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Vapothermal and hydrothermal pretreatment to enhance the anaerobic digestibility of recalcitrant substrates
Citation Link: https://doi.org/10.15480/882.16488
Publikationstyp
Conference Presentation
Date Issued
2025-06-12
Sprache
English
TORE-DOI
Citation
33rd Europan Biomass Conference & Exhibition, EUBCE 2025
Contribution to Conference
Publisher
Technische Universität Hamburg
Peer Reviewed
false
The natural recalcitrance of lignocellulosic residues necessitates a pretreatment in order to use them as biogas substrates. Accordingly, the effect of vapothermal and hydrothermal pretreatment on biogas and methane yield of solid lignocellulosic biomass residues, i.e., common reed, was assessed. The investigation was supported by a comprehensive compositional and structural analysis. The evaluation was facilitated by taking into account the mass loss caused by the treatment as well as an estimation of the energy consumption of the respective method.
Preliminary tests revealed that the initial water content of the biomass significantly influences the biogas yield when applying vapothermal pretreatment, with a maximum yield achieved at 32-46 wt %FM. The results indicate that residence time has a limited effect, where longer residence times were only and to a limited extend beneficial for hydrothermal pretreatment. However, pretreatment temperature strongly influences methane and biogas yields as well as degradation kinetics. This effect can be related to compositional and structural changes, like a retention of cellulose within the solid biomass as well as reduced crystallinity. Vapothermal pretreatment showed optimal results within a narrow temperature range for the investigated biomass, whereas hydrothermal pretreatment yields remained high across a broader range, with both methods reaching peak biomethane production at 170 °C. While the recorded increase in biomethane potential under the given conditions was numerically higher with hydrothermal treatment (263.1 ± 9.0 mLN CH4 gVS-1; increase + 36 %) compared to vapothermal treatment (247.2 ± 9.6 mLN CH4 gVS-1; increase + 28 %), the difference was non-significant. Taking mass loss as a consequence of the pretreatment into account, vapothermal pretreatment led to a relatively high net increase in methane production (i.e., 18 %), compared to a relatively small net increase via hydrothermal pretreatment (i.e., 6 %). This difference was driven by a higher mass loss and thus a higher carbon loss, which diminishes the biomethane yield. The lower carbon loss was accompanied by shorter effective residence times during vapothermal pretreatment and lower energy consumption, caused by the heating of the process medium.
Preliminary tests revealed that the initial water content of the biomass significantly influences the biogas yield when applying vapothermal pretreatment, with a maximum yield achieved at 32-46 wt %FM. The results indicate that residence time has a limited effect, where longer residence times were only and to a limited extend beneficial for hydrothermal pretreatment. However, pretreatment temperature strongly influences methane and biogas yields as well as degradation kinetics. This effect can be related to compositional and structural changes, like a retention of cellulose within the solid biomass as well as reduced crystallinity. Vapothermal pretreatment showed optimal results within a narrow temperature range for the investigated biomass, whereas hydrothermal pretreatment yields remained high across a broader range, with both methods reaching peak biomethane production at 170 °C. While the recorded increase in biomethane potential under the given conditions was numerically higher with hydrothermal treatment (263.1 ± 9.0 mLN CH4 gVS-1; increase + 36 %) compared to vapothermal treatment (247.2 ± 9.6 mLN CH4 gVS-1; increase + 28 %), the difference was non-significant. Taking mass loss as a consequence of the pretreatment into account, vapothermal pretreatment led to a relatively high net increase in methane production (i.e., 18 %), compared to a relatively small net increase via hydrothermal pretreatment (i.e., 6 %). This difference was driven by a higher mass loss and thus a higher carbon loss, which diminishes the biomethane yield. The lower carbon loss was accompanied by shorter effective residence times during vapothermal pretreatment and lower energy consumption, caused by the heating of the process medium.
Subjects
pre-treatment
vapothermal
hydrothermal
biomethane
biorefinery
bioenergy
DDC Class
660: Chemistry; Chemical Engineering
628: Sanitary; Municipal
540: Chemistry
333: Economics of Land and Energy
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EUBCE_Schultz_2.pdf
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1.08 MB
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