Nitrification Pathways in Membrane Aerated Biofilm Reactors to Treat Municipal Wastewater
Notice bibliographique
Résumé
Recently, nitritation-denitritation has been demonstrated as an effective nitrogen removal alternative by reducing oxygen consumption and carbon supply, lowering CO2 emission, decreasing sludge production, and minimising the volume of reactors as compared to conventional nitrification and denitrification process. In the meantime, membrane aerated biofilm reactor (MABR) process becomes increasingly attractive due to the efficient dissolution of oxygen via molecular diffusion into water, resulting in up to five times more energy efficient than conventional aerators and above 75% of oxygen transfer efficiencies. Further potential benefits could be realized by combining partial nitrification with MABR. However, the relative importance of nitrogen removal pathways in MABR is still not well understood, due to the lack of reliable methods to measure the amount of their oxygen consumptions.Three MABR parallel testing systems equipped with ZeelungTM (SUEZ WTS, Hungry) membrane fibres were continuously operated for 230 days to treat synthetic wastewater. They included five sequential stages: biofilm seeding followed by the effects of substrate loadings in hybrid and non-hybrid operating modes, and C/N ratios in hybrid and non-hybrid operating modes. A mathematical MABR model based on wastewater process simulation software GPS-x® and calibrated with experimental data.To determine oxygen fluxes and mass transfer coefficients, three different methods were carried out. Results showed that gas phase mass balance (GPMB) method can be used to determine the oxygen flux reliably for MABRs used in wastewater treatment. Coupling with the liquid phase mass balance (LPMB) approach, the extent of partial nitrification can be estimated. Pressure decay mass transfer (PDMT) method could be applied to determine both mass transfer coefficient and the biofilm thickness. Hybrid MABRs (HMABRs) and MABRs achieved the COD removal of 91%, 87% and TN removal of 57% and 40%, respectively. Up to 14% and 11% of influent NH4+-N could be oxidized by partial nitrification by HMABRs and MABRs, respectively. Partial nitrification by both HMABRs and MABRs increased with the ammonia loading, and C/N ratio, while HMABRs had significant advantages in nitrogen pollutant removal at high substrate loading rates over MABRs. Further characterization of biofilm and suspended solids in HMABRs using fluorescence in situ hybridization (FISH) coupled with confocal laser scanning microscopy (CLSM) showed that the biovolume fractions of nitrite-reducing bacteria were up to 26% and 5%, respectively. The oxygen half saturation constants for AOB and NOB were 0.14 and 0.82 gO2/m3, respectively, after model calibration using GPS-x®. This indicated that AOB can grow in lower dissolved oxygen concentration than NOB.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,001 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».