Fig. 4From: Enhanced methane production from cellulose using a two-stage process involving a bioelectrochemical system and a fixed film reactorPerformances of the two-stage NBES → FFR and BES → FFR processes using HRTs of 2.5 → 4.2 days. a Rates of gas production in terms of CH4, CO2, and H2. b Production of SCFAs and ethanol. c C balances of the two-stage processes. The cellulose loads of the BES and NBES were both 3555.6 mg C/(L day). The residual C in all reactors was calculated based on the SSsBack to article page