Bioelectrochemical synthesis of intermediate chemicals from carbon dioxide: its outlook for production of commodity chemicals

Bioelectrochemical systems (BES) use electrochemically active biofilm on the electrode as biocatalyst for electrical energy recovery and useful products. BES has been extensively investigated for application to recover bioenergy in the from of electricity and biohydrogen from biodegradable organic matter, biosensor, bioremediation and microbial desalination. The biofilm of BES can exchange electron with the electrode which makes different biological application and metabolic capability of attached microorganisms from the conventional biofilm process. The microbial oxidation and reduction can be combined with ion exchange capability by membrane and separator in the processes, therefore it might be able to facilitate production and separation in the same process. Recently, BES has also been designed to Microbial electrosynthesis (MES) which can reduce proton in cathode chamber into hydrogen and higher organic compounds such as volatile fatty acids and alcohol with power boost-up using external power supply. It was reported that the dual energy source in MEC using both electrical energy from bio- oxidation of organics and power supply can increase energy and coulombic efficiency to 80% and 92%, respectively. Furthermore, the BES concept recently has been introduced into biorefinery which synthesize chemicals by using microbial electron transport between electrode and live bacterial cell. In this process, the cathodic reduction is more focused than the anodic oxidation of organic matters. Alkaline and commodity chemicals such as methane, acetate, ethanol and buthanol can be produced by biotic cathodic reduction reaction using controlled poised potential. This report will investigate the recent findings of BES and its future application for useful product and biorefinery.