Characterization of a Spherical Packing Medium for Biological Nitrogen Removal by Microelectrodes
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Bibliographic record
Abstract
A novel packing medium comprised of a spherical net-like shell, plastic stuffing, and a perforated hollow duct for biological reactors was investigated. In this study, we examined a biofilm process that employed the packing medium for combined aerobic carbonaceous substances removal, nitrification, and denitrification. As a result, we were able to obtain the average of nitrification, denitrification, as well as the chemical oxygen demand (COD) removal capacities, which correspond to 0.2 kg N/m3 · day, 0.3 kg N/m3 · day, and 5.56 kg/m3 · day, respectively. Moreover, the spatial concentration distribution of chemical species inside the packing medium was studied, using microelectrodes for dissolved oxygen, NH4+, NO3−, and redox potential. Clear evidence was found that aerobic/anoxic spatial stratification was formed inside the packing medium, and that due to microbial oxygen utilization, the aerobic zone was limited to a surface layer of 12 mm, which had a corresponding decrease in redox potentials from 157.4 mV to −99.5 mV. It was also found that nitrification dominated in the top 4 mm of the surface layer, whereas denitrification occurred in the deeper part of the packing medium. Furthermore, a gap zone only for aerobic heterotrophic oxidation was found to be present between nitrification and denitrification. This implied that a high C/N ratio could contribute to a decrease in the effective size of the packing medium. Based on the measured DO and NH4+ depth profiles under steady-state conditions, the effective diffusion coefficients of DO and NH4+ in the packing medium were calculated to be 0.0172 m2/day and 9.7 × 10−5m2/day, respectively. The turbulent diffusion of oxygen ensured the sufficient oxygen supply not only for aerobic carbon oxidation but for nitrification inside the packing medium as well.
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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 | 0.001 |
| 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 it