Comparative Analysis of Different Anodic Inoculum in Microbial Fuel Cell for Efficient Methylene Blue Dye Degradation

This study investigates three different inoculum sources in dual-chamber microbial fuel cells (MFCs), such as Marine Sediment (MFC-MS), Estuary Sediment (MFC-ES), and Anaerobic Sludge (MFC-AS), to compare the efficacy for Methylene Blue (MB) dye degradation and electricity generation. All the MFCs were operated under identical conditions in batch mode using synthetic wastewater containing 3000 mg/L COD made using sodium acetate. The electrochemical study reveals that MFC inoculated with marine sediment achieved maximum power density of 35 mW/m² followed by anaerobic sludge (31 mW/m²) and estuary sediment (25 mW/m²). Statistical analysis was employed to evaluate performance differences among the systems and to support result interpretation. Maximum COD removal efficiency of 75% was obtained by MFC-AS, and coulombic efficiency (CE) was higher for MFC-MS with 25%. Maximum decolorization efficiency was noted in MFC with anaerobic sludge, which obtained 96% decolorization over 96 h. Comparative and trend-based statistical evaluation confirmed the superior treatment performance of MFC-assisted systems. The phytotoxicity study revealed that the toxicity effect of dye wastewater was reduced to its maximum after treatment in the MFC system. The dominant performance of MFC-MS is due to the efficiency of the major electrogenic bacteria concentrated in the inoculum. The functional annotation using the data obtained from metagenomics reveals the presence and role of various enzymes and pathways involved.