초록
<P>The performance and biomass enrichment of the biocathode of a pair of lab-scale two-chambered microbial electrolysis cells (MEC) were assessed for 95 days as a technology for upgrading the biogas produced in anaerobic digesters, converting CO<SUB>2</SUB> into CH<SUB>4</SUB> through the electromethanogenic process. Two different inocula were compared: (i) a mixture of biomass from the anode of a MEC and anaerobic granular sludge (BC1); (ii) biomass enriched in a methanol-fed upflow anaerobic sludge blanket reactor (UASB) (BC2). Quantitative and qualitative microbial community assessment of the enrichment process on the biocathodes was performed by means of high-throughput sequencing of <I>16S rDNA</I>- and <I>16S rRNA</I>-based massive libraries as well as RT-qPCR of <I>16S rRNA</I> and <I>mcrA</I> genes. Although BC2 had a faster increase in current density than BC1, there were no significant differences neither in the average CH<SUB>4</SUB> production (0.23 ± 0.01 and 0.22 ± 0.05 L m<SUP>–3</SUP> day<SUP>–1</SUP> for BC1 and BC2, respectively) nor in the cathodic methane recovery efficiency (65 ± 8% and 79 ± 17%, respectively). Independently from the origin of the inoculum, total and active archaeal microbial community in both biocathodes was dominated by hydrogenotrophic methanogenic archaea, especially belonging to <I>Methanobacteriaceae</I> family (mainly <I>Methanobrevibacter</I> genus) (84–98% of both <I>16S rDNA</I> and <I>16S rRNA</I> relative abundance).</P><P>Microbial electrolysis cells (MEC) with electromethanogenic biocathodes were assessed as a technology for upgrading the biogas produced in anaerobic digesters.</P><P><B>Graphic Abstract</B><BR><IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ascecg/2017/ascecg.2017.5.issue-10/acssuschemeng.7b01636/production/images/medium/sc-2017-01636f_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/sc7b01636'>ACS Electronic Supporting Info</A></P>