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

Overview & Synopsis

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.