where Bt;biogas (L/kg TS; L/kg VS) was the cumulative biogas yield at digestion time t (days);
B0;biogas (L/kg TS; L/kg VS) was the maximal biogas yield; kbiogas (days−1) was the biogas production rate constant.
The B0;biogas and kbiogas values were obtained by nonlinear regression analysis with Statistica software, version 10.0 (StatSoft). Presented values of B0;biogas and kbiogas are the averages with standard deviations.