Valorization of Ulva fasciata biowaste incorporated in PVA nanofibers and films membranes: Box-Behnken optimization toward advanced wastewater treatment and blue economy applications

Abstract The removal of low-concentration pollutants from wastewater remains a major challenge in advanced treatment processes, where conventional wastewater treatment methods often underperform due to limited mass transfer and weak interaction kinetics. In this study, a novel bio-based membrane system was developed using polyvinyl alcohol (PVA) and Ulva fasciata bioethanol byproduct extract (UFBE), a waste-derived material rich in antimicrobial ulvan. Dual-format membranes, comprising nanofibers and films, were fabricated through green electrospinning and solvent-casting techniques using water-based systems. Box-Behnken response surface methodology was employed to optimize the electrospinning parameters for minimized fiber diameter and morphological uniformity. Characterization analyses (SEM, SEM-EDX, FTIR, TGA, XRD, BET, tensile strength, swelling, and solubility tests) confirmed the successful integration of UFBE and improvements in thermal and mechanical properties. The membranes were applied to aged oilfield wastewater representing a low-pollutant treatment challenge. Despite reduced contaminant levels, the membranes achieved nearly 100% oil removal, an 82% reduction in turbidity, and substantial declines in hardness and scaling potential. These findings underscore the membrane’s sensitivity, selectivity, and suitability for tertiary treatment applications. This work presents a foundational approach to developing multifunctional, sustainable membranes from algal waste, offering new opportunities for bio-derived materials in environmental remediation.