A dynamic membrane (DM) comprises a layer of particles deposited onto a conventional membrane, which minimizes fouling of the primary membrane to enhance permeate fluxes. Because DMs are involved in adsorption, the size and material of the adsorbent significantly affect DM performance. However, the comprehensive effects of these factors on DMs remain unclear. Herein, the factors influencing DM morphology and performance were investigated by varying the size of two different DM adsorbent materials: heated aluminum oxide particles (HAOPs) and heated iron oxide particles (HIOPs), deposited on polymeric and ceramic (CE) membranes. The density of the dynamic layer increased as the adsorbent particle size decreased. All DMs exhibited approximately 30 % improved flux and higher humic acid (HA) removal efficiencies (HAOP-DM:90 %, HIOP-DM:82 %) than the virgin membranes. Adsorbent size significantly affected DM performance; a five-fold size reduction resulted in an approximately 25 % increase in HA removal. A membrane resistance model was employed to quantitatively analyze the DM performance. HIOP-DM exhibited 80 %–90 % reversible fouling, whereas HAOP-CE displayed 70 %–80 % irreversible fouling. Because reversible fouling was the dominant mechanism of HIOPs, the DMs were reused after chemical treatment. However, HAOP DMs required replacement, despite their high water flux retention and HA removal efficiency.
