Abstract
A bioanode was optimized to generate current densities reaching 38.4 ± 4.9 A m-2, which brings bioelectrochemical systems closer to commercial consideration. Glucose and lactate were fed together in a continuous or fed-batch mode. The current density increased from 2.3 A m-2 to 38.4 A m-2 over a 33 day period and remained stable thereafter. The coulombic efficiency ranged from 50% to 80%. A change in substrate concentration from 200 mg L-1 to 5 mg L-1 decreased maximum current density from 38.4 A m-2 to 12.3 A m-2. The anode consortia included Firmicutes (55.0%), Proteobacteria (41.8%) and Bacteroidetes (2.1%) constituting two potential electrogenic genera: Geobacter (6.8%) and Aeromonas (31.9%). The current production was found to be limited by kinetics during the growth period (33 days), and mass transfer, thereafter. The results indicate the necessity of removing spent biomass for efficient long term operation and treatment of wastewater streams.