Natural reusable calcium-rich adsorbent for the removal of phosphorus from water: proof of concept of a circular economy
Bibliographic record
Abstract
A calcium-rich rock (limestone) was used as adsorbent to remove phosphorus from water. Phosphorus could be subsequently desorbed from limestone at pH = 4, and potentially reused as fertilizer following pH neutralization. Sorption of phosphorus onto limestone was not affected by 100 mM KCl or by the nitrogen present in a commercial fertilizer, but it was hindered by 100 mM NaCl, urea and river water. The phosphorus removed was however never below ∼9 mg P/kg rock, and it increased with increasing phosphorus concentrations in water. Phosphorus removal increased with 100 mM CaCl 2 at neutral pH, likely due to its precipitation. Mixing for 30 s enhanced phosphorus sorption. Desorption of phosphorus from limestone following sorption in deionized water was ∼50%, ∼22%, and ∼11% at pH = 4, pH = 7, and pH = 11, respectively. Phosphorus desorption was lower when sorption had occurred in river water than in deionized water or in 100 mM urea.
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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".