A novel microbial fuel cell design as biosensor to evaluate biochemical oxygen demand

Microbial fuel cell (MFC) technology has gained significant attention for its dual capability to generate renewable energy and treat wastewater. Beyond these applications, MFCs have emerged as a promising tool for biosensing, particularly for detecting water pollutants. In this study, we aimed to optimize the evaluation of biochemical oxygen demand (BOD) by correlating it with the output voltage of an MFC. The effects of pH and external resistance on the MFC's performance were also assessed to enhance its operational stability. The experiment utilized a two-chambered MFC with a 2500 mL capacity, ceramic membrane, and carbon cloth electrodes. Synthetic wastewater and Shewanella xiamensis (code SH1 MF663195) were used as the anolyte, while distilled water served as the catholyte. Over 7 weeks, the MFC achieved a maximum current density of 1.939 mA/m 2 and a power density of 80 mW/m 2 at near-neutral pH and 3 kΩ external resistance. A positive linear correlation (R 2 = 0.9984) was established between the output voltage and BOD concentration (16–436 mg/L). These findings suggest that this MFC-based biosensor is highly feasible and holds significant potential for real-time water quality monitoring. • MFC-based biosensor offers a sustainable cheap solution for real-time BOD detection • Dual-chamber MFC uses synthetic wastewater anolyte and distilled water catholyte • Voltage output correlates strongly with BOD levels for accurate monitoring • Biosensor stability maintained over 30 days at near-neutral pH