Integrated acid-thermal and enzymatic hydrolysis of hardwood residues with anaerobic digestion: Effects on carbohydrate and biomethane recovery
Bibliographic record
Abstract
Canada has one of the world’s largest forestry industries, which generates substantial amounts of woody residues. The hardwood residues are often underutilized or disposed of at low value, creating both environmental and management challenges. This study investigates the enhancement of carbohydrate solubilization and biomethane recovery from two Canadian hardwood residues, poplar and maple, using combined acid-thermal pretreatment and enzymatic hydrolysis followed by anaerobic digestion (AD). The integrated pretreatment approach significantly improved carbohydrate solubilization and subsequent methane yields. Maximum carbohydrate recovery after acid-thermal pretreatment reached 73% for poplar and 63% for maple. With the addition of enzymatic hydrolysis at the acid-thermal pretreatment scenario of 170°C, carbohydrate recovery further increased to 80% and 70%, respectively. As a result, biomethane yields increased up to 335 mL CH 4 /g COD_added, with a maximum yield of 313 mL CH 4 /g initial wood. Kinetic analysis revealed that the modified Gompertz model provided the best description of the biomethane production rate. Optimal conditions generally included lower solid/liquid ratios (5 %) and lower acid concentrations (0.5%) at moderate temperatures (170°C), which favored fermentable sugar production. However, higher temperatures (200°C), while enhancing carbohydrate release, reduced subsequent AD performance, likely due to the generation of inhibitory or recalcitrant compounds. These findings demonstrate that combining pretreatment improves hardwood residue carbohydrate recovery and subsequent biomethane production. Additionally, this study provides a sustainable approach to managing abundant forestry waste streams, contributing to renewable energy generation and greenhouse gas reduction in Canada. • Polar consistently outperformed maple in carbohydrate and biomethane yield • High sugar yield linked to mild pretreatment, minimizing inhibitor formation • Maximum CH 4 yield reached 335 mL/g COD under optimal pretreatment conditions • Up to 80% carbohydrate recovery from poplar under optimized pretreatment
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".