Stacking of microbial fuel cells with continuous mode operation for higher bioelectrogenic activity

Area of Science:

• Environmental Science
• Electrochemistry
• Biotechnology

Background:

• Microbial fuel cells (MFCs) offer a sustainable energy source by converting organic matter into electricity.
• Optimizing MFC performance for stable and high power output remains a key challenge.
• Continuous operation and cell stacking are explored as strategies to enhance MFC efficiency.

Purpose of the Study:

• To evaluate the impact of stacking multiple microbial fuel cells (MFCs) for stable power output in continuous mode.
• To compare the performance of MFCs with different membrane types (Nafion, Terry cotton) and a membrane-less design.
• To investigate the effectiveness of series and parallel stacking configurations for maximizing voltage and power density.

Main Methods:

• Three single-chambered air cathode MFCs (CMFCs) with Nafion (CMFC_N), Terry cotton (CMFC_T) membranes, and a membrane-less (CMFC_ML) design were operated continuously.
• Individual CMFC performance was assessed for power density and chemical oxygen demand (COD) removal efficiency.
• CMFCs were stacked in series and parallel configurations to evaluate their combined output.

Main Results:

• CMFC_N demonstrated the highest power density (0.1 W/m²) and COD removal (50%), followed by CMFC_ML (0.062 W/m², 47%) and CMFC_T (0.025 W/m², 39%).
• Stacking CMFCs in parallel yielded a high power density (2.0 W/m²; 7.2 W/m³), while series stacking achieved a high voltage (1.1 V).
• Stacked MFCs exhibited more stable and higher bioelectricity generation, with reduced electron losses compared to individual units.

Conclusions:

• Continuous operation and stacking of MFCs significantly enhance stable bioelectricity output.
• Nafion-based MFCs showed superior performance, but stacking offers a viable route to scale up power generation.
• The findings highlight the potential of stacked MFCs for consistent and efficient wastewater treatment and energy recovery.