Steam pretreatment of Bougainvillea biomass for enhanced bioelectricity generation and TDS reduction in microbial fuel cells

Abstract This study evaluates the effect of steam-assisted pretreatment of Bougainvillea biomass on bioelectricity generation and wastewater treatment in microbial fuel cells (MFCs) utilizing reverse osmosis (RO) reject water as the electrolyte. Bougainvillea , an underutilized lignocellulosic ornamental plant waste, is naturally resistant to microbial degradation due to its high lignin content. To enhance its biodegradability, the biomass was steam-treated at 121 °C and 15 psi for 30 min, resulting in increased porosity and improved microbial accessibility. Both untreated and pretreated biomass were tested as substrates in dual-chamber MFCs inoculated with a pure Pseudomonas aeruginosa (P. aeruginosa ), with RO reject water (total dissolved solids (TDS)—655 ± 23 mg/L) serving as the catholyte. Electrochemical characterization through cyclic voltammetry and impedance spectroscopy revealed enhanced redox activity and significantly reduced internal resistance in the system fed with steam-treated biomass. This setup achieved a peak power density of 275 mW/m 2 and reduced TDS to ~ 200 mg/L within five days. Fourier Transform Infrared Spectroscopy (FTIR) and microscopy analyses confirmed structural degradation of the lignocellulosic matrix. Moreover, the release of reducing sugars peaked at 215 mg/g, indicating enhanced substrate bioavailability. These findings demonstrate that steam pretreatment is an effective, low-cost strategy to improve both energy recovery and TDS wastewater remediation in MFCs, promoting a sustainable approach to biomass valorization and environmental management. Graphical abstract