Simultaneous phenol removal and electricity generation using a hybrid granular activated carbon adsorption-biodegradation process in a batch recycled tubular microbial fuel cell

Abstract

A microbial fuel cell (MFC) was efficiently integrated with adsorption process to remove a hardly degradable compound (phenol). For this purpose, a tubular recycled batch bioreactor was designed as a granular activated carbon (GAC) adsorption/MFC combined system (GAMFC). Effects of three important parameters, i.e. temperature, phenol concentration, and GAC dosage, on the performance of the GAMFC were investigated. Results revealed that the GAMFC could achieve an efficiency of 95% in phenol removal at optimum conditions, which was higher than the conventional MFC (75%). Additionally, power density increased to 110 mW m−2 in the presence of GAC, while for the MFC it was only 70 mW m−2. This improvement can be attributed to the role of GAC as a porous media in facilitating microbial growth as well as its contribution as an adsorbent. Experimental results in the GAMFC were simulated using a modified multi-order- Butler-Volmer equation and the inhibitory constant was 0.456 kg m−3, which was higher than the MFC at the same condition (0.17 kg m−3). Columbic efficiency calculated for the GAMFC and the MFC at optimum conditions was 45.77% and 22.13%, respectively. Furthermore, a petrochemical wastewater containing a considerable amount of phenol was fed to the MFC and GAMFC systems, to evaluate their efficiencies in a real condition. The superior performance of the GAMFC compared to the MFC was also reconfirmed in this case.