Optimization of hydrogen dispersion in thermophilic up-flow reactors for ex situ biogas upgrading.
This study evaluates the efficiency of four novel up-flow reactors for ex situ biogas upgrading converting externally provided CO2and H2to CH4, via hydrogenotrophic methanogenesis. The gases were injected through stainless steel diffusers combined with alumina ceramic sponge or through alumina ceramic membranes. Pore size, input gas loading and gas recirculation flow rate were modulated to optimize gas-liquid mass transfer, and thus methanation efficiency. Results showed that larger pore size diffusion devices achieved the best kinetics and output-gas quality converting all the injected H2and CO2, up to 3.6L/LREACTOR·d H2loading rate. Specifically, reactors' CH4content increased from 23 to 96% and the CH4yield reached 0.25LCH4/LH2. High throughput 16S rRNA gene sequencing revealed predominance of bacteria belonging to Anaerobaculum genus and to uncultured order MBA08. Additionally, the massive increase of hydrogenotrophic methanogens, such as Methanothermobacter thermautotrophicus, and syntrophic bacteria demonstrates the selection-effect of H2on community composition.
Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark.
Ilaria
I
Bassani
Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark. Electronic address: panak@env.dtu.dk.
Panagiotis G
PG
Kougias
Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark; Department of Agronomy, Food, Natural Resources, Animals and Environment (DAFNAE), University of Padua, viale dell'Università 16, 35020 Legnaro (PD), Italy.
Laura
L
Treu
Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark.
Hugo
H
Porté
Department of Biology, University of Padua, Via U. Bassi 58/b, 35121 Padova, Italy.
Stefano
S
Campanaro
Department of Environmental Engineering, Technical University of Denmark, Kgs. Lyngby DK-2800, Denmark.
Irini
I
Angelidaki
D056804:Biofuels / Q000382:microbiology*; D019149:Bioreactors / Q000382:microbiology; D006859:Hydrogen; D008697:Methane; D012336:RNA, Ribosomal, 16S / Q000235:genetics
D056804:Biofuels; D012336:RNA, Ribosomal, 16S; D006859:Hydrogen; D008697:Methane
16S rRNA gene sequencing; Ceramic membrane; Ceramic sponge; Ex situ biogas upgrading; Gas-liquid mass transfer rate