Case Study Activated Sludge Plant

Retrofit and upgrade of an oxidation ditch 

The oxidation ditch in Germany was retrofitted and upgraded. The old and worn rotors were replaced by FUCHS OXYSTAR Aerators. After refurbishing the plant now basically consists of a fine screen, two oxidation ditches (operated in parallel) and a sedimentation tank. Design capacity is 2,000 p.e.


Type of wastewater:municipal
Cleaning objective:complete BOD/COD removal,
advanced nitrification
Oxidation ditches
  • volume:
  • water depth:
  • bottom width:

approx. 2 x 306 m³
approx. 1.2 m
approx. 1.3 m





2 x FUCHS OXYSTAR Aerator per ditch
(nominal power: 4.0 kW each)





  • The site is affected by large storm water. To cope with the varying water level the FUCHS OXYSTAR Aerators are installed on flotations. Consequently, constant oxygen transfer is achieved.
  • To follow the varying oxygen demand the aerators are operated intermittently. Intermittent operation is controlled by oxygen probes.
  • Additional aerators are not required, as for thorough mixing of the activated sludge mixture one aerator per ditch is sufficient.
  • Since the installation of the FUCHS OXYSTAR Aerators there have not been any problems with spray water and freezing of the wastewater during winter time. Year-round operation of the plant is guaranteed.


Efficient and economical wastewater treatment


Activated Sludge Plants
Oxygen for clear water with FUCHS Aerators