In this study we evaluate and demonstrate the occurrence of nine natural and one synthetic steroid
hormone, including estrogens, androgens and progestagens in biogas final digestate byproduct (digestion
liquid) commonly used as an agricultural fertilizer. We investigated two biogas sites that utilize different
anaerobic digestion technologies (mesophilic and thermophilic) from swine manure and other organic
wastes. Individual hormone concentration levels were observed up to 1478 ng g1 dry weight or
22.5 mg kg1 N with estrone and progesterone reaching highest concentration levels. Evaluation of the
potential environmental burden through the application in agriculture was also assessed on the basis of
predicted environmental concentrations. This study indicates that the biogas digestion process does not
completely remove steroid hormones from livestock manure and use of final digestate byproduct on
croplands contributes to the environmental emission of hormones.