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Aqualogic® control system

Springe, Germany

Sewage treatment plant in Springe (33,000 p.e.) Aqualogic® controller system - increasing process stability


Anaerobically stabilised wastewater treatment plants in particular require stable and dynamic control in order to ensure good effluent values on the one hand and a high energy yield from the digestion process on the other.  The Aqualogic┬« control system offers the possibility - based on several measured values - to control, among other things, the aeration of the aeration tank. Based on fuzzy logic, the aeration intensity is continuously adjusted depending on the oxygen and ammonium measurement. The requirement can become critical if industrial dischargers discharge unusual wastewater that is not beneficial to the activated sludge and thus impairs nitrogen elimination. The biological treatment stage at the Springe wastewater treatment plant consists of a recirculation tank that is aerated by means of Passavant┬« Mammutrotoren┬«. Since summer 2018, an upstream denitrification basin has also been in operation.


  • Optimised control of the aeration system
  • Ensuring stable processes and reliable compliance with effluent values
  • Optimisation of P elimination through adapted precipitant dosage
  • Protection against hydraulic overload of the treatment plant (e.g. due to heavy rainfall)


With the Aqualogic® control system, the aeration duration and intensity is dynamically adapted to the consumption. Disturbing processes caused by industrial discharges are automatically recorded. At the same time, the Enerlogic® module was put into operation. This module adjusts the oxygen setpoint depending on the load and regulates the output of the mammoth rotors accordingly. In order to prevent hydraulic overload, the return sludge volume flow is reliably controlled depending on the inflow volume flow of the wastewater treatment plant.
The existing P-analyser is used to continuously and automatically adjust the required precipitant quantity.


By controlling the surface aerators according to demand, the process stability in the wastewater treatment plant has improved significantly. This results in improved and less fluctuating effluent values for nitrogen compounds. In addition, an average saving of 5% in the overall electricity consumption of the treatment plant was achieved, even though additional agitators and pumps were put into operation. By integrating P precipitation into the control system, the P effluent value could be kept stable. However, the amount of precipitant used has been reduced by > 40%.

Technical Data

Passavant® Aqualogic® with Enerlogic®
(energy efficient control) and NH4 / NO3 controller

Module return sludge control
Precipitant dosing module
Recirculation module (retrofitted 2018)


  • Efficient and reliable control of the processes for the biology in a system based on fuzzy logic.
  • Optimisation of the biological purification process with a more stable operating mode
  • Reliable compliance with the prescribed effluent values
  • Detailed setting options directly on the Aqualogic┬« controller
  • Aqualogic┬« is independent of the manufacturer of the PLC, as well as the measuring and aeration technology
  • Possibility of a test phase of several months for the Aqualogic┬« controller system

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