Effect of pH level and acid type on total ammoniacal nitrogen (TAN) retention and fouling of reverse osmosis membranes processing swine wastewater
Bibliographic record
Abstract
Wastewaters fed to reverse osmosis (RO) membranes sometimes need to be acidified to prevent inorganic fouling and increase total ammoniacal nitrogen (TAN) retention. In this project, the effect of pH level (6.5–7.1) and acid type (HCl vs. H2SO4) on membrane fouling and cleaning as well as permeate flux and quality during the processing of swine wastewater with a spiral-wound RO membrane was investigated. The use of H2SO4 to lower pH produced slightly higher permeate fluxes than HCl and there was no indication of sulfate precipitates on the membrane. Membrane fouling intensity and flux recovery upon cleaning were not affected by pH level or acid type. Lowering swine wastewater pH from 7.1 to 6.5 with HCl reduced TAN concentration in permeate from 142 to 59 mg/L. Using H2SO4 to lower pH to 6.5 further decreased TAN concentration to 39 mg/L. At pH 6.5 with both acid types, the concentration of unionized NH3 in the permeate was below the Canadian guideline of 0.019 mg/L for the release of wastewater to an aquatic environment. The use of H2SO4 would be recommended with swine wastewater, because of lower cost and volumetric input required to lower pH, as well as higher permeate quality and flux.
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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 | 0.007 | 0.001 |
| 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 | 0.001 |
| 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".