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Microbial fuel cell (MFC) technology is receiving a lot of attention recently as a promising technology for generating electricity by treating organic waste resources. Over the past 20 years, the MFC technology has made rapid progress: various research on system architectures, electrochemistry, materials, and microbiology has been conducted for developing practical ideas and fundamental principles. Recently, a lot of research on scaled-up systems for practical application is being conducted in the MFC field. In this review, materials, electrochemistry, system development and scale-up systems of MFCs studied so far are reviewed, and future prospects and directions of MFC technology are presented.

Microbial fuel cell (MFC) is an innovative environmental and energy system that converts organic wastewater into electrical energy. For practical implementation of MFC as a wastewater treatment process, a number of limitations need to be overcome. Improving cathodic performance is one of major challenges, and introduction of a current collector can be an easy and practical solution. In this study, three types of current collectors made of stainless steel (SS) were tested in a single-chamber cubic MFC. The three current collectors had different contact areas to the cathode (P 1.0 cm 2 ; PC 4.3 cm 2 ; PM 6.5 cm 2) and increasing the contacting area enhanced the power and current generations and coulombic and energy recoveries by mainly decreasing cathodic charge transfer impedance. Application of the SS mesh to the cathode (PM) improved maximum power density, optimum current density and maximum current density by 8.8%, 3.6% and 6.7%, respectively, comparing with P of no SS mesh. The SS mesh decreased cathodic polarization resistance by up to 16%, and cathodic charge transfer impedance by up to 39%, possibly because the SS mesh enhanced electron transport and oxygen reduction reaction. However, application of the SS mesh had little effect on ohmic impedance.

A sediment microbial fuel cell (SMFC) is a system in which MFC is applied to a sediment layer of an aqueous system for water purification. SMFCs can remove contaminants from sediments and decompose organic matter while simultaneously producing electrical energy. SMFC is installed in the form of installing an anode in the sediment at the bottom of the water system and a cathode in the water layer above the sediment, and connecting the two electrodes through an external circuit. Early SMFCs were developed to be used as power sources in hard-to-reach deep water areas or remote areas. However, recently, it has attracted a lot of attention as a technology for biologically purifying pollutants through its own power supply. Furthermore, it is being developed as a means of monitoring the environmental condition of the installed area. Despite the importance of SMFC, no comprehensive review has yet been published to the Korean readers on the trends and prospects of SMFC research. Therefore, in this review paper, the mechanism of SMFC, their mechanism of removal of organic, inorganic, and heavy metals, and the current state of SMFC technology are discussed, and future prospects are presented.