Biodegradation of oestrogens in nitrifying activated sludge
Bibliographic record
Abstract
The degradation of 17beta-oestradiol (E2) and 17alpha-ethinyloestradiol (EE2) was investigated in an aerobic activated sludge system fed with synthetic wastewater. The effect of different solid residence times (SRTs) and nitrification inhibitors, such as allylthiourea (ATU), was studied in order to assess which group of microorganisms plays a significant role in the degradation of oestrogens. E2 was effectively converted into oestrone (E1) under all the conditions encountered in the nitrifying activated sludge system. The degradation of E2 obeyed first-order reaction kinetics; with an increase in SRT from 12 to 20 days, the degradation rate constant, k, decreased from 2.3 h(-1) to 0.47 h(-1). The removal of EE2 did not change significantly with the addition of ATU and at different SRTs. Only about 20% of EE2 was removed from the system, which demonstrated that EE2 was more recalcitrant than natural oestrogens. The results are supported by other recent studies, which suggest that co-metabolic degradation of EE2 and E2 by ammonia-oxidizing bacteria is not an important removal mechanism. The primary mechanism for E2 and EE2 degradation in activated sludge is most probably the activity of heterotrophic bacteria.
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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 | 0.000 | 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 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".