Synergistically controlling biofouling and improving membrane module permeability by using simultaneously structurally optimized and surface modified feed spacers

This study developed a new protocol to prepare feed spacers in the membrane module , by combining the optimization of spacers' geometrical parameters with subsequent chemical modification of the spacers’ surface, to enhance filtration performance comprehensively. Geometrical parameters of columnar spacers were optimized using an object-oriented and automatic optimization method based on computational fluid dynamics (CFD) simulation coupled with response surface optimization. In chemical modification, polydopamine was firstly used to provide anti-adhesive properties, followed by the even integration of silver nanoparticles (AgNPs) to exhibit antimicrobial activity. Anti-biofouling experiments involving Gram-negative ( E. coli ) and Gram-positive ( S. aureus ) bacteria demonstrated that the combined structurally optimized and chemically modified spacers resulted in over 10 % improvement in permeate flux and a 27 % reduction in feed channel pressure (FCP) drop. Chemical modification enhanced the structural optimization resistance to flux attenuation and FCP drop increase by over 220 % and 200 %, respectively. Analysis of the anti-biofouling behavior indicated that the primary mechanism of the integrated, optimized spacers lies in the increased wall shear , bactericidal activity of AgNPs, and improved interfacial interaction energy between the spacers and foulants. This study not only developed a novel modification method for anti-biofouling spacers, but also provides in-depth understanding of the roles of modified spacers, all of which are important for their practical applications in improving membrane filtration performance.