3D Printed Spacer Design for Reverse Osmosis and Nanofiltration: Optimizing Structural Parameters to Enhance Membrane Performance

Membrane-based techniques have been playing an important role in desalination. The feed spacer in membrane modules not only separates membrane sheets to form feed channels but also acts as a turbulence promoter, enhancing flow mixing, mass transfer, and thereby reducing concentration polarization. Optimizing feed spacer design is essential for controlling the membrane fouling and lowering the energy consumption. In this study computational fluid dynamics (CFD) was exploited to optimize spacer configurations; 3D printing was employed to fabricate spacer in terms of the novel designs inspired by airplane wing aerodynamics; fluid dynamics experiments were performed to assess their effects on the flow parameters. The relationship between the flow parameters, membrane hydraulic performance, and anti-fouling properties was analyzed to reveal a trade-off between the pressure-drop reduction and fouling resistance. The design comparison indicated that wing-like designs had minimal impact on membrane permeability, while COM-M1 and COM-M2 increased reverse osmosis (RO) membrane flux by up to 19.8%. Fouling experiments further demonstrated that nanofiltration (NF) membranes, with looser separation layers, could be more prone to concentration polarization thanRO membranes, particularly after humic acid fouling. All these findings offer a basis for feed spacer optimization and provide critical insights for matching the spacer design with different membrane processes.