The Simulation of Activated Sludge Tanks

What are the benefits of hydrograv simulations?

  • Reduced costs by saving energy and investment
  • Optimization of biological processes
  • Optimization of agitators (location, number, power input)
  • Optimization of aeration by determination of the parameters SOTR, SSOTR or SOTE (e.g. according to the German design guidline DWA-M 209)

 

Example 1: Calibration and validation of the modelling approaches for activated sludge tanks

  • Measurement of the 3D water velocities by using a high-resolution acoustic velocimeter
  • Calibration and validation of the modelling approaches, e. g. turbulence modelling, bubble size

Figure: Comparison of measured and simulated velocities in aerated and anoxic zones in an activated sludge tank.

Figure: Comparison of measured and simulated degree of improvment of the parameter SSOTR according the German design guideline DWA-M 209.

 

Example 2: Optimization of the aeration by simulating the parameter SSOTR-Werten according to the German design guideline DWA-M 209

  • virtual oxygen input experiments incl. oxygen transfer by simulation

Figure:   Concentration of oxygen on planes in different activated sludge tanks.

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Example 3: Detection of depositions

  • analysis of water velocities close to the bottom

Figure: Velocities close to the bottom in different zones of an aeration tank (left) and deterministic comparison of different variants by analysing areas with velocities lower than a critical velocity (right).

  • analysis of concentrations of activated sludge close to the bottom

Figure: Concentrations of activated sludge close to the bottom normed with the inflow concentration (left) and determinstic analysis of critical areas with regard to depositions (right).

 

Example 4: Determination of hydraulic retention time

  • simulation und analysis of virtual tracers
  • determination of the number of CSTRs (Continuous Stirred Tank Reactors) in series and further statistical parameters

Figure: Exemplare measure for improving the hydraulic retention time to achive a plug flow.