Sustainable Removal of Spirulina platensis Using PEG-Modified Membranes Derived from EPS Waste

The rapid proliferation of microalgae in aquatic systems poses significant environmental and public health challenges, particularly in regions lacking adequate water treatment facilities. This study reports a sustainable approach for microalgae removal through the development of low-cost membranes derived from expanded polystyrene (EPS) waste and modified with polyethylene glycol (PEG) as a pore-forming agent. Membranes were fabricated via non-solvent-induced phase separation with PEG loadings of 0–20 wt.% and characterized in terms of morphology, porosity, wettability, and hydraulic performance. Filtration efficiency was evaluated using Spirulina platensis as a model microalga. Incorporation of PEG (up to 15 wt.%) enhanced membrane porosity (77–84%), improved hydrophilicity (water contact angle reduced from 68° to 48°), and increased water flux (10.98–39.2 L·m−2·h−1), while maintaining complete microalgal rejection (100%). Optimized membranes exhibited asymmetric finger-like structures, contributing to improved permeability.