| Abstract | Microplastics pose a significant threat to marine ecosystems, affecting air and water quality, food resources, and broader ecological processes. The detection of plastics in the human placenta and their potential link to cardiovascular diseases further intensifies concerns. To address this issue, bacteria could be exploited to degrade plastics while simultaneously upcycling the by-products into value-added products such as bioenergy. However, anaerobic biodegradation of plastics—critical for waste management systems like wastewater treatment and landfills—remains poorly understood. This study explores how various pre-treatment techniques enhance the anaerobic biodegradation of polyethylene terephthalate (PET), one of the most used types of plastic, and evaluates its potential for conversion into electricity using microbial fuel cells (MFCs), thus integrating waste management with renewable energy production. The impact of different pre-treatment methods—UV, thermal, and chemical—on PET biodegradation in MFC-oriented anaerobic environments was investigated. PET surface modifications were analysed using Fourier transform infrared spectroscopy (FTIR), while degradation efficiency was assessed via weight loss studies and analytical techniques such as high-performance liquid chromatography (HPLC) and gas chromatography–mass spectrometry (GC-MS). Among the tested pre-treatment methods, UV-treated PET exhibited the highest biodegradation efficiency, with a weight loss of 29.2% over 40 days. Comparatively, heat-treated PET, chemically treated PET, non-treated PET with microorganisms, and non-treated PET without microorganisms exhibited degradation efficiencies of 21.4%, 20.5%, 11.7%, and 1.3%, respectively. FTIR analysis revealed a reduction in the ester bond, with a notable peak at 1714 cm⁻¹ (C=O stretching of the ester group), suggesting the formation of carbonyl-containing oxidation products in UV-treated PET after 40 days. Additional changes in crystallinity and ester hydrolysis were indicated by peak intensity changes at 1240 cm⁻¹. Ethanol and other degradation products were detected through GC-MS and HPLC. MFC performance analysis demonstrated that electricity generation coincided with PET biodegradation. The MFCs fed with UV-treated PET achieved a closed-circuit voltage ranging from 25 mV to 186 mV across a 2200-ohm external resistor, with an anode electrode size of 25 cm². The highest power density (1.14 mW m⁻²) and current density (5.7 mAm⁻²) were recorded for UV-treated PET. In comparison, chemically treated PET, heat-treated PET, non-treated PET with microorganisms, and non-treated PET without microorganisms exhibited maximum power densities of 0.28 mWm⁻², 0.55 mWm⁻², 0.20 mWm⁻², and 0.13 mWm⁻², respectively. This study provides valuable insights into the potential for upcycling synthetic polymers into useful products, demonstrating that UV pre-treatment enhances PET biodegradation and energy (electricity) recovery under anaerobic conditions. These findings have implications for a more sustainable, circular economy by integrating plastic waste management with bioenergy production. |
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