Mechanisms of Phosphorus Removal in a Pilot-Scale Constructed Wetland/BOF Slag Wastewater Treatment System
Bibliographic record
Abstract
Removal of PO4-P, NH3-N, cBOD5, chemical oxygen demand (COD), Escherichia coli, and total coliforms in a pilot-scale hybrid constructed wetland (CW) wastewater treatment system was evaluated. Wastewater was sequentially passed through a mixing cell, an aerobic treatment cell, a P treatment cell that contained basic oxygen furnace slag (BOFS), and an anaerobic treatment cell. The system operated for 8 months at an average flow rate of 68 L/day. Mean influent concentrations of PO4-P, NH3-N, cBOD5, and COD were 7, 25, 27, and 60 mg/L, respectively, and mean influent levels of E. coli and total coliforms were 104 and 105 CFU 100 mL−1. Effluent from the system had 95–99% lower concentrations of PO4-P, NH3-N, cBOD5, E. coli, and total coliforms, and a 72% lower concentration of COD, compared to influent values. Backscatter scanning electron imaging coupled with energy dispersive X-ray (EDX) spectra and elemental maps, along with Fourier transform infrared (FTIR) spectra, showed that P was present on the outer layer of the spent BOFS material. Occurrence of calcium-carbonate and phosphate minerals also was indicated through FTIR analysis. X-ray absorption near edge structure (XANES) spectra of samples from the treatment system was consistent with the presence of phosphate adsorbed on calcite, hydroxyapatite, and α-tricalcium phosphate. High pH (11.66±0.70) of pore water in the BOFS cell resulted in inactivation of pathogens. The wastewater pH was subsequently neutralized by sparging CO2(g) before being introduced to the final anaerobic cell.
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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) | 0.001 | 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 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".