Orthophosphate and Residence Time Impacts in Chloraminated Model Distribution Systems
Bibliographic record
Abstract
ABSTRACT The combined effects of orthophosphate addition and residence time on chloramine stability, biofilm development, and nitrification potential in drinking water distribution systems (DWDSs) remain unexplored. Most previous studies examined orthophosphate dose under fixed residence time conditions, leaving a gap in understanding how water age modifies these impacts. This study evaluated the effects of orthophosphate and residence time (6/12 days) on monochloramine decay, biofilm growth, and nitrification potential using bench‐scale systems. At the 12‐day residence time, chloramine decay, biofilm growth, and nitrite accumulation were significantly greater, with orthophosphate amplifying these effects. Biofilm metabolic activity initially increased with orthophosphate before converging with the control, while bulk water metabolic activity remained higher. Genetic profiling revealed microbial community shifts under extended residence time and orthophosphate. These findings demonstrate that orthophosphate, when combined with longer residence times, can accelerate microbial activity and nitrification, highlighting the need to manage both factors to safeguard water quality.
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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 | 0.001 | 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".