Microbial electrochemical technologies: Industrial and environmental biotechnologies based on interactions of microorganisms with electrodes

This chapter is dedicated to microbial electrochemical technologies (METs), a novel conception for industrial and environmental biotechnology allowing the exploitation of low-value biomasses, like wastewater as well as the production of value-added products. Microbial electrochemical technologies are realized in devices termed bioelectrochemical systems (BES). Primary METs are based on the microbially assisted oxidation or reduction of substrates and the microbially facilitated transfer of electrons between the substrate and the electrode, which serves as microbial electron acceptor or donor. In this chapter the fundamentals of the microbial extracellular electron transfer are discussed, including the different electron transfer mechanisms and their thermodynamics (i.e. their energetic efficiency). Subsequently, major BES classes are presented. These include microbial fuel cells (MFCs) for electricity generation, microbial electrolysis cells (MECs) or BES for the production of value added products as well as bioremediation and biosensor applications. As microbial electrochemical technologies face a rapid progress in their development the chapter highlights the principle concepts rather than engineering details.