Sorption and desorption of diverse contaminants of varying polarity in wastewater sludge with and without alum
Bibliographic record
Abstract
Sewage sludge sorption and desorption measurements were conducted for nine diverse contaminants of varying polarity: caffeine, sulfamethoxazole, carbamazepine, atrazine, estradiol, ethinylestradiol, diclofenac, and, for the first time desethylatrazine and norethindrone. Two types of sorption behaviour were observed. Compounds with a log octanol-water partition coefficient, log Kow, below 3 showed little or no sorption over 48 hours of shaking, while compounds with log Kow over 3 showed 30 to 90% sorption within the first few minutes. After 6 hours of shaking, mass loss through suspected biotransformation became evident for some compounds. At the pH range considered (5.7-6.7), diclofenac (pKa 4.0, log Kow 4.5) was the only compound in which pH dependent sorption could be quantified. The log sewage sludge-water distribution coefficients, log Kd, ranged from 0.2 to 2.9, and, as expected, increased with increasing log Kow of the compound and organic carbon (OC) content of the sewage sludge. A sewage sludge precipitated with alum had a substantially lower Kd values, as well as lower OC content, compared to alum-free sludge. Desorption was studied by sequentially replacing supernatant water. With each water replacement, log Kd values tended to either remain similar (following a linear isotherm) or in some cases increase (following a Freundlich-type isotherm). The length of time required to restore equilibrium increased with each rinsing step. A literature review of reported Kd values compared well with the alum-free sludge data, but not the alum-sludge data. Sewage sludge Kd across the literature appear more consistent with increasing Kow.
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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) | 0.000 | 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) | 0.001 | 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".