This activates the bacteria, so that the biodegradable constituents are removed from the sludge.

The impeller is fixed to the gear unit output shaft, which is extended vertically downward, a certain distance from the gear unit. To prevent the clarified water from becoming contaminated with gear oil, Flender gear units for water and wastewater are designed with an output shaft featuring an oil retaining tube and a non-contacting, non-wearing shaft seal.

The axial and lateral loads resulting from the process are absorbed by extra-heavy-duty output shafts and output bearings.