The invention relates to a method and a bioreactor for drying biogenic residues to a dry mass comprising filling the residues into a bioreactor filled with spheres and mixing the spheres and the residues so that films of the residues form on the surfaces of the spheres, drying the films of residues with the formation of crusts of dry mass with a residual water content on the surfaces of the spheres by feeding a drying medium into the bioreactor,
grinding and further drying the dry mass by mixing and grinding off powdery dry mass from the spheres.