A SOLUBILITY AND THERMODYNAMIC STUDY OF STRUVITE
Bibliographic record
Abstract
Accumulation of magnesium ammonium phosphate hexahydrate (struvite) on surfaces in contact with wastewater, especially in anaerobic sludge digestion and post-digestion processes, is a widely reported problem in the wastewater treatment industry. The solubility and thermodynamic properties of struvite at different temperatures was studied. Struvite thermodynamic solubility products at temperatures between 10 and 60 'C were determined by variation of solution ionic strength and extrapolation to zero ionic strength, using an appropriate activity coefficient model. The pKsp value of struvite at 25 degrees C was found to be 13.36 (+/-0.07). The pKsp value for a temperature range of 10-60 degrees C varies from 14.36 (+/-0.05) to 14.01 (+/-0.03) with the minimum value of 13.17 (+/-0.05) at 30 degrees C. The effect of ionic strength, pH and temperature on struvite solubility was also studied. The solubility of struvite determined in deionized water was found to be 169.2 (+/-4.3) mg l(-1) at 25 degrees C, with the maximum value of 212.7 (+/-3.8) mg l(-1) at 35 degrees C. Standard enthalpy of reaction, delta Hr degrees calculated from the average Ksp values for the temperature range of 10-30 degrees C, was 23.62 Kcal mol(-1). An analytical expression for the Ksp as a function of temperature has been developed by fitting experimental data.
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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 | 0.000 | 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) | 0.001 | 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 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".