Electrochemical Modeling of Bioenergy Generation from Wastewater by Microbial Fuel Cells

Abstract

As global water scarcity and environmental pollution continue to escalate, innovative wastewater treatment technologies are needed to ensure sustainable water resource management. Conventional wastewater treatment methods, such as activated sludge processes, are energy-intensive, costly, and contribute significantly to greenhouse gas emissions. Microbial fuel cells (MFCs) present a promising alternative, harnessing electroactive bacteria to simultaneously degrade organic pollutants and generate electricity. By leveraging microbial metabolism, MFCs can convert chemical energy in wastewater into usable electrical energy, offering a dual benefit of pollution reduction and renewable energy production. This study focuses on developing a numerical simulation framework to optimize MFC performance, with an emphasis on real-world application at the Guelph Water Resource Recovery Centre (WRRC). A steady-state microbial fuel cell model was developed and validated using experimental data from previous studies. The model employs a finite difference method to solve mass balance equations for key reactants and products, including acetate, dissolved CO₂, protons, and oxygen. The simulation results highlight the influence of various operational parameters—such as substrate concentration, internal resistance, wastewater flow rate, and temperature—on the performance of a dual-chamber MFC. The study further compares MFC efficiency with conventional wastewater treatment processes, demonstrating a significantly higher chemical oxygen demand (COD) removal rate in MFCs (0.0633 kg COD/m³/day), which is approximately 4.7 times greater than that observed at the WRRC. The results emphasize the role of microbial activity and electrochemical interactions in optimizing power generation and pollutant degradation. Key limitations such as oxygen transport restrictions, internal resistance, and pH imbalances were identified, suggesting areas for improvement in MFC design. Numerical simulations were further extended to model full-scale integration within WRRC, providing insights into the feasibility of MFC technology as an alternative treatment strategy. Despite challenges in large-scale deployment, MFCs show strong potential for reducing wastewater treatment energy demands and mitigating environmental impacts. This research contributes to the advancement of MFC applications in wastewater treatment by demonstrating the effectiveness of numerical modeling in predicting and optimizing system performance.