Optimization of the aerobic granular sludge process for sustainable wastewater treatment



The aerobic granular sludge process is a true innovation in the field of wastewater treatment. Compared to conventional activated sludge systems it allows 75% footprint reduction, 30% energy savings and up to 17% lower costs. These figures arise from the cultivation of dense granules with bacteria that can remove all nutrients in one single reactor and that make secondary settling tanks unnecessary because of their excellent settling properties. The process is being implemented fast on full-scale.


There still is a need for optimization in terms of reactor design and operation. Further research is required to fully understand the process. Three research objectives are distinguished:

  • Process optimization to further improve effluent quality, energy consumption and costs
  • Exploring the application of off-gas analysis for fundamental insight and everyday monitoring and control
  • Investigate and minimize potential greenhouse gas emissions


  • Mathematical modeling of the purifying reactions and transport processes inside aerobic granular sludge systems
  • Full-scale measurement campaigns
  • Measurements on a lab-scale aerobic granular sludge reactor, a set-up that is unique in Flanders

Project Administration

Researcher: Janis Baeten

Financing: Research Fund - Flanders (FWO)

Project duration: 01.08.2015 - 31.07.2020