Application of multi-bore hollow fiber membranes for improved fouling behavior in MBR and enhanced wastewater treatment efficiency

Membrane fouling remains the primary limitation of membrane bioreactors (MBRs), resulting in flux decline and frequent cleaning. Although hollow fiber membranes are extensively applied in MBR systems, the effect of fiber geometry on fouling behavior has not been systematically clarified. This study presents a controlled bench-scale comparison of single-bore and multi-bore PVDF hollow fiber membranes operated in identical submerged MBRs treating synthetic municipal wastewater. Both systems achieved nearly complete COD removal, confirming comparable biological performance regardless of membrane configuration. However, the multi-bore/MBR demonstrated markedly improved fouling resistance, extending the operational period required to reach the critical TMP of 30 kPa from 14 days (single-bore) to 31 days. Quantitative measurements revealed a substantial reduction in loosely bound extracellular polymeric substances (LB-EPS) in the cake layer (≈80 vs. 200 mg/gVSS), while tightly bound EPS (TB-EPS) showed only minor variation. FTIR and EEM fluorescence analysis confirmed lower accumulation of protein-like and humic-like compounds on the multi-bore membrane surface. This study provides comprehensive experimental insight into the influence of hollow-fiber membrane configuration on fouling behavior in MBR systems, contributing to the understanding of how membrane module design affects operational stability and fouling development.