The effect of solids retention time on dissolved methane concentration in anaerobic membrane bioreactors
Why this work is in the frame
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Bibliographic record
Abstract
We assessed the effect of solids retention times (SRT) on dissolved methane concentration in a lab-scale anaerobic membrane bioreactor (AnMBR) operated at SRT 20d and 40d at ambient temperature (23 +/- 1 degrees C). Daily methane production was 196 +/- 17 mL/d and 285 +/- 18 mL/d for SRT 20d and 40d, respectively. In comparison, the average concentration of dissolved methane in AnMBR permeates was 9.9 +/- 2.3 mg/L for SRT 20d (close to thermodynamic equilibrium), which was decreased to 4.3 +/- 0.3 mg/L for SRT 40d. We often found oversaturation of dissolved methane at SRT 20d, which means that mass transfer of dissolved methane from liquid to gas phase is dynamic at this short SRT. However, we never detected oversaturation of dissolved methane at SRT 40d, due to slow endogenous decay kinetics. Higher daily methane production at SRT 40d than that at SRT 20d indicates that methane was supplementarily produced from biomass electrons by endogenous decay. This study shows that operation of AnMBRs under long SRT can keep low dissolved methane concentration in AnMBR permeate, along with high methane yield.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.002 |
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 it