The impact of feed spacer design on membrane fouling mechanism in ultrafiltration (UF) process under constant flux mode was systematically investigated. Thecombined intermediate pore blocking and cake filtration model was employed,coupled with experimental crossflow UF experiments of dextran and sodium alginate (SA) in aqueous feed solutions. Filtration resultsofthree different spacer geometries, which included two 3D-printed spacers based on triply periodic minimal surfaces (TPMS) (Gyroid and TCLP) and one commercial net-type spacer, were analyzed. Flux-stepping tests were performed to determine the threshold flux (TF) in each case. Experimental data were fitted using the filtration model and the results were evaluated in terms of cake filtration constant (Kc, m−1), rate of cake erosion (S, kg.m−2.s−1), particle resuspension rate (B, s−1), and specific cake resistance (α, m.kg−1), in order to understand the cake formation and erosionbehavior that is influenced by the spacer geometry. A difference in spacer performance was observed when the solute was changed from SA to dextran. The results demonstrated that spacer design has a significant effect on the fouling mechanism in UF separation. The TCLP spacer is able to operate at the intermediate pore blocking mechanism at higher fluxes compared to the net-type spacer for both solutes tested. The flow hydrodynamics induced by the spacer geometry influenced the re-suspension rate of the deposited particles in the filtration cake. Additionally, combination of spacer surface roughness and solute molecular sizes were found to be the significant factors in cake-buildup on the spacer and the membrane.
Bibliographical noteFunding Information:
This work was supported by Korea Environment Industry & Technology Institute (KEITI) through Industrial Facilities & Infrastructure Research Program, funded by Korea Ministry of Environment (MOE) (116953).This study was also funded by the Center for Membrane and Advanced Water Technology (CMAT) at Khalifa University, under Award No. RC2-2018-009. We thank Dr. Reza Rowshan and Dr. Oraib Al-Ketan for their valuable assistance in printing the TPMS spacers. TPMS spacers were printed using Core Technology Platform resources at NYU Abu Dhabi. We are also thankful for the earlier collaboration we had with Prof. Rashid Abu Al Rub from Khalifa University, which has previously led to the development of TPMS spacers.
© 2022 Elsevier B.V.
- Constant flux
- Feed spacer
- Fouling mechanism
- Triply periodic minimal surfaces
ASJC Scopus subject areas
- General Chemistry
- Environmental Chemistry
- General Chemical Engineering
- Industrial and Manufacturing Engineering