Simulation of wastewater treatment plants

For the simulation of WWTPs, a wide choice of transport/reactor models and activated sludge models is available. Transport/reactor models include, among others, model blocks for the description of activated sludge in tanks with intensive mixing and/or aeration by surface and pressurised aeration systems and primary and secondary clarification tanks. For cascades of tanks and batch reactors, dedicated blocks are available. Independent from these reactor models, the user can choose which activated sludge model is to be applied. Such models define a number of fractions of wastewater pollutants and micro-organisms as well as a number of chemical and biological processes which are considered important for the respective processes. For the description of reduction of organic load (COD) and nitrogen (nitrification, denitrification), the standard models ASM1 (Activated Sludge Model No.1) and ASM3 of the International Water Association (IWA) can be used.

Biochemical transformation models can be freely edited and modified in a user-friendly way using the SIMBA model editor, which is based on the Petersen matrix notation. Standard models (ASM1, ASM3, ADM1, RWQM1) are supplied with SIMBA.

These activated sludge models are implemented as predefined models in SIMBA:

  • ASM1hsg – Standard model of IWA with well-known modifications for improved applicability, parameter set from HSG simulation
  • ASM3m – ASM3 of IWA with parametrisation according to recommendations of HSG researcher´s simulation group
  • ASM3biop – ASM3 of IWA with an extension by EAWAG for biological phosphorous elimination

Users can define their own model blocks based on their own activated sludge models.



Model blocks for primary and secondary clarification

For the modelling of sedimentation processes in the primary and secondary clarifiers, a wide selection of models of differing complexity is available:

  • Simple model for primary clarification according to Otterpohl/Freud with COD elimination as function of residence time
  • Ideal sedimentation tank (ideal solid/liquid separation; no storage)
  • Ideal sedimentation tank with storage (solid/liquid separation user-configurable; simple storage)
  • 3-layer secondary clarifier model with variable sludge layer