Impact of reactive settler models on simulated WWTP performance

Krist Gernaey, Ulf Jeppsson, Damien J. Batstone, Pernille Ingildsen

Research output: Contribution to journalConference articleResearchpeer-review


Including a reactive settler model in a wastewater treatment plant model allows representation of the biological reactions taking place in the sludge blanket in the settler, something that is neglected in many simulation studies. The idea of including a reactive settler model is investigated for an ASM1 case study. Simulations with a whole plant model including the non-reactive Takacs settler model are used as a reference, and are compared to simulation results considering two reactive settler models. The first is a return sludge model block removing oxygen and a user-defined fraction of nitrate, combined with a non-reactive Takacs settler. The second is a fully reactive ASM1 Takacs settler model. Simulations with the ASM1 reactive settler model predicted a 15.3% and 7.4% improvement of the simulated N removal performance, for constant (steady-state) and dynamic influent conditions respectively. The oxygen/nitrate return sludge model block predicts a 10% improvement of N removal performance under dynamic conditions, and might be the better modelling option for ASM1 plants: it is computationally more efficient and it will not overrate the importance of decay processes in the settler.
Original languageEnglish
JournalWater Science and Technology
Issue number1
Pages (from-to)159-167
Publication statusPublished - 2006
Event6th IWA International Symposium on Systems Analysis and Integrated Assessment - Beijing, China
Duration: 3 Nov 20045 Nov 2004
Conference number: 6


Conference6th IWA International Symposium on Systems Analysis and Integrated Assessment


  • activated sludge
  • ASM1
  • modelling
  • reactive settler
  • sedimentation
  • wastewater

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