Recovery of phosphorus from chemical sludge
Notice bibliographique
Résumé
The shortage of pure phosphate rocks may be a limitation to the availability of food and other resources to man and animals. Understanding how phosphorus (P) can be recycled from chemical sludge to make-up for the shortage in availability of pure phosphate rocks is necessary as the world continues to survive. The inclusion of chemical sludge for nutrient utilization purposes in a well-drained Entisol (dark-grey sandy Gleyed Regosolic sand) was demonstrated in this work by applying dewatered sludge from Headingley Wastewater Treatment Plant, Canada. Growth room experiments were conducted to determine the effect of chemical sludge (alum phosphate sludge) as a P source to soil and this was compared to commercial fertilizer (monoammonium phosphate). Maize and switchgrass were examined for a 45- and 50-day cycle with 3 replications each. Low-P soil pots of 1.455kg were treated with different P application rates of 9.7, 19.4, 29.1 and 38.8 mg P kg-1 dry soil. For switchgrass, over the three growth cycles, sludge treated pots showed that P availability increased as the cropping cycle increased. The rate of P application to each pot showed no significant variations based on biomass generated in all cycles. Improved P availability was observed in sludge amended pots compared to monoammonium phosphate (MAP) treated and control pots. Switchgrass also experienced increase in aluminum uptake in the biomass as the cropping cycle increased. The application rate of 9.7 mg P kg soil-1 was identified as the best rate for switchgrass growth and P recovery in biomass. Low-P soil was also seeded with maize for four cropping cycles with each cycle lasting about 45 days. Soil pots were amended just once at the beginning of the first cycle and results were analyzed for dry matter yield, P uptake, aluminum uptake and phosphorus recovery efficiency at the end of each cycle. Results showed that sludge is as effective as MAP in P utilization for maize growth and P uptake was higher in sludge than in MAP. Biomass generated from switchgrass and maize could be harnessed as feedstock for biofuel, however, proper analysis of all forms of P and N in the sludge is necessary to prevent overdosing. Chemical sludge was also exposed to alkali solubilization where waste activated sludge (WAS) and dewatered sludge (DS) were treated with different strengths of sodium hydroxide (NaOH). Results highlighted the importance of floc content in the sludge as the solubilization is mostly dependent on the floc content. Statistical analysis showed that maximum sludge solubilization for P was achieved within the first 30min. Further alkali addition showed no significant release of P from the sludge however, P in resulting solution must be analyzed for its separation and recovery cost. All results indicate the potential possibility of reuse of chemical sludge to reduce the challenges around the availability of P rock and provides some insight into the usability of P in chemical sludge.
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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 | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,001 |
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 ».