Flow-Electrode Microbial Electrosynthesis for Increasing Production Rates and Lowering Energy Consumption

The development of microbial electrosynthesis (MES) for renewable electricity-driven bioutilization of CO2 has recently attracted considerable interest due to its ability to synthesize chemicals with the transition towards a circular carbon economy. However, the increase of acetate production and the decrease of energy consumption of MES using an advanced reactor design have received less attention. In this study, the total acetate production rate using novel flow-electrode MES reactors ((16 +/- 1) g center dot m-2 center dot d-1) was double that using reactors without powder activated carbon (PAC) amendment ((8 +/- 3) g center dot m-2 center dot d-1). The flow-electrode MES reactors had a Coulombic efficiency of 43.5% +/- 3.1%, an energy consumption of (0.020 +/- 0.005) kW center dot h center dot g-1, and an energy efficiency of 18.7% +/- 1.3% during acetate production. The flow-electrode with PAC amendment could decrease the net water flux and charge transfer resistance, while had little impact on the cell voltage, rheological behavior, and acetate adsorption. In the flowelectrode MES reactors, the expression of genes involving in energy production and conversion were increased, and the increase of acetate production was found correlated with the increased abundance of Acetobacterium. The Wood-Ljungdahl pathway (WLP) and reductive citric acid cycle (rTCA) were found to be the pathways responsible for carbon fixation. The concentrations of acetate in the stacked flowelectrode MES reached 7.0 g center dot L-1. This study presents a new approach for the construction of scalable MES reactors with high-performance chemical generation and CO2 utilization.(c) 2021 THE AUTHORS. Published by Elsevier LTD on behalf of Chinese Academy of Engineering and Higher Education Press Limited Company. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).