Dual-chamber microbial fuel cells for oilfield produced water treatment: Insights into pollutant removal and microbial community dynamics

The treatment of oilfield produced water (OPW) using dual-chamber microbial fuel cells (MFCs) was investigated to evaluate pollutant removal efficiency and microbial community dynamics. Hydrocarbon and chemical oxygen demand (COD) degradation occurred at the anode, while aerobic nitrification was facilitated at the cathode using inoculated nitrifying sludge. Over 180 days of operation, the system achieved 71.14 % COD and 70.68 % total petroleum hydrocarbons (TPHs) removal at the anode, and 75.96 % ammonia nitrogen (NH₄⁺-N) removal at the cathode. Electrochemical performance stabilized at 360.42 mV, with a peak power density of 149.38 mW/m². Microbial diversity analysis showed functional specialization: Shewanella dominated anode for electron transfer, while Nitrosococcus enriched cathode for nitrification. Co-expression network analysis highlighted increased connectivity and robustness at the cathode, suggesting enhanced stability in microbial interactions over time. The modular structure of microbial networks demonstrated key functional shifts, correlating with pollutant removal performance. These findings highlight the synergy between redox-specific microbial processes and establish dual-chamber MFCs as a promising solution for sustainable OPW treatment.