ZnO-Modified Carboxymethyl Cellulose Hydrogels for Sustainable Control of Fat, Oil, and Grease Deposition in Sewer Systems

Fatberg formation poses a critical challenge to urban wastewater infrastructure, necessitating adaptive and smart materials for effective control. This study presents a novel composite hydrogel, carboxymethyl cellulose (CMC)-based hydrogel beads reinforced with zinc oxide (ZnO), designed to mitigate fat, oil, and grease (FOG) accumulation in sewer systems. The hydrogel was synthesized via ionic cross-linking. The CMC matrix contributes hydrophilicity, biocompatibility, swelling ability, and a porous three-dimensional framework that facilitates physical entrapment and retention of the FOG components. The incorporation of ZnO enhances the mechanical robustness, structural stability, surface roughness, and interfacial reactivity, collectively promoting effective interaction, destabilization, and redistribution of fatty deposits within the hydrogel matrix. The hydrogel beads exhibited negative ζ-potentials (−26.86 mV before exposure and −4.68 mV after exposure), confirming colloidal stability and favorable surface charge for FOG interaction. ZnO@CMC beads demonstrated long-term durability, retaining uniform spherical morphology, rough surface texture, high porosity, and excellent water-retention capacity after three months of immersion in wastewater. Remarkably, they achieved FOG deposition efficiencies of 56.74% under air-dried conditions and 64.83% under freeze-dried conditions. This work introduces a sustainable and high-performance hydrogel platform for in-sewer FOG mitigation, advancing practical and environmentally responsible strategies for urban wastewater management.