Reduction of chromium(VI) with energy recovery using microbial fuel cell technology

A simple microbial fuel cell (MFC) method for the reduction of hexavalent chromium (Cr6+) at an abiotic cathode by using an exoelectrogenic biofilm on the biotic anode, has been established. Two different Cr6+-containing effluents were synthetically prepared in the laboratory (4 and 8 mgl(-1)). The chromium effluents were used as catholyte and anaerobic microorganisms as anodic biocatalyst. 4 mgl(-1) of Cr 6 + was reduced 95% while, 8 mgl(-1) reduced 86% during 456 h reaction in the MFC systems investigated. The MFC system with 4 mgl(-1) of chromium exhibited a maximum power density of 89 +/- 3 mW m(-2) and a maximum voltage of 931 mV. A power density of 69.5 +/- 2.1 mW m(-2) and voltage of 700 mV was obtained by 8 mgl(-1) chromium containing MFC cell. This work verifies the possibility of current production and simultaneous cathodic Cr6+ reduction. The novelty and significance of this system is that it uses an uncomplicated and economical salt bridge which replaces costly membranes like Nafion and an abiotic cathode. (C) 2016 Elsevier Ltd. All rights reserved.