Simultaneous reduction of vanadium (V) and chromium (VI) with enhanced energy recovery based on microbial fuel cell technology

Vanadium (V) and chromium (VI) are the main metals found in vanadium containing wastewater with large amount and great toxicity. In present study, reduction of V(V) and Cr(VI) together with electricity generation is successfully achieved in double chamber microbial fuel cells (MFCs) by employing vanadium containing wastewater as the cathodic electron acceptor. The V(V) and Cr(VI) reduction efficiencies for 240 h operation approach up to 67.9 ± 3.1% and 75.4 ± 1.9%, respectively, with a maximum power density of 970.2 ± 20.6 mW m−2. The power output is enhanced, compared with the results from MFCs with V(V) as the sole electron acceptor, while the decrease of the cathode efficiency caused by deposits from Cr(VI) reduction process can also be mitigated. After reduction, chromium is mainly deposited on the cathode surface in the form of Cr(III), while most of vanadium can be precipitated from the exhausted catholyte by adjusting pH, thus treating vanadium containing wastewater successfully with energy harvest based on MFC technology. The operating principles of MFCs with two different electron acceptors are also reported for the first time.

► Vanadium (V) and chromium (VI) are employed as joint cathode electron acceptors. ► The power outputs of the microbial fuel cells are enhanced. ► Vanadium containing wastewater can be successfully treated. ► Metals can be separated and recovered after being reduction.