Fig. 5
Genus-level compositional view of the microorganisms in the fermentation cultures on the cathodic and anodic sides of the bioelectrochemical system (BES), non-bioelectrochemical system (NBES), second-stage methane fermenters (MFs) (← BES and ← NBES), and single-stage MF. Genera of lower similarity (< 97%) and lower abundance (< 1.0%) were included under Uncultured Bacteria and Others, respectively. The numbers 1, 2, and 3 indicate the hydraulic retention time (HRT) and pH of the substrate (pHin) in the first stage for the two-stage process as follows: 1: 4 days and 6.5, 2: 2 days and 6.5, and 3: 2 days and 7.3. The number 4 indicates the HRT (4 days) and pHin (7.7) in the single-stage MF