Short-Term Effects of Low pH on the Microfauna of an Activated Sludge Wastewater Treatment System
Bibliographic record
Abstract
Abstract Optimum pH for biological (e.g., activated sludge) wastewater treatment is stated to lie between pH 6.5 and 8.0; however, the pH of processed effluent from thermomechanical pulp mills is closer to 4.5 and 5.5. Consequently, pH adjustment of effluent is required with associated costs. The ability of the microfaunal community (protozoa and metazoa) of activated sludge to survive at pH levels below 6.5 was evaluated with samples collected from Corner Brook Pulp and Paper Ltd. (Newfoundland, Canada). Effect of pH was examined at “high pH” (4.5, 5.5 and 6.5 control) and “low pH” (2.5, 3.5 and 6.5 control) under “summer” temperatures of 30°C and “winter” temperatures of 15°C, with impacts assessed after 1 h and 24 h exposure. Effect of pH was found to be temperature-dependent: pH levels down to 4.5 appeared to have little impact on microfaunal abundances at 30°C , but a number of microfauna were negatively affected at 15°C. Low pH levels of 2.5 and 3.5 were detrimental to the population densities of most microfauna. Adverse pH effects were more marked with increased exposure in some cases. An acid-neutralizing ability may be inherent in the activated sludge, as treatment pH increased over 24 h.
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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".