In the past two decades, microbial fuel cell (MFC) and microbial electrolysis cell (MEC) as emerging bioelectrochemical methods have been intensively investigated. These two methods utilizing microorganisms as biocatalysts are basically developed for wastewater treatment and generation of electric energy or hydrogen (H2), respectively. An attractive and varied approach to improve the possibility and efficiency of these systems is the MEC integrated with MFCs which usually the MFC acts as the power supply of MEC. These systems are designed to overcome the specific challenges of stand-alone biochemical setups effectively. Some of the remarkable advantages of this MEC-MFC system are more sustainable voltage production, better overall treatment performance, energy-saving potential, and cost-effective wastewater treatment operation. However, these systems are still in the initial stages of development. In this chapter, the sustainable application of MEC-MFC systems, their structural elements, and factors affecting their efficiency are investigated and discussed.
