A bio-electro-Fenton system with a facile anti-biofouling air cathode for efficient degradation of landfill leachate.

Bio-electro-Fenton (BEF) system holds great potential for sustainable degradation of refractory organics. Activated carbon (AC) air cathode was modified by co-pyrolyzing of AC with glucose and doping with nano-zero-valent iron (denoted as nZVI@MAC) in order to promote two-electron oxygen reduction reaction (2e- ORR) for enhanced oxidizing performance. Single chamber microbial fuel cells (SCMFCs) with nZVI@MAC cathode was examined to degrade landfill leachate. It was revealed that nZVI@MAC cathode SCMFC showed higher degradation efficiency towards landfill leachate. Six landfill leachate treatment cycles indicated that nZVI@MAC cathode SCMFC exhibited higher COD removal efficiencies over AC and nZVI@AC and greatly enhanced columbic efficiency compared to AC and nZVI@AC cathode. Anti-biofouling effect was found on nZVI@MAC cathode because of the high Fenton oxidation effects at the vicinity of the cathode. Electrochemical characterizations indicated that MAC cathode had superior 2e- ORR capability than AC and nZVI@AC cathode, which was further evidenced by higher H2O2 production from nZVI@MAC cathode in SCMFC. Graphitic structure of MAC was evidenced by High Resolution Transmission Electron Microscopy, and glucose pyrolysis also resulted in nano carbon spheres on the activated carbon skeletons. Raman spectra indicated more defects were generated on MAC during its co-pyrolyzation with glucose.