More manure in agricultural biogas plants: reducing rheological and nutrient challenges

The aim of the project is to significantly increase the proportion of manure in the substrate mix of biogas plants in order to reduce GHG emissions from agriculture. There is little time left to increase the proportion of manure fermented in biogas plants from the current 30% to the targeted 70% by 2030. The focus must be on existing biogas plants that reduce the use of NawaRo and increase the use of manure. However, this increased use (the substrate throughput will double while the energy yield remains the same) will further exacerbate the challenges that plant operators are already facing today (process engineering challenges, nutrient management and emissions from digestate storage). Together with the enzyme manufacturer Biopract GmbH, a project approach is being developed that offers research into promising solutions. The 3 main components are: 1) Use of enzymes to optimize manure fermentation. 2) Struvite precipitation and subsequent phase separation of the fermentation products to optimize nutrient management. 3) Reduction of emissions during the storage of solid fermentation residues through controlled composting in bio-digesters.