Exploitation of Digestate from Thermophilic and Mesophilic Anaerobic Digesters Fed with Fermentable Food Waste Using the MFC Technology

Abstract

This study reports on the investigation of the digestate treatment using microbial fuel cell (MFC) technology. The effluents from a thermophilic and a mesophilic anaerobic digester, fed with fermentable household food waste (FORBI), were characterized and used as the feed in four air–cathode MFC units. The chemical oxygen demand (COD) removal ranged from 80% to 90% and was achieved within the first 24 h to 48 h of each cycle operation, although electricity was still produced for more than 190 h. The electrochemical characterization of the cells showed low internal resistances (10–50 Ω) of the units for both inlets. The maximum power output of the mesophilic fed cells (~ 0.24 mW) is lower in comparison with the respective power achieved from the thermophilic fed cells (~ 0.42 mW). The work demonstrated the potential of using MFC technology to further treat and exploit anaerobic digestates which are produced from FORBI.