Application of a Dialysis-Based pH Control System to a Microbial Fuel Cell Using Ferric-EDTA Electron Acceptor

Abstract

A double-chamber microbial fuel cell (MFC) using ferric-EDTA chelates (Fe (III)-EDTA) as electron acceptors was developed and a dialysis-based system was introduced into the catholyte pH control in this research. In the developed MFC system, Fe (III)-EDTA was transformed into ferrous-EDTA (Fe (II)-EDTA) at cathodes, which was reused as electron acceptors after re-oxidation to Fe (III)-EDTA with a trickling filter-type oxidation column. The MFC operation using a pre-sedimented municipal wastewater revealed that the observed current density of the MFC using Fe (III)-EDTA reached 144 − 192 mA/m² that was much higher than that of the control using dissolved oxygen electron acceptors. The higher current density was attributed to the higher density of electron acceptors in the catholyte. The average coulombic efficiency of the MFC using Fe (III)-EDTA was 8.2%. When a conventional reagent-based pH control was applied, the electricity production of the MFC was deteriorated because of both the low temperature and the salt accumulation in catholyte derived from acid for pH control. On the contrary, the dialysis-based pH control successfully prevented the salt accumulation and maintained the higher current density. Thus, the introduction of Fe (III)-EDTA electron acceptors and the dialysis-based pH control system for catholyte was thought to be useful for operating the double-chamber MFC without any noble catalyst.