Anaerobic wet digestion of the organic fraction of waste
The purified biosuspension is temporarily stored in a suspension tank. It decouples the treatment section from the actual fermentation so that the latter can take place independently of the working rhythms of the waste reception.
The organic suspension is fermented in fully mixed fermenters, usually single-stage and mesophilic fermentation at 35 - 38 °C. The design of the fermenter and its mode of operation depend on the type of feedstock and the project-specific requirements for microbiological degradation and biogas yield. The design of the fermenter and its mode of operation depend on the type of feedstock and the project-specific requirements for microbiological degradation and biogas yield.
Use synergies! Digester circulation with biogas
In practice, stirring fermenters causes major problems in many systems. In the wet-mechanical treatment of the BTA® Process, a practically disturbance-free organic suspension with high homogeneity is ensured. This makes it possible to keep the fermenter reliably homogeneous by injecting biogas. This brings decisive advantages:
- Safe circulation of the entire fermentation room
- Optimal access for the microorganisms
- High utilisation of the energy input
- No moving parts in the fermenter, therefore minimal vulnerability
- No maintenance work required inside the fermenter
Further processing of the digestate
The further treatment of the digestate can be adapted to the specific project. As a rule, solid-liquid separation takes place via solid bowl centrifuges or screw presses. The dewatered digestate (dry matter approx. 30%) is ideally suited for further stabilisation and production of quality compost. Most of the resulting centrate is used as process water and circulated. This keeps the fresh water requirement to a minimum.