The fate of per- and polyfluoroalkyl substances (PFAS) during pyrolysis and co-pyrolysis of biosolids with alum sludge and wheat straw
Why this work is in the frame
A frame that forgets how it found something cannot be audited. These are the routes that admitted this work.
Bibliographic record
Abstract
The literature suggests that the pyrolysis of biosolids merely volatilizes per- and polyfluoroalkyl substances (PFAS) into gas or liquid phase, requiring a thermal oxidizer operating at 900–1200 ºC with more than 2 second residence time, to destroy the volatilized PFAS. This study investigates the potential and extent of destruction of PFAS under pyrolysis environment. Pyrolysis and co-pyrolysis experiments were conducted in a bench-scale horizontal fixed-bed reactor. Co-pyrolysis experiments was carried out by blending biosolids with alum sludge or wheat straw at a 1:1 (w/w) mixing ratio at 600 °C. Gas and solids residence times in the reactor were approximately 10 seconds and 1 hour, respectively. The study also explored the effects of lime and biochar as catalysts on PFAS destruction. Results showed near complete removal of PFAS from biochar with the total PFAS concentration reducing from 409.9 ng/g in biosolids to 0.31 ng/g in biochar, suggesting significant volatilization or decomposition at 600 °C. However, PFAS concentrations in volatile products were also significantly low (5.5 ng/g in bio-oil and 0.15 ng/g in scrubber water), indicating 99.4 % PFAS destruction efficiency. The co-pyrolysis of biosolids further improved PFAS removal, likely due to dilutive and synergistic effects. However, catalysis with lime and biochar did not have a significant effect on the PFAS destruction efficiency. This research highlights the potential for near complete PFAS destruction in pyrolysis and co-pyrolysis under the current experimental conditions but emphasizes the need for further investigations under the operational parameters of large-scale pyrolysis plants. • Biosolids pyrolysis at 600 ℃ achieved > 99 % PFAS destruction under sufficient residence time. • Co-pyrolysis with alum sludge and wheat straw increased PFAS destruction compared to sole pyrolysis. • Residual PFAS concentration in biochar met proposed regulations for unrestricted land applications. • Lime and biochar catalysts had minimal effect on PFAS destruction during biosolids pyrolysis.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.002 |
| 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 it