Exploring the Determination of Struvite Solubility Product from Analytical Results
Bibliographic record
Abstract
The solubility of magnesium ammonium phosphate hexahydrate (struvite) was determined in different water and wastewater solutions, by using the analytical results of the solubility tests conducted in the Environmental Engineering Lab at the University of British Columbia. The various factors affecting the struvite solubility such as pH, ionic strength and the temperature of the solutions were also studied in this project. The struvite solubility product values were found to vary significantly from one solution to another and over the range of the experimental conditions as well. For instance, the solubility product (Ksp) determined at 20 degrees C for anaerobic digester supernatant from the Penticton, B.C. Advanced Wastewater Treatment Plant, was found to vary from 8.46 x 10(-15) (pKsp =14.07) to 1.3 x 10(-13) (pKsp =12.89), over a pH range 6.45 to 8.97; while in the case of distilled water, with the same struvite crystals and at the identical temperature, it was found to vary from 5.21 x 10(-15) (pKsp=14.28) to 2.12 x 10(-13) (pKsp =12.67) over a pH range of 7.01 to 9.62. These results explore the possible reasons for widely varying struvite solubility reported in the literature. A possible correlation was also developed to correlate struvite solubility product with varying temperature. Furthermore, an attempt was made to establish a correlation between conductivity and calculated ionic strength of the solutions. A significant gap, between the values predicted by the correlation developed in this study and those predicted by the existing correlation, was also observed.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".