Kinetics for the Methanogen’s Death in the Acidic Environments
Bibliographic record
Abstract
This study focuses on the inactivation of methanogens under acidic environment that may arise due to overloading of anaerobic reactors. Two types of methanogen-enriched cultures were prepared in the lab-scale reactors using acetate and formate as substrate. Each culture was subsequently incubated in a batch reactor for 6 days under different pH conditions with one of the VFAs of formate, acetate, propionate, butyrate, valerate or phosphate buffer solution. Propidium-monoazide quantitative polymerase chain reaction (PMA-qPCR) analysis and the methane production test revealed that the methanogenic archaea were highly sensitive to the acidic environment. Under the moderate pH of 6.5–7.5, no significant change in cellular decay was observed. However, at pH below 6.5 the decay rate was accelerated leading to archaea’s inactivation. At pH 5.0, the archaeal specific decay rates were elevated as high as 40 times of that at pH 7.0. When the operational pH was the same in the experiments, the cellular decay rate was comparable between the batch test with VFA and that without VFA. These observations strongly suggest that the methanogen decay is caused by low pH rather than the elevated concentrations of VFA compounds (15–40 mM of undissociated VFA) during acidic failure of anaerobic digester.
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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 | 0.001 |
| 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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
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".