Trihalomethane formation in drinking water and production within a polyvinyl chloride pipe environment
Bibliographic record
Abstract
This project used pipe-incubated water samples collected from a pilot plant in North Vancouver, B.C., and the material-specific simulated distribution system (MS-SDS) test (Brereton 1998) to investigate the interaction between chlorine residuals in drinking water and the interior surface of polyvinyl chloride (PVC) distribution system pipes. Seasonal differences and residence time were important factors in trihalomethane (THM) production, and surface biofilm had a more significant impact on chloroform formation in bulk water than the treatment process. Biofilm adsorption has been identified as one surface mechanism responsible for the removal of THM precursors from the bulk water phase. This study observed that compounds previously adsorbed and extracellular materials from biofilm bacteria (including protoplasm from lysed cells) could participate in the aqueous chloroform formation in the absence of available precursor. Under chlorination conditions typical to the Greater Vancouver Regional District (GVRD) utilities, additional precursors were masked by the chlorine-limited condition; however, experiments confirmed that the practice of rechlorination would increase THM production beyond its bulk water capacity. Heterotrophic plate counts (HPCs), measured from biofilm scrapings, revealed that higher chloroform production was accompanied by bacterial regrowth. A proposed model summarizes the major mechanisms interacting in a PVC pipe environment. Key words: biofilm, chloroform, distribution system, drinking water, material specific simulated distribution system (MS-SDS), PVC pipe, regrowth, trihalomethane (THM) formation.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 |
| 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".