Biofouling of an Aerated Membrane Reactor: Four Distinct Microbial Communities
Bibliographic record
Abstract
Membrane fouling is a significant operational challenge in the application of membranes in drinking and wastewater treatment. Microbial association with the surfaces of membranes and the extracellular polymeric substances (EPS) associated with biofilms contribute to fouling. Within the microbial community, there are polysaccharide producers and consumers. A better understanding of the microbial community at the interfaces of the membrane material will be important in supporting next-generation cleaning strategies. A laboratory-scale mesophilic-aerated membrane bioreactor using sheet polyvinylidene fluoride microfiltration membrane was used as a model system. The microbial community was characterized from four distinct compartments: mixed liquor suspended biomass (MLSB); the membrane cake (i.e., extramembrane loosely bound [EMLB]); the foulant layer (i.e., extramembrane tightly bound [EMTB]), and the intracore membrane biofilm (ICMB). Electron microscope images revealed an established biofilm in the ICMB. Microbial structures were observed in the macrovoids of the asymmetric membrane and the open architecture of the support web. This is the first study to acknowledge the presence of ICMB. The community structure of all four compartments (i.e., MLSB, EMLB, EMTB, and ICMB) was characterized at the genus level and results indicate four distinct microbial communities exist. Composition of the ICMB compartment most closely aligns with MLSB and is distinct from the community found in the contiguous EMTB compartment. Results identify the need to characterize the microbial community, and conditions for growth and EPS production, in both the EMTB and ICMB compartments to understand irreversible fouling. Biofilm characterization in the EMLB compartment is insufficient.
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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) | 0.001 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 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 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".