Table 1.
Characteristics of unmixed agri-industrial feedstock and inoculum before anaerobic digestion.
Fig 1.
Biogas production curves (L gas kg-1 VS) of digestion setups at 45°C over 58 days.
The substrate-to-inoculum (S/I) ratios were 0/10 [yellow]; 5/5 [grey]; 7/3 [orange]; and 9/1 [blue]. Data are presented as averages with standard error.
Fig 2.
Cumulative methane production (L CH4 kg-1 VS) during the co-digestion of grape marc and cheese whey at 45°C over 58 days.
The substrate-to-inoculum (S/I) ratios were 0/10 [yellow]; 5/5 [grey]; 7/3 [orange]; and 9/1 [blue]. Data are presented as averages with standard error.
Fig 3.
Experimental volumetric methane production rate (VMPR, L CH4 LWork-1 d-1) and the cumulative specific methane production (SMP, L CH4 kg-1 VS) from digestion setups with grape marc and cheese whey as mixed substrate (S) at different substrate-to-inoculum (S/I) ratios over 58 days of SS-AD.
Data are presented as averages with standard error.
Table 2.
Assessment of physicochemical characteristics after 58 days of treatments at 45°C. The mixed feedstocks were grape marc and cheese whey in ratio 3/1, respectively, before and after digestion at variable substrate-to-inoculum (S/I) ratio: 0/10, 5/5, 7/3, and 9/1. Values recorded as mean ± SE (n = 3).
Table 3.
Elemental characteristics (CHNOS) of the substrates and digestate at varying substrate-to-inoculum (S/I) ratio through the course of treatment.
Fig 4.
Simulations of the cumulative methane production, L CH4 kg-1 VS, using the first-order regression model (orange); and the modified Gompertz model (blue).
Table 4.
Parameters and goodness fit obtained with the evaluated models, first-order kinetic and the modified Gompertz, for the waste treatment over 58 days at 45°C.