How does a biogas agitator work?

A biogas agitator ensures uniform homogenisation in a biogas plant. It prevents floating layers and sedimentation, distributes heat and nutrients throughout the substrate and creates stable conditions for biological processes. This makes the agitator a key component for safe and economical plant operation.

Below, you will learn how a biogas agitator works from a technical perspective, which types of agitators are used at Paulmichl and what advantages a properly designed mixing system offers.

How a biogas agitator works – explained step by step

The demands placed on a biogas agitator are high: the substrate is often viscous, rich in fibres and varies depending on the feedstocks used, operating conditions, dry matter content and season. The aim of the mixing technology is therefore not to move the contents of the tank as vigorously as possible, but to circulate them evenly and in a controlled manner. The following steps explain how this is achieved technically.

1.    Drive and power transmission

An electric motor drives a shaft via a gearbox. At the end of the shaft is the mixing element, which is responsible for moving the substrate. The drive is designed for energy-efficient operation in viscous, fibre-rich media.

2.    Generation of a circulation flow

The rotation of the agitator blades sets the substrate in motion. This creates a directed flow that circulates the tank contents throughout the entire vessel. The aim is not aggressive mixing, but uniform, gentle circulation of the entire tank volume.

3.    Breaking up floating layers and sediment

Light components such as fibrous materials are mixed back into the liquid phase from the surface. At the same time, heavy particles are prevented from settling permanently at the bottom. This ensures maximum gas yield from the biogas plant.

4.    Uniform distribution of heat and nutrients

Agitation ensures that temperature, trace elements and fresh substrate are evenly distributed throughout the digester. This creates stable conditions for microorganisms and ensures uniform fermentation.

5.    Stabilisation of gas production

Homogeneous mixing allows the biological processes to operate more consistently. This has a positive effect on process stability, gas yield and plant availability.
 

Types of biogas agitators at Paulmichl

Depending on the digester size, substrate and application, Paulmichl uses different types of biogas agitators:

Advantages of properly designed mixing technology

✓ Uniform mixing of the contents of the biogas tank
 ✓ Prevention of floating layers and sedimentation
 ✓ Stable biological processes and consistent gas production
 ✓ Uniform temperature distribution
 ✓ High plant efficiency with low energy consumption
 

Practical example: Biogas agitators from Paulmichl GmbH

Paulmichl has been developing mixing technology for the biogas and environmental technology sectors for decades. The focus is on robust, durable designs and practical solutions tailored to the specific tank and substrate used.
The potential of customised mixing technology becomes particularly evident when modernising existing plants: if floating crusts, dead zones or uneven temperatures interfere with the process, a properly coordinated agitator system can significantly improve plant stability and economic efficiency.