Bioelectrochemical degradation of pollutants in wastewater using a dual-chamber microbial fuel cell with graphene-modified electrodes and electroactive bacteria

Abstract

The increasing discharge of pharmaceuticals and nitrates into aquatic environments poses significant ecological and public health risks, as conventional wastewater treatment plants often fail to achieve complete removal. Microbial fuel cells (MFCs) offer a bioelectrochemical approach for simultaneous wastewater treatment and energy generation; however, their efficiency is constrained by slow electron transfer. This study investigated the bioelectrochemical degradation of pharmaceuticals and nitrates in wastewater using a dual-chamber MFC equipped with graphene-coated carbon cloth anodes to enhance microbial electron transfer. Wastewater samples were collected from a municipal treatment plant and a pharmaceutical discharge site, while electroactive bac teria enriched from anaerobic sludge served as biocatalysts. Pollutant degradation was analyzed using highperformance liquid chromatography (HPLC) and ion chromatography (IC), and electrochemical performance was assessed through open-circuit voltage (OCV), power density, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results demonstrated that graphene-coated anodes enhanced pharmaceutical degradation from 62.3 % to 87.6 % and nitrate removal from 58.4 % to 83.2 % over 72 hours. Power density increased by 93.6 % (from 405.6 mW/m2 to 785.3 mW/m2 ), while internal resistance decreased by 37.5 %, indicating improved electron transfer. Biofilm analysis revealed a 55.9 % increase in thickness and a 48.3 % higher microbial cell density on graphene-coated anodes, with metagenomic sequencing confirming the domi nance of Geobacter and Shewanella. These findings highlight the potential of graphene-modified MFCs as a sus tainable and scalable technology for real wastewater treatment.