Integration of Specific Aeration Demand (SAD) into Flux-Step Test for Submerged Membrane Bioreactor

This study proposes a novel methodology to assess fouling that complements the flux-step test (FST) by integrating aeration-step tests (ASTs) to optimise the specific aeration demand (SADm) for ultrafiltration hollow-fibre (UF-HF) submerged membranes in membrane bioreactor (MBR) configurations. Three membranes with distinct manufacturing processes-non-thermal-induced phase separation (NIPS) and thermal-induced phase separation (TIPS)-were evaluated under continuous and intermittent aeration. The AST revealed that the critical SADm has a range of 0.1-0.5 m³·m^-2·h^-1 for continuous aeration and 0.1-0.2 m³·m^-2·h^-1 for intermittent aeration. NIPS membranes with homogeneous structures were less prone to fouling under intermittent aeration, while TIPS membranes with a heterogeneous structure exhibited better recovery under continuous aeration, reflecting distinct fouling dynamics. Findings indicate that the FST alone does not fully represent operational conditions, as aeration efficiency is linked to membrane structure and aeration mode. By combining the FST with ASTs, our approach enables tailored fouling control strategies, reducing energy consumption and improving MBR performance. These insights are critical for advancing toward energy-efficient wastewater treatment technologies.