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Microbial fuel cell (MFC) is a novel technology that can be used for electricity generation during oxidization of the organic substances presented in the substrate. To obtain a desirable performance, it is essential to understand the influential factors on the MFC. Among the numerous factors affecting the MFC performance, substrate, microorganisms and their metabolism, electron transfer mechanism in an anodic chamber, electrodes material and the shape of electrodes, type of membrane, operating conditions such as temperature, pH and salinity, electron acceptor in a cathodic chamber and geometric design of the MFC are considered as the most important factors. Among different substrates, wastewater is a sustainable rich medium which can be treated by MFCs. There are various types of exoelectrogenic bacteria presented in wastewaters which can oxidize organic matter and transfer electrons to the anode without using mediators. Like other microbial systems, optimum pH and temperature enhance the bacterial growth which can improve the MFC performance. Despite the negative effect of salt on microbial growth, higher salinity and ionic strength can increase the conductivity of substrate and therefore enhance MFC performance. Scaling up MFC is a controversial issue which needs a comprehensive understanding of these factors. By using new inexpensive materials for electrodes and membrane for manufacturing MFCs, a more cost-effective design for scalable wastewater treatment and high power generation can be achieved. Furthermore, MFC is a suitable candidate for bioremediation of contaminated groundwater. These factors and their impact on the MFC performance have been reviewed in the present survey.

Bio-electrosynthesis is one of the significant developments in reverse microbial fuel cell technology which is potentially capable of creating organic compounds by combining CO2 with H2O. Accordingly, the main objective in the current study was to present a model of microbial electrosynthesis for producing organic compounds (acetate) based on direct conduction of electrons in biofilms. The proposed model enjoys a high degree of rigor because it can predict variations in the substrate concentration, electrical potential, current density and the thickness of the biofilm. Additionally, coulombic efficiency was investigated as a function of substrate concentration and cathode potential. For a system containing CO2 as the substrate and Sporomusa ovata as the biofilm forming microorganism, an increase in the substrate concentration at a constant potential can lead to a decrease in coulombic efficiency as well as an increase in current density and biofilm thickness. On the other hand, an increase in the surface cathodic voltage at a constant substrate concentration may result in an increase in the coulombic efficiency and a decrease in the current density. The maximum coulombic efficiency was revealed to be 75% at a substrate concentration of 0.025 mmol cm(-3) and 55% at a surface cathodic voltage of -0.3 V producing a high range of acetate production by creating an optimal state in the concentration and potential intervals. Finally, the validity of the model was verified by comparing the obtained results with related experimental findings.