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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.

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The synthesized TiO 2 /Fe 2 O 3 nanostructures supported on powder-activated carbon (PAC) and zeolite at different mole ratios of Fe 3+ /TiO 2 were characterized by XRD, XRF, FESEM, EDX, TEM, FTIR, BET, and, PL analyses and their cyanide photodegradation mechanism was thoroughly discussed. The results confirmed not only TiO 2 /Fe 2 O 3 /PAC had higher photocatalytic and adsorption capability but also better structural stability and reusability for cyanide removal than TiO 2 / Fe 2 O 3 /zeolite. The first-order kinetics model indicated that the photodegradation rate using TiO 2 /Fe 2 O 3 /PAC was 1.3 times higher than that of TiO 2 /Fe 2 O 3 /zeolite. The response surface methodology (RSM) assessment showed that pH, irradiation time and initial cyanide concentration using UV/H 2 O 2 /TiO 2 /Fe 2 O 3 /zeolite system had more effects on the degradation, respectively; whereas the effectiveness of UV/H 2 O 2 /TiO 2 /Fe 2 O 3 /PAC process was highly influenced by initial cyanide concentration than the other two parameters. High R 2 and well-fitted residual plots approved the accuracy of the models in predicting the cyanide degradation efficiency using both the photocatalysts.

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