Effects of heavy metals (Fe³⁺/Cr⁶⁺) on low-level energy generation in a microbial fuel cell

A dual-chamber microbial fuel cell (MFC) was constructed with Pseudomonas aeruginosa as biocatalyst to facilitate substrate conversion and, consequently, low-level energy generation. To simulate a wastewater situation with BOD and heavy metals contamination, glucose and Fe³⁺ and Cr⁶⁺ were used as substrate and heavy-metal spikes, respectively. The effects of varying substrate concentrations (150 ppm, 300 ppm, 600 ppm) and heavy metal loads (10 ppm, 50 ppm, 100 ppm) on overall power generation were evaluated. The presence of Cr⁶⁺ in the anode compartment decreased the potential from 565 to 201 mV (i.e., lowest value achieved at highest Cr⁶⁺ concentration of 300 ppm). On the other hand, replacing Cr⁶⁺ with Fe³⁺ as electron acceptor resulted in substantial increase in measured potential (i.e., from 565 to 703 mV). Increasing glucose concentrations resulted in longer time to reach constant open circuit voltage. A maximum potential of 606 mV was achieved at 1200 ppm glucose. Incorporating Pseudomonas aeruginosa increased the potential from 256 to 592 mV. On the basis of these results, a microbial fuel cell feeding on wastewater can be an important potential technology for generating low-level energy