The influence of sulphate on the treatment of azo dye‐containing wastewater in an anaerobic‐microaerobic compartmentalized fixed‐bed bioreactor
Bibliographic record
Abstract
Abstract A fixed bed reactor (FBR) comprised of an anaerobic zone (AZ) coupled to a micro‐aerated zone (MAZ) was used for the biological treatment of synthetic textile wastewater. The azo dye in the textile effluent is expected to be reduced to aromatic amines (decolouration) in AZ followed by biological degradation of the aromatic amines due to oxygen exposure in MAZ. We focused on assessing the effect of sulphate, a common component of textile wastewaters, on the degradation of the tetra‐azo dye Direct Black 22 (DB22). The influence of sulphide, a product of sulphate biological reduction, on the removal of aromatic amines, toxic by‐products of DB22 degradation, was also analyzed. The AZ and the MAZ were filled with expanded clay balls and polyurethane foam, respectively. The chemical oxygen demand and sulphate ratio (COD/SO 4 −2 ) in the feed started at 4.8 ± 0.2 and was later changed to 0.8 ± 0.1 by increasing the sulphate content. This change consequently increased DB22 removal efficiency from 38 ± 11% to 72 ± 6% in AZ and from 56 ± 7% to 75 ± 7% at MAZ, but also resulted in high sulphide concentration and reduced redox potential (ORP) at the MAZ inlet. However, the change negatively affected the degradation of aromatic amines in the MAZ. Aromatic amines were removed only at redox potential values higher than −228 mV and biogenic sulphide concentrations lower than 44 mg HS − /L.
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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".