Enhanced energy recovery from lignin-rich cattle manure: impact of coupling mesophilic anaerobic digestion with hyperthermophilic hydrolysis
Bibliographic record
Abstract
The recalcitrance of lignin in cattle manure significantly limits energy recovery during anaerobic digestion. Mesophilic anaerobic digestion of cattle manure (CM) was investigated in continuously stirred tank reactors (CSTRs). In phase 1, the control mother reactor (MR) was operated at an SRT of 30 d, while in phase 2 the MR was followed by a hyper-thermophilic hydrolysis reactor (HTH) at 75 °C and SRT of 2 d (HTH2), with recirculation back to the MR which operated at an SRT of 22.4 d. The average steady-state biodegradability based on methane yields, in the MR, after recirculation, was 46 % ± 3 % compared to 42 % ± 5 %, without recirculation, primarily due to enhanced lignin removal of 20 % (12 % without recirculation). HTH1 (1d SRT) was tested at 75 °C to investigate the impact of SRT on solubilization of digested cattle manure (DCM). Biomethanation potential tests (BMP) conducted at 37 °C on DCM, HTH1and HTH2 achieved biodegradabilities of 17 %, 19 %, and 26 %, respectively. Specific methanogenic activity tests (SMA) at mesophilic conditions for DCM and HTH2 showed comparable maximum specific methane production rate (MSMPR) of 14.6 and 14.1 mL CH 4 /g VSS.d for DCM and HTH2. However, at 55 °C, the MSMPR for HTH2 was roughly 3 times higher than at 37 °C but comparable for DCM at both temperatures. Firmicutes and Bacteroidota were the main phyla in MR effluent, HTH2 and all SMA tests at different temperatures (37 °C and 55 °C). Methanosarcina was the most abundant methanogen at mesophilic and thermophilic temperatures. The predominant mechanism for the enhancement of methane production by the HTH recirculation was not solubilization but the enhanced biodegradation kinetics of particulate organics, including lignin, cellulose, and hemicellulose.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| 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".