Pre-treatment equipment

Agricultural biomass pre-treatment depends on the feedstock

In order for the biogas plant microbial process to work optimally, the feedstock must meet certain criteria:

• For plant-based feedstocks such as grass or spoiled root vegetables, it is typically enough to crush the feedstock to reduce the size of the piece. At its simplest, the solution includes crushing blades integrated into conveyor screws.
• Fermentation process of challenging feedstocks, such as straw, can also be enhanced with enzymes or other chemicals, if necessary.
• Manure often does not require pre-treatment at all, but, for example, separating slurry before the process is reasonable in some cases.
• At the end of the pre-treatment process, the feedstock material is often mixed with recycled liquid, which homogenises the feedstock mass and initiates the fermentation process effectively.

Biowaste requires pre-treatment equipment

When municipal organic waste (biowaste) comes from mixed waste separation, through separate waste collection or from food industry, it almost always contains plastics and other impurities. These impurities can cause challenges in the biogas reactor and lower the fertilizer value of the end digestate, so it is recommended to separate them before the biogas production process.

There are a number of solutions for the pre-treatment of biowaste, and the equipment is typically selected according to the amount of impurities, the type of biogas reactor and the quality requirements of the end digestate. Options include:

• A hammer mill, where hammer-like “blades” rotating around the shaft press the material against the screen. The hammer mill separates organics and plastics effectively.
• Hydromechanical pulper that uses water to separate organic materials from floating and from heavy particles through different types of bar screens and pumping processes. The pulper is a suitable pre-treatment solution for wet fermentation process biogas plants.
• Drum screen which separates pre-crushed waste fractions from each other by rotating movements moving waste pieces forward.