Fig. 3
Cumulative hydrogen (full line, referred to left y-axis) and methane (dashed line; referred to right y-axis) production curves during dark fermentation of both hydrogen-producing C. beijerinckii AM2 and C. tyrobutyricum AM6 bio-augmented (black line) and non-augmented (green line) agriculture waste biomass. The values refer to 5 gr of green waste (as detailed in the Materials and Methods section). The VS for this quite heterogeneous material was between 250 and 500 gr VS/kg, therefore the cumulative hydrogen production is of 0.6–1.2 ml H2/gr VS, while for methane the cumulative value is of 0.18–0.36 ml CH4/gr VS. Significant differences were determined with a Student's t-test, *p < 0.05, #p < 0.01, ##p < 0.001 of bio-augmented versus non-augmented for each timepoint