Complete mixing of the fermentable organic suspension in the fermenter is a requirement for:
- Maximum decomposition of the organic substrates and thus maximum biogas production
- Maintaining constant conditions with regard to temperature and chemical properties in the fermenter
- the avoidance of floating sludge layers
- the avoidance of sedimentation of sand and organic solids
In the BTA® Process, complete mixing in the fermenter is ensured by injecting compressed biogas. After condensate separation, the resulting biogas is compressed to the required pressure by means of rotary compressors and injected into the suspension at the bottom of the fermenter via gas lances, so that a flow roller forms which rises in the centre of the fermenter, moves outwards along the liquid surface and descends again at the tank shell.
Another advantage of gas recirculation is the absence of mechanically moving parts in the closed container and thus far less susceptibility to faults.