Biological stability of multi-component agri-food digestates and post-digestates

The additional biogas yields during post-digestion (50.9-114.9 dm3/kg TS) accounted for 8.5-27.4% of the biogas productivity of the feedstocks and 40-80% of that of the digestates. The efficiency of the loss of organic matter content was 22.5-40.2%. The decrease in the values of AT4, GP21 and VS content made the post-digestates more biologically stable than the digestates (digestates: AT4 = 13.7-67.0 mg O2/g TS, GP21 = 71.5-130.1 dm3/kg TS; post-digestates: AT4 = 6.6-37.4 mg O2/g TS, GP21 = 15.7-79.2 dm3/kg TS). For digestates and post-digestates, AT4 values strongly correlated with GP21 values.