Operational variables and microbial community dynamics affect granulation stability in continuous flow aerobic granular sludge reactors

Oscar Franchi, María Ignacia Álvarez, Juan Pablo Pavissich, Marisol Belmonte, Alba Pedrouso, Ángeles Val del Río, Anuska Mosquera-Corral, José Luis Campos

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Retrofitting wastewater treatment plants with continuous aerobic granular sludge reactors is a promising alternative to enhance treatment capacities and reduce footprint. This study investigates the main variables influencing granulation and microbial dynamics in two reactor configurations (25 L): stirred tanks in series (R1) and a plug-flow-like system (R2). Granule formation was achieved by increasing the organic loading rate (OLR) from 0.7 to 4.1 kg COD/(m3·d) and the up-flow velocity in the biomass selector from 1.4 to 6.9 m/h. However, irreversible granule destabilization occurred at day 68 for R1 and day 108 for R2. Principal component analysis and examination of food-to-microorganisms (F/M) ratio medians identified the F/M ratio as the primary variable associated with instability. Microbial analysis revealed that a high F/M ratio induced significant increases in the abundance of specific genera such as Arcobacter, Cloacibacterium, Rikenella, Aquaspirillum and Sphaerotillus, whose overgrowth may negatively impact granule stability. Based on these findings, maximum F/M ratio thresholds were obtained to establish operational conditions allowing the maintenance of stable aerobic granules on continuous flow reactor configurations.

Original languageEnglish
Article number104951
JournalJournal of Water Process Engineering
Volume59
DOIs
StatePublished - Mar 2024
Externally publishedYes

Keywords

  • Aerobic granular sludge
  • Continuous flow
  • Food to microorganisms ratio
  • Hydraulic selection pressure
  • Microbial community

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