Development of a Drip-Biofilter Microbial Fuel Cell System with Air-Gap Isolation for Enhanced Wastewater Treatment and Power Generation

Abstract Traditional stacked microbial fuel cell (MFC) systems exhibit significant limitations in continuous-flow wastewater treatment due to cross-interference from interconnected anolyte solutions, leading to voltage stacking failure and impeding scale-up. To address this, a novel drip biofilter-based tubular air-cathode MFC (DB-TAC-MFC) system was developed by integrating a drip-biofilter box with a tubular air-cathode MFC and introducing an air-gap isolation design. Key innovations include: (1) a uniform drip distribution mechanism for stable mass transfer via liquid film; (2) an air-gap modular configuration (8 mm spacing) that prevents substrate cross-conduction; and (3) a synergistic 3D electrode–biofilm system using conductive filter media for electroactive microbial enrichment. Operated under an influent COD of 1100 mg/L, the three-unit DB-TAC-MFC achieved a peak voltage of 1.14 V, a volumetric power density of 5218.3 mW/m³ at 1.2 MΩ, and maintained 75% COD removal over 72 h. This design effectively resolves voltage stacking issues, enhances energy stability, and provides a scalable solution for decentralized wastewater treatment with integrated energy recovery.