Reception and preparation
Solid fermentation residues with a high dry-matter content are received, optionally blended with other fibre-rich residues and mechanically prepared.
Process solution for digestate
Digestate valorisation for additional biogas and biomethane
Fibre-rich digestate from existing biogas plants can retain usable organic and residual methane potential. The process combines preparation, hydrolysis and post-digestion to recover additional energy while upgrading plant nutrients into fertiliser products.
Technology basis: European patent application EP 4 410 946 A2
Starting challenge
Why fibre-rich digestate can still contain residual methane potential
After the first anaerobic digestion stage, lignocellulosic plant fibres in particular remain. They are difficult for microorganisms to access but still contain organically bound energy and residual methane potential. At the same time, the digestate contains valuable mineral plant nutrients that should be preserved and converted into products suitable for transport and application.
Process principle
From digestate to additional biogas, biomethane and fertiliser products
Aerobic pretreatment
An intensive, time-limited oxygen treatment—through intensive aerobic conditioning and/or within the biosuspension—improves access to the fibre-rich organic components.
Preparation of the biosuspension
Filtrates and condensates from downstream treatment are recycled as process liquid, producing a pumpable biosuspension suitable for wet fermentation.
Multi-stage anaerobic digestion
Hydrolysis and anaerobic methane production take place in separate process vessels. Culture-preserving operation and mesophilic or thermophilic stages support stable biological degradation.
Gas and nutrient utilisation
The produced biogas can be used for energy or upgraded to biomethane. Nutrient streams are processed into organic NPKS fertilisers and, where applicable, liquid fertiliser products.
Client benefits
More value from existing material streams.
Additional energy production
Utilisation of organic matter that remains in the solid digestate after conventional primary fermentation.
Preservation of plant nutrients
Mineral nutrients are not destroyed thermally but concentrated in upgraded organic fertiliser products.
Process-water recycling
Where technically feasible, filtrates and condensates are recycled as suspension and process liquids.
Reduced need for newly cultivated biomass
Additional energy is generated from residues already available and therefore does not create renewed competition for farmland, food or feed.
Suitable material streams
Suitable digestate for post-digestion and methane recovery
Solid digestate from energy-crop biogas plantsFibre-rich plant residues and straw silagesAnimal excreta with a high dry-matter contentFruit pomace, brewery and distillery residues, and starch pulp
Project development
Let us assess together whether this process solution fits your material streams and project objectives.
Note: Detailed technical design and clarification of intellectual-property and usage rights are handled on a project-specific basis.