Microbial Electrosynthesis for Harnessing Value-Added Product via Carbon Dioxide Sequestering

Abstract

The increasing levels of carbon dioxide due to the burning of fossil fuels and industrial emissions are a threat to the ecosystem and hence an efficient technique is required to fix this damage. Recently, bioelectrochemical systems (BES) emerged to decrease CO2 emissions and produce biofuel as a renewable source of energy. The microbial electrosynthesis (MES) is a new introduction to BES which uses microorganisms as a catalyst for utilizing CO2 as their electron donor and reduce it to produce gaseous fuels like methane or liquid fuels like acetate, butyrate, ethanol, etc. The various compounds are produced depending majorly on the microorganism used, their metabolic pathway, and the magnitude of the applied external voltage. Microbial electrosynthesis process takes place in the biocathode by reducing CO2 with electrons and protons generated during water oxidation at the abiotic anode. In the e of a biotic anode, oxidation could be performed at the anode chamber via electroactive bacteria (EAB) to convert biodegradable wastes to electrons and protons. The protons percolate through the ion exchange separators while an electron from anode reaches to cathode surface via external resistance to reduce the CO2. The electron mediators were used in es to improve the kinetics of bioelectrochemical reduction of CO2. The present chapter explains the principles of MES; it include the advantages of MES, biochemistry of electron transfer processes in biotic electrodes and microbes involved in cathode for reduction of CO2. Further, this chapter discusses the recent developments in MES, illustrates the biochemical pathway involved in producing the different end products in the cathode chamber and possible downstream processes involved in the recovery of biofuel production. This chapter highlights major physicochemical parameters affecting microbial electrosynthesis processes and challenges. The chapter helps the reader to gain basic knowledge on MES, which has the potential to become the upcoming transformative, feasible and alternate technology to reduce the repercussions of excessive carbon dioxide in the atmosphere and save energy as well.