Performances et limites d’un procédé à lit fluidisé associant biofilm et liqueur mixte (IFAS) pour le traitement du carbone et de l’azote des eaux résiduaires urbaines
Résumé
Thanks to its compactness and to its capacity to treat both organic matter and nitrogen at an affordable cost, the IFAS process represents an attractive solution to improve retrofitting-activated sludge plants performance. The main objective of this work is to optimize IFAS process with regards to enhance key operation parameters such as F/M ratio by experimental approaches. A 2.8 m3 pilot IFAS fed with raw wastewater was operated at the experimental hall of “La Feyssine” wastewater treatment plant, Villeurbanne, for a period of 2.5 years. The IFAS process was separated in 3 tanks to treat organic matter and total nitrogen separately (anoxic/aerobic, suspended/aerobic IFAS). A F/M ratio between 0.25 to 0.30 kgBOD5/kgVSS/d promote high degree of treatment capacity with acceptable removal rate (nitrogen and carbon). The sludge retention time in mixed liquor is about 4 to 5 days and the ammonium concentration in effluent reach 7 mgN/L at 16°C. To increase denitrification performance and bring more nitrogen substrate to IFAS tank, the first aerobic reactor was aerated a part of a journey (sequence). This configuration showed nitrogen removal up to 80% with 17 hO2/d and improve denitrification process.