Comparative study of fouling in hollow fiber and flat sheet nanofiltration membranes by three organic foulants: Insights into configuration impact on fouling

Hollow fiber (HF) membrane modules offer potential advantages over spiral-wound membrane modules in terms of fouling control due to the absence of spacers. This study investigated the fouling behavior of sodium alginate (SA), bovine serum albumin (BSA), and humic acid (HA) on NF90 flat sheet membranes and HF nanofiltration (NF) membranes through three cycles of fouling-cleaning experiments. Results showed that HF NF membranes exhibited lower total fouling and higher flux recovery ratio at the beginning in the HA and BSA fouling, but fouling rates were similar to those of NF90 flat sheet membranes. HF NF membranes showed higher fouling resistance for SA fouling, specifically in their lower decline of water permeability in three cycles, lower total fouling, and reduced fouling rate. Both membrane types maintained consistently high and stable rejection rates for all three foulants across all cycles. Complete blocking and cake layer formation played an important role in the fouling process. The observed difference in the fouling mechanism for the same foulant between the two membrane configurations confirmed the influence of membrane geometry on fouling dynamics. This research provides a further understanding of the advantages of HF NF membranes in mitigating membrane fouling, offering valuable information for membrane product selection in various applications.