Divergent Hydrodynamic Impacts of Feed Spacer Designs on Scaling and Biofouling in Spiral Wound Membrane Modules

Spiral wound membrane (SWM) modules are vital for water purification technologies but suffer from performance degradation caused by membrane fouling. Existing studies on SWM feed spacer designs predominantly target single-type fouling mitigation (e.g., biofouling), lacking cross-comparative assessment of different fouling challenges. This study investigates how geometric modifications of columnar-node feed spacers regulate hydrodynamic conditions to combat inorganic scaling and biofouling differentially via combined numerical and experimental approaches. Our results reveal that spacer architectures dictate resistance to fouling through divergent hydrodynamic mediation pathways. The triangular mesh configurations demonstrated superior scaling mitigation performance by enhancing shear stress and solute mass transfer efficiency to suppress concentration polarization, while the diamond-shaped columnar-node design effectively minimized biofouling through reduced hydraulic stagnant zones that typically facilitate microbial adhesion. The hexagonal architectures exacerbated both fouling types due to inadequate fluid mixing, highlighting critical trade-offs between turbulence generation and hydraulic resistance. Overall, the spacer design for scaling control should enhance mass transfer efficiency, while that for biofouling inhibition is suggested to diminish the proportion of low-velocity regions in the feed channel. These insights establish a mechanistic foundation for developing specialized feed spacers that target dominant fouling challenges, advancing the rational design of SWM modules across diverse water treatment applications.