Factors affecting methane production from “Isatis Tinctoria L.” by anaerobic digestion

This work aims to verify and compare, in several conditions, the specific methane yield (SMY) of Isatis Tinctoria L, a flowering plant widely used for the indigo blue color extraction in the Urbino dukedom (Marche Region) during the Renaissance epoch. The anaerobic digestion tests on the selected substrates were performed in batch mode and at mesophilic conditions. A lab-scale system representing a variant of the Owen serum-bottle technique was employed in these experiments. A digestate sludge from the anaerobic digestion treatment stage of a large WWTP was used as the inoculum. The methane yield has been correlated with the characterization of substrates before and after digestion and with the aging of substrate before digestion process by means of several techniques. The results provided evidence of distinctive characteristic of the final product as a function of the different composition of the substrates used into the digestion process. The samples exhibited a diverse chemical pattern in terms of VS, TS. Additional variations were observed for thermal profiles and FT-IR spectra.