KoalAplan – Biorefinery Büsnau: Municipal wastewater as a source of ammonium nitrogen, hydrogen and bioplastics

Project goal

A decisive goal of the project is that the utilisation of the particulate organic carbon of the municipal wastewater does not only consist of the production of the comparatively cheap and climate-relevant gas methane, as has been the case so far, but that more sustainable products are created. 

Solution approach

In parallel, the largely particle-free wastewater is purified in the main stream. Ammonium is recovered here, which can be used as nitrogen fertiliser for agriculture. Most of the particulate organic carbon is recovered by sedimentation in the primary settling stage. More than 50 per cent of the total organic carbon in municipal wastewater is bound in solids and is not present in solution. The particles still present in the primary treatment effluent are separated from the municipal wastewater with the help of a microscreen.

Hydrolysate can be obtained from the particulate organic carbon by biochemical splitting with water. The hydrolysate is rich in organic acids and is bioelectrochemically converted to hydrogen and CO₂ in a novel reactor system.

In a further step, the material flows produced in the previous processes (hydrolysate) are converted into polyhydroxyalkanoates (PHA). Polyhydroxyalkanoate can be used to produce biobased plastics.