Startup of Electromethanogenic Microbial Electrolysis Cells with Two Different Biomass Inocula for Biogas Upgrading

Published on 2018-02-10T00:29:39Z (GMT) by
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).

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Cerrillo, Míriam; Viñas, Marc; Bonmatí, August (2018): Startup of Electromethanogenic Microbial Electrolysis

Cells with Two Different Biomass Inocula for Biogas Upgrading. ACS Publications. Collection.