Monochloramine effects on biofilm growth with/without orthophosphate in high-residence time drinking water model distribution systems
Bibliographic record
Abstract
ABSTRACT Orthophosphate is a common corrosion inhibitor used to control lead release in drinking water distribution systems (DWDSs). It may enhance monochloramine decay and promote biofilm growth. This study assessed the impact of two monochloramine dosages on biofilm growth and monochloramine decay in model distribution systems (MDSs), with/without orthophosphate, at a 10-day residence time. Four bench-scale MDSs were run for 15 weeks: two tested a low monochloramine dose (2 mg Cl2/L), with or without orthophosphate, and two a higher dose (3 mg Cl2/L), with and without orthophosphate. The feedwater was phosphorus-limited, which may have amplified microbial response to orthophosphate addition. At both monochloramine dosages tested, orthophosphate addition increased viable cell count, biofilm reformation potential, and metabolic activity, while biofilm genetic diversity was influenced by both orthophosphate and monochloramine dose. Communities subjected to high monochloramine without orthophosphate were the least diverse, whereas those exposed to low monochloramine with orthophosphate showed the greatest diversity. These findings suggest that high monochloramine exerts selective pressure, reducing diversity, while orthophosphate enhances it. First-order total chlorine decay coefficients were higher in MDSs with lower monochloramine doses, and at the same dose, MDSs with orthophosphate showed slightly higher monochloramine decay than those without orthophosphate.
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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".