Pretreatment and conditioning of municipal wastewater secondary sludge using freezing and a combination of ultrasound and freezing
Notice bibliographique
Résumé
With the cost of sludge management on the rise, the volume reduction of municipal wastewater sludge is becoming an increasingly important issue for wastewater treatment plants. Current research is focused on pretreatment methods intended to increase the efficiency of anaerobic digestion. Unfortunately, many of the pretreatment methods studied show little to no improvements in dewaterability of the secondary sludge. This research was carried out to investigate the potential of freezing and combined ultrasound-??freezing methods for simultaneous sludge pretreatment and conditioning. Three methods of freezing were employed; conventional freeze-??thaw (FT), combined ultrasonic-??freezing (UF) and progressive ultrasonic freezing (PUF). The solubilisation of sludge organic matter, evaluated by measuring soluble chemical oxygen demand (sCOD), showed significant improvements for all freezing methods compared to the controls. The maximum increase in sCOD was 6.5 times the control for conventional freezing at -??30?C and 5 freeze-??thaw cycles, 5.3 times the control for combined ultrasonic freezing at 20% amplitude and 12 minutes of sonication and 7.7 times the control for the liquid portion of the progressive ultrasonic freezing samples with a three second sonication pulse for the duration of the freezing. The dewaterability of the freezing methods was also evaluated by measuring sludge volume index (SVI) and capillary suction time (CST). The three freezing methods showed significant improvements in dewaterability with CST ratios ranging from 0.12 ? 0.21 for conventional freezing, 0.11-?? 0.21 for combined ultrasonic freezing and 0.15 ? 0.26 for the solid portion of the progressive ultrasonic freezing samples. The freezing methods were compared to three commonly studied pretreatment methods (thermal, microwave and ultrasound) and showed equivalent or better abilities to solubilise sludge organic matter and improve dewaterability. Further tests revealed that the three freezing treatments also resulted in significantly higher concentrations of proteins as well as increased biodegradability and gas production. The gas production ratio over the control was greatest for conventional freezing (1.52), followed by combined ultrasonic freezing (1.17) and progressive ultrasonic freezing (1.13). The results suggest that freezing could be a very effective pretreatment method as it would be able to simultaneously improve both anaerobic digestion efficiency as well as dewaterability.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 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 | 0,000 |
| 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 tête enseignante, 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 ».