Advances in Chemical Oxidation of Total Reduced Sulfur from Kraft Mills Atmospheric Effluents
Bibliographic record
Abstract
Chemical oxidation techniques in use for the reduction of malodorous total reduced sulfur (TRS) emissions in the kraft mills atmospheric effluents were reviewed with an emphasis on recent industrial improvements in chlorine dioxide (ClO2) oxidation of TRS as well as on laboratory developments of an iron-based chemistry process. The ClO2 approach was implemented successfully at the industrial scale in two Québec kraft mills. The approach consisted in mixing the non-condensable gases (NCG) containing the TRS with gaseous chlorine dioxide obtained either as a residue from a bleach plant vent stream or through vaporization of fresh solution. Full-scale tests have shown that the amount of chlorine dioxide injected or mixed in the NCG was sufficient to reduce the TRS load below the 10 ppmv-regulated levels in a cost efficient way as compared with incineration. A prospective approach validated in laboratory conditions and using the iron redox chemistry for alkaline oxidative scrubbing of TRS is being investigated at Laval University to reduce the odor pollution and to convert TRS into valuable sulfur. Two configurations were evaluated, one consisting of homogeneous Fe(III) sequestered in trans-1,2-diaminocyclohexanetetraacetic acid (cdta) chelates and another of heterogeneous Fe(III) as Fe/Ce oxides-hydroxides mixtures. The relative performances, advantages and weaknesses of the various chemical oxidation processes were discussed. In addition, the fundamentals of the alkaline oxidative scrubbing of TRS using the iron-based alkaline approach were summarized in terms of the gas-liquid thermodynamic equilibria and of the homogeneous and heterogeneous iron redox reactions.
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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 | 0.001 |
| 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".