Highly effective controlling biofouling and sustaining feed channel pressure by a well-designed spacer based on mechanistic analysis of microbial deposition in a spiral wound nanofiltration

Biofouling in spiral-wound membrane modules (SWMs) severely compromises separation efficiency and lifespan, limiting their cost-effective application. As a core component of SWMs, feed spacers mitigate fouling by promoting turbulence and enhancing shear forces. Building upon prior development of an optimized feed spacer (OPT-FS) via computational fluid dynamics (CFD) modeling and response surface methodology (RSM), this study further experimentally validated its anti-fouling performance and mechanisms. Comparative experiments using P. aeruginosa and S. aureus demonstrated OPT-FS's efficacy, which reduced the average flux decline by approximately 5.5 %, energy consumption by 18–21 %, and surface coverage (TOC/ATP) by 10–30 % versus standard feed spacers (STD-FS). Mechanistically, OPT-FS elevated minimum bacterial shear stress by 7 %, inhibiting deposition. In complex water matrixes with humic acid (HA), sodium alginate (SA) and bovine serum albumin (BSA), OPT-FS significantly decreased flux decline by about 10 %, energy consumption by about 65 %, and organic deposition by about 25–40 % compared with STD-FS. These improvements were substantiated through shear stress analysis and XDLVO theory. Moreover, actual wastewater treatment confirmed the multifunctional anti-fouling role and potential of OPT-FS for enhancing SWM system sustainability.