MECs operated in duplicate. The MEC reactor with the anode acclimated to the synthetic mixed substrate from a pre-acclimated inoculum were then fed with effluent from cellulosic material fermentation: cellobiose (conductivity=8 mS; pH=7.3) or corn stover (conductivity=7 mS; pH=7.2) from 2 different batches provided by the National Renewable Energy Laboratory (NREL).