Pilot-scale operation of thermophilic aerobic digestion for volatile fatty acid production and distribution
Bibliographic record
Abstract
Thermophilic aerobic sludge digestion is operated at elevated temperatures, to achieve sludge stabilization, volatile solids (VS) destruction, and pasteurization. The thermophilic aerobic digestion (TAD) of sludge, under a "microaerated" condition, whereby the system oxygen demand exceeds the supply, has been found to accumulate high concentrations of volatile fatty acids (VFAs), namely acetate and propionate. This VFA-rich TAD supernatant is a potential carbon alternative for phosphorus and nitrogen removal enhancement in biological nutrient removal (BNR) processes. This pilot-scale continuous TAD operation was designed to produce VFA-rich supernatant, without sacrificing sludge solids destruction efficiency. A molecular weight cut-off (MWCO) method was used to analyze the carbonaceous and nutrient distributions in the TAD supernatant. Results suggested that real-time aeration control is necessary to control the micro-aeration operation and optimize the VFA production. The oxidation-reduction potential (ORP) did not correlate well to the actual VFA concentration; however, the ORP monitoring did reflect the status of the micro-aeration condition and the existence of VFAs in the system. The average VFA concentration was found to be in proportion to the sludge concentration in the feed. Also, a certain portion of VFAs was found to associate with particulates and colloids in the TAD supernatant. Key words: digested sludge supernatant, molecular weight cut-off, microaerated, thermophilic aerobic digestion, volatile fatty acids, volatile solids destruction, ultrafiltration.
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How this classification was reachedexpand
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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".