Biogas production from manure effectively reduces GHG emissions in agriculture and supports a circular economy through nutrient recycling, with life-cycle assessment (LCA) studies showing an 80% reduction in emissions compared to conventional manure management practices.

Furthermore, Lima et al. (2025) highlights that appropriate handling and treatment of digestate offer additional opportunities to further mitigate environmental impacts. Digestate separation, which divides slurry into an N-rich liquid fraction and a P-rich solid fraction, allows for more precise nutrient application and facilitates the redistribution of the solid P-rich fraction to P-deficient fields, reducing nutrient loss and water contamination.

The study evaluated six manure management scenarios for environmental assessment. These included a Baseline scenario, representing current practices where slurry digestate is applied locally in the Kalmar region, Sweden, and a Separation scenario, where the phase separated liquid and solid fractions are also applied locally. Additionally, four alternative scenarios explored the transport of the solid fraction to other regions.

The study demonstrates a net reduction of 26.4% in climate impact (GWP) for the Separation scenario compared to Baseline. Additionally, the findings suggest that the separation process can facilitate the transport of the solid fraction over distances of up to approximately 250 km without increasing the environmental burden relative to Baseline scenario. Simultaneously, it enables nutrient redistribution to other catchment areas, helping to mitigate eutrophication in the Baltic Sea.

The separation method evaluated in this study is based on ongoing trials at the More Biogas AB plant, utilising preliminary results on separation efficiencies achieved through screw press and decanter centrifuge treatments. The study also evaluated drying, highlighting that the choice of heating method is crucial for environmental impact and relevance.