Enrichment of Geobacter on Anode Biofilms from Domestic Wastewater without Posing Anode Potential in Microbial Electrochemical Cells

Microbial electrochemical cells (MxCs) offer a sustainable approach for wastewater treatment and energy recovery by harnessing the electroactive properties of microorganisms. This study explores the enrichment of Geobacter species on anode biofilms in single-(S-MxCs) and double-chambered (D-MxCs) MxCs, using domestic wastewater without an external anode potential. Stable current densities were achieved within 10 days for S-MxCs (9.52 ± 0.8 A/m2) and 14 days for D-MxCs (4.28 ± 0.9 A/m2), with S-MxCs showing a superior electrochemical performance. Hydrogen production rates were higher in D-MxCs (14.93 ± 0.66 mmol H2/L/day) compared to S-MxCs (9.46 ± 0.8 mmol H2/L/day), with cumulative production rates of 12.9 ± 1.3 mmol H2/g COD and 6.48 ± 1.4 mmol H2/g COD, respectively. Cyclic voltammetry confirmed enhanced bioelectrocatalytic activity in S-MxCs, while SEM imaging showed denser biofilms on S-MxC anodes. The novelty of this study lies in its demonstration of efficient biofilm development and microbial community resilience under non-potentialized conditions, providing insights that advance the practical application of MxCs in environmental biotechnology.