Use of Anaerobic Sludge Microbial Consortia in a Microbial Fuel Cell Biosensor for Biochemical Oxygen Demand...

Effective management of wastewater treatment plants often requires real-time measurements of Biochemical Oxygen Demand (BOD). Conventional methods for determining Biochemical Oxygen Demand (BOD) are often time-consuming, labor-intensive and prone to inaccuracies. Microbial Fuel Cells (MFCs) have emerged as a viable alternative technology for BOD measurement, offering real-time monitoring capability. However, challenges remain in its validity for testing different types of wastewater. This study developed a cost-effective dual-chamber MFC with graphite felt electrodes and a CMI-7000 membrane, inoculated with a microbial consortia grown from anaerobic sludge at optimal conditions (35 °C, pH 7, 1000 Ω external resistance). After one month of biofilm formation, the MFC produced 600 mV. Voltage outputs were measured at six BOD₅ concentrations (36 to 583 mg/L) in synthetic wastewater, showing a strong linear correlation between BOD₅ concentrations and voltage outputs. The MFC was also tested with five domestic wastewater samples with BOD₅ values ranging between 81 and 405 mg/L. The output voltages were inserted into the derived voltage-BOD correlation to obtain BOD₅ values within 2.5% to 11% of conventional laboratory results. These findings confirm the potential of MFC-based biosensors as an efficient and accurate tool for real-time wastewater monitoring.