Returgant Direkt – Biomass recirculation filter for optimum gas yield

The Returgant Direkt biomass recirculation filter acts as an intelligent filter for biogas plants by controlled recirculation of unfermented fibres back into the fermenter or post-fermenter. This ensures greater biological stability and the complete utilisation of the fed substrates in the biogas plant. As a result, efficiency and gas yield are measurably increased.

The substrate (digestate) is separated into two phases by the Returgant Direkt biomass recirculation filter: this produces a solid substrate (solid phase containing fibres) and a liquid substrate (liquid phase).

The Returgant Direkt biomass recirculation filter extracts substrate from the fermenter or post-fermenter so that, after filtration, it can be specifically recirculated as a thick phase containing fibre material that has not yet been fully digested. This stimulates the overall biological activity in the biogas plant’s fermenter. In this way, the material that has not yet been fully digested (fibres >0.5 mm) is returned to the digester/post-fermenter, where it has time to continue fermenting, thereby increasing the gas yield – as different feedstocks for biogas plants require varying lengths of time for fermentation.

Removing the fibres (fibres < 0.5 mm) makes the fermentation product more liquid, which facilitates its disposal and reduces the need for agitation in the biogas plant’s digestate storage tank.