Valorization of palm petiole waste as natural biocoagulants: Optimizing coagulation-flocculation for sustainable wastewater treatment and advancing circular economy in agriculture

This study investigates the potential of palm petiole waste (PPW) and its extracted lignin as natural biocoagulants for removing methylene blue, crystal violet dyes, and turbidity from wastewater. Comprehensive characterization using X-ray diffraction, fourier-transform infrared spectroscopy, scanning electron microscopy coupling with energy-dispersive X-ray spectroscopy, X-ray fluorescence, and elemental analysis revealed the distinct physicochemical properties of PPW and lignin. A Box-Behnken experimental design optimized coagulation conditions, achieving 98.26 % pollutant removal with PPW and 90.17 % with lignin. Crucially, PPW's superior performance stems from a synergy of adsorption, charge neutralization by metal salts, and bridging effects, while lignin relies primarily on adsorption and bridging. This challenges the notion that lignin alone dictates coagulation efficacy in lignocellulosic wastes. The study also explored the economic and environmental implications of using PPW as a bio coagulants-flocculant, demonstrating significant reductions in carbon footprint, energy consumption, and water use compared to conventional chemical coagulants.