Interplay of Dye Biodegradation and Energy Recovery in a Microbial Fuel Cell with a MnO₂-Modified Anode under Optimized Conditions

Abstract

In microbial fuel cells (MFCs), Klebsiella pneumoniae and Pseudomonas aeruginosa bacterial coculture was used to generate energy and to degrade various concentrations of malachite green (MG) dye. The performance of MFCs was examined using electrochemical techniques under variation in operating conditions. During operation, K. pneumoniae can degrade 98.4% dye after a 36-h incubation period at pH 7 under an optimized MG concentration of 200 mg/L. A maximum power of 8.2 W/m3 was attained by 1:1 coculture of Klebsiella pneumoniae and Pseudomonas aeruginosa at 200 mg/L MG concentration. Anode modification with 2 mg/cm2 manganese dioxide (MnO2) loading showed an improvement in surface area and enhancement of electron transfer, which resulted in a power density of 12.6 W/m3. The electrochemical analysis also supported improvement in electrogenic biofilm development and electron transfer with anode modification, which can be suitable for the long-term operation of MFCs. Therefore, the interplay of dye removal and energy recovery can be optimized with process parameters and anode modification in MFCs. Microbial fuel cells (MFCs) utilizing a coculture of Klebsiella pneumoniae and Pseudomonas aeruginosa offer a practical solution for degrading toxic dyes like malachite green in industrial wastewater while simultaneously generating electricity. This approach is particularly effective with the use of MnO2-modified anodes, which significantly improve electron transfer efficiency during the microbial degradation process. MnO2 nanoparticles provide a conducive surface for bacterial biofilm formation and facilitate effective electron flow from the dye degradation reactions to the anode. As a result, the MFC not only breaks down malachite green into nontoxic by-products, reducing environmental pollution, but also captures the released electrons to produce electricity. This dual functionality makes MFCs an attractive option for industries looking to implement sustainable wastewater treatment solutions. By integrating MFC technology with existing wastewater treatment systems, industries can achieve effective dye removal, while offsetting energy costs through the electricity generated, thereby enhancing both environmental and economic sustainability.