Optimization of the Eco-Friendly Surface Modification of PES Hollow Fiber Membranes for Advanced MBR Performance

This study addresses membrane biofouling in poly(ether sulfone) (PES) hollow fiber membranes through an eco-friendly surface modification aimed at improving hydraulic performance during membrane bioreactor (MBR) operation. Mussel-inspired polydopamine (PDA) was deposited on PES membranes and integrated with in situ synthesized zinc oxide nanoparticles (ZnO NPs) via a green synthesis modification. Key parameters of membrane surface modification were optimized by using response surface methodology (RSM). Membrane hydrophilicity, porosity, permeability, and critical flux were evaluated through water contact angle measurements, porosity analysis, and hydraulic performance testing. Surface SEM and EDS analysis determined the appropriate polymerization time and synthesis parameters, while FT-IR, Raman spectroscopy, and TGA confirmed successful surface modification. The optimal conditions─1 h PDA polymerization, 0.01 mol·L–1 zinc acetate, and 1 h ZnO synthesis─yielded in the approximately 21% increase in permeability (295 L·m–2·h–1·bar–1) and 56% for critical flux (20 L·m–2·h–1) compared to non-optimized modified membranes. ICP analysis confirmed the stability of the immobilized ZnO NPs during filtration. Antibiofouling performance of modified membrane was proven by limited (after 5 h) and no (after 24 h) growth of Escherichia coli and Staphylococcus sp. The findings demonstrate an effective modification strategy for enhancing the PES hollow fiber membrane performance in MBRs.