Using dual chamber microbial fuel cells for coupled microplastic biodegradation and bioelectricity production: assessing the effect of substrate

BACKGROUND: Use of plastics has increased manifold over the last 50 years. Regrettably, their fragmentation into microplastics (MPs) (≤ 5 mm) created environmental and human health concerns. Traditional methods of MPs removal are limited by high energy requirements, high costs, and the use of chemical reagents. Microbial fuel cells (MFCs) provide a sustainable solution for treating wastewater containing MPs while simultaneously generating bioelectricity. RESULTS: This study investigated the potential of a microbial consortium in an MFC setup to remediate polyethylene terephthalate microplastics (PET-MPs) from a synthetic wastewater while generating electricity. Electrochemical process, substrate functionality (i.e., glucose and acetate), and microplastic degradation were tracked. Biodegradation effectiveness was evaluated using microscopic observations, microbial growth, and CO release. The results indicated 21.4% ± 2% biodegradation of PET-MPs, with a maximum CO release of 450 ± 173.9 ppm. Scanning electron microscopy and Fourier transform spectroscopy validated the result, showing structural impairment and disruption of the MP ester functions. Acetate increased degradation by 32% ± 2%, whereas glucose increased it marginally by 22% ± 2%. Maximum power density with acetate was 8.58 mW/m², significantly higher than that generated with PET-MPs alone (0.343 mW/m²; p < 0.05), and more than 25% COD reduction in MFCs demonstrated the potential of the systems for wastewater treatment. CONCLUSIONS: This work corroborates the feasibility of applying microbial fuel cells as a green technology solution for microplastic alleviation by examining microplastic degradation processes, substrate applications for degradation effectiveness, and their superiority over conventional removal methods.