Performance of low cost scalable air–cathode microbial fuel cell made from clayware separator using multiple electrodes

• Developed low cost air cathode MFC of 26 L capacity with clayware separator.
• Fourteen months stable performance reveals viability of MFC for field applications.
• Internal resistance decreased from 19 Ω (series) to 8 Ω by parallel connection.
• Maximum power of 17.85 mW achieved at 0.375 V (47.25 mA) with 78% COD removal.
• 5.1% Coulombic efficiency is among the higher value reported for larger volume MFC.

Performance of scalable air–cathode microbial fuel cell (MFC) of 26 L volume, made from clayware cylinder with multiple electrodes, was evaluated. When electrodes were connected in parallel with 100 Ω resistance (Rext), power of 11.46 mW was produced which was 4.48 and 3.73 times higher than individual electrode pair and series connection, respectively. Coulombic efficiency of 5.10 ± 0.13% and chemical oxygen demand (COD) removal of 78.8 ± 5.52% was observed at Rext of 3 Ω. Performance under different organic loading rates (OLRs) varying from 0.75 to 6.0 g COD L−1 d−1 revealed power of 17.85 mW (47.28 mA current) at OLR of 3.0 g COD L−1 d−1. Internal resistance (Rint) of 5.2 Ω observed is among the least value reported in literature. Long term operational stability (14 months) demonstrates the technical viability of clayware MFC for practical applications and potential benefits towards wastewater treatment and electricity recovery.