Fig. 2
Reactor performances of the two-stage processes of bioelectrochemical system (BES) → methane fermenter (MF) and non-bioelectrochemical system (NBES) → methane fermenter (MF), and single-stage process of methane fermenter (MF). a Rate of gas production of hydrogen, methane, and carbon dioxide, b productions of soluble metabolic products. c Carbon balance of the system. The organic loading rate (OLR) of the BES, NBES, and single-stage MF was 1103.8 mg-C/L/day, corresponding to a glucose load of 13.9 mMglucose/L/day. The hydraulic retention time (HRT) of all reactors was 4 days