Phosphorus Release from Calcium-Based Modified Sludge-Derived Biochar under Low-Molecular-Weight Organic Acids: Dual Role of Inorganic Anions
Bibliographic record
Abstract
Calcium-based substances carrying different inorganic anions will lead to the generation of different phosphorus (P) compounds in sludge pyrolysis products (biochar), which will inevitably affect P release efficiency. The effects of CaO and CaCl 2 (2.5%–20%) on P conversion during pyrolysis at 700 °C were studied. Simultaneously, the influence of three representative low-molecular-weight organic acids (LMWOAs: acetic acid (AA), oxalic acid (OA), and citric acid (CA)) on P release behavior was investigated. The results showed that when the addition amount of CaO and CaCl 2 was 10%, the AP concentration reached the maximum values of 47.05 and 46.98 mg/g, respectively. The main Ca–P of CaO-modified biochar was Ca 5 (PO 4 ) 3 OH, while CaCl 2 -modified biochar was mainly Ca–P (Ca 5 (PO 4 ) 3 Cl and Ca 2 PO 4 Cl) containing Cl. The P release rate of CaCl 2 -modified biochar in LMWOA was faster than that of CaO-modified biochar. Additionally, the order of P release efficiency in biochar is: CA > OA > AA at low concentrations (0.5 and 1.0 mM), OA > CA > AA at high concentrations (2.0 and 5.0 mM). The environmental factors affecting P release were ranked by significance: pH > organic matter concentration > temperature. Heavy metals showed minimal mobility during P release, confirming biochar’s stabilization capacity. Moreover, CaO-modified biochar has good stability and a slow P rate, while CaCl 2 -modified biochar could quickly address P deficiency and may be suitable for a severe P deficiency environment.
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| 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 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".