Characterization and identification of potential microbial fuel cells capable for the detoxification of hexavalent chromium from leather industry wastewater with power generation

Abstract

Microbial fuel cells (MFCs) are a potential green technology that might produce bioelectricity while treating wastewater and reducing heavy metal (Cr⁶⁺) pollution. A dual-chamber MFC is inoculated with potentially active bacteria to reduce Cr⁶⁺ and generate bioelectricity. Three bacterial isolates, Pseudomonas stutzeri (CSDEM1), Microbacterium algeriense (CSDEM3), and Bacillus stratosphericus (CSDEM4), were tested for their efficiency. Among these, CSDEM3 (M. algeriense) showed the highest ability to reduce Cr⁶⁺ (80.13%) at a concentration of 1500 ppm and produced the highest bioelectricity (302 mV and 501 µA), which is the novelty of this work. Bacterial cells exposed to Cr⁶⁺ displayed larger cell size than unexposed cells. Chromium peaks in exposed cells were verified by energy dispersive X-ray (EDX) analysis, suggesting that either precipitated Cr³⁺ or its complexation with bacterial cell components was the cause. The electrogenic mechanism used by the isolates, single strain, and consortia (CSDEM134) in the MFCs was revealed by the anodic biofilm generation yield. When compared to a single strain, the use of bacterial consortia in MFCs produced slightly better effluent physicochemical characteristics as well as improved Fourier transform infrared spectrophotometric (FT-IR) and Gas chromatography–mass spectrometry (GC-MS) analytical results. This study demonstrates how MFCs can remove Cr⁶⁺ from wastewater effectively and sustainably while producing sustainable bioelectricity.