Treatment of mixed dairy and dye wastewater in anode of microbial fuel cell with simultaneous electricity generation

Microbial fuel cell (MFC) is a green technology that converts the stored chemical energy of organic matter to electricity; therefore, it can be used for wastewater purification and energy production simultaneously. In this study, three kinds of dairy products, including milk, cheese water, and yogurt water, were mixed with Acid orange 7 (AO7) as the model wastewater and used as the anolyte of an MFC. The capability of the system in energy production and dye removal was also investigated. The FESEM images were used to investigate the biofilms attachment to the anodes. Moreover, the polarization curves, electrochemical impedance spectroscopy, cyclic voltammetry (CV), voltage–time profiles, and coulombic efficiency were used to evaluate the electrochemical activity of the MFCs. Based on the CV results, the biofilm formation significantly improved the electrochemical activity of the electrodes. Maximum power density, voltage, and coulombic efficiency were obtained as 44.05 mW.m−2, 332.4 mV, and 1.76%, respectively, for cheese water + AO7 anolyte, but the milk + AO7 MFC produced a stable voltage for a long time and its performance was similar to the cheese water + AO7 anolyte. Maximum COD removal and decolorization efficiencies were obtained equal to 84.57 and 92.18% for yogurt water + AO7 and cheese water + AO7 anolytes, respectively.