Condensate originating from household food waste as a substrate for Microbial Fuel Cells

A microbial fuel cell (MFC) is a bioreactor that converts the chemical energy of the bonds of organic compounds to electrical energy, through the catalytic reactions of microorganisms. Under anaerobic conditions various substrates have been examined using MFC technology. This study examines the potential use of the liquid fraction of fermentable household waste (source-sorted food waste), which results from condensation of the vapors generated during drying, as a feed to the MFC. The main characteristics of this substrate are: 13 g COD/L, pH=3.5, conductivity=262 μS/cm. Condensate was fed to two single-chamber air cathode MFCs, using mullite and GoreTex as cathodic electrodes, respectively. The oxygen reduction catalyst was MnO2 in both cases, while graphite granules were used as anodic electrodes. The units were operated in batch mode. Linear sweep voltammetry was carried out in order to conduct electrochemical characterization. The maximum power output was 0.52 μW/m3 for the mullite cell and 0.28 μW/m3 for the GoreTex cell, respectively. High COD removal efficiencies (>75%) were achieved for both cells.