Fig. 3

Progress of the biogas production and composition over time for the four reactors. Biogas production for the four reactors (in NL) (a); CH₄ yield for the four reactors (in NL g VS⁻¹) (b); biogas quality (CH₄ and CO₂ in %, H₂S and H₂ in ppm) for CR, R1; R2 and R3 (c, d, e and f, respectively); CR is the cautiously fed reactor; R1, R2 and R3 are the reactors exposed to increasing organic loading rate; P1–P5 are the sampling periods chosen for microbial community analyses; gaps in the curves indicate missing data due to measurement failure