Sustainable wastewater treatments and energy production utilizing microbial fuel cells: A detailed review on advanced technologies

Globally, wastewater is considered a major environmental issue and causes numerous health problems. Every year, the amount of wastewater generated increases due to human activities such as industrialization, overpopulation, and urban growth. Wastewater treatment has traditionally used conventional methods, including coagulation, flocculation, sedimentation, oxidation, and filtration. However, the common aerobic treatment process consumes more energy. Researchers are actively developing new techniques that are low-cost, energy-producing, capable of recovering valuable substances, and able to recycle treated water. In this context, MFCs have been widely studied for generating electrical energy from wastewater by converting the chemical energy of pollutants through microbial catalytic activity in anaerobic conditions. MFCs can simultaneously treat wastewater, generate bioelectricity, and enable the recovery of valuable resources such as nutrients (e.g., phosphorus and nitrogen) and metals (e.g., copper, chromium, and silver) through bio-electrochemical reduction, microbial metabolism, and electrochemical precipitation processes. Thus, the improvements in MFC design have led to significant advances in wastewater treatment. This review offers an overview of the latest MFC designs, their mechanisms, and factors influencing performance, along with their applications in wastewater and leachate treatment. It discusses advanced techniques used for industrial, pharmaceutical, domestic wastewater, and leachate treatment with MFCs. Additionally, recent hybrid reactors, computational intelligence, and key challenges in developing efficient MFCs are examined. This article aims to provide young researchers, scientists, and engineers working in this field with a clear overview of MFC technology and outline future research directions for large-scale practical applications.