB>4</SUB>/gCOD) was obtained in M<SUB>M</SUB>. Illumina Miseq sequencing results revealed that decreasing pH led to an increase of the acidogenesis families (<I>Eubacteriaceae</I>, <I>Ruminococcaceae</I>) in M<SUB>H</SUB> and an increase of hydrogenotrophic methanogens (<I>Methanobacteriaceae</I>) in M<SUB>M</SUB>. The <I>Methanosaetaceae</I> gradually occupied a major portion after a long period of recovery. This work demonstrated the unique advantages of MAHR for the biohythane production under optimal pH conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Study the effect of influent pH on biohythane production using MAHR. </LI> <LI> A suitable H<SUB>2</SUB>/(H<SUB>2</SUB>+CH<SUB>4</SUB>) ratio of 16% in M<SUB>H</SUB> was obtained at a pH of 6.5. </LI> <LI> A low pH promoted the proliferation of acetate and butyrate producers. </LI> <LI> Lowering the pH significantly affected the stability of the microbial structure. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>