The energy-saving Biobull® fermenter agitator

Constantly high agitating performance

With the agitator shaft installed at an inclined angle and two propellers mounted at different heights, the agitators generate significant hydraulic performance with horizontal and vertical flow components. The substrate can flow in without obstruction because the agitating elements are not covered by any obstructive built-in components.
The design of the propeller shape, the large hub diameter and smooth, tangential transition to the propeller blade prevent material from wrapping itself around the blades.

Lowest self-generated power consumption

The propeller geometry with its three dimensional profile has been optimised in the fluid mechanics laboratory; this and the large propeller diameters combined with low speeds of rotation mean the agitators generate maximum thrust while drawing very little power. As a result, energy and operating costs are significantly lower!


Important wearing parts are mounted externally and are therefore easy to access for maintenance and servicing. For example, there is no need for the container roof (gas accumulator) to be opened regularly in biogas plants. The agitator shaft is sealed by a gas-tight siphon seal with contactless operation.

The drive unit and coupling are freely accessible for maintenance work
Geared motor and coupling of streisal Biobull®

High reliability and service live

The streisal Biobull® has been available on the market for 15 years, and the first models are still in use. This means we can truly validate its long service life!