AMRE*MD – Ammonium recovery from digestate of biogas plants via Membrane distillation

The aim of the project AMRE * MD is to recover the ammonium nitrogen which is contained in the liquid fraction of the digestate of the biogas production by the novel membrane distillation (MD) process.

The obtained nitrogen can be made available again either as fertilizer in better storable and transportable form or as a base chemical, for example, in the chemical industry.

During the project a membrane distillation process is developed which allows to selectively remove ammonium nitrogen (NH4 +) in the form of ammonia (NH3) – present in the liquid residues (digestate, sludges, sludge liquor, manure). Under retention of salts and organic substances, clean ammonium-enriched water is recovered.

The remaining treated liquid fraction of the digestate, in form of recycled clear water, can be easily used in agriculture or for example to dilute the biomass in the fermentation process.

The membrane distillation as a thermal separation process provides for this purpose, an energy-efficient alternative to other separation processes at a low temperature level, which additionally enables the use of the waste heat of the biogas plant and the integration of other renewable energy sources such as solar thermal.

Efficient removal of ammonium nitrogen from the digestate from biogas plants through the AMRE * MD – system will simplify logistical problems, significantly reducing storage, transportation and disposal costs, reduce environmental damage to water and air and generate additional revenues.

Project management:
DI Judith Buchmaier