Performance and Membrane Fouling of a Novel Algal-Bacterial Aerobic Granular Sludge (Abgs)–Membrane Bioreactor for Municipal Wastewater Reuse: Effect of Abgs Size

Abstract

A novel algal bacterial aerobic granular sludge (ABGS)–membrane bioreactor (MBR) for wastewater reuse was established to improve the pollutants removal and mitigate membrane fouling. Six ABGS particle sizes (< 0.60, 0.60-0.85, 0.85-1.18, 1.18-1.70, 1.70-2.00, and > 2.00 mm) were adopted to investigate their influence on the ABGS-MBR system. An optimal size (0.85-1.18 mm) was identified, which had the longest operation time (141 days) and the lowest fouling resistance (6.41 × 10 11 m -1 ). This was possibly due to that it formed a loose cake layer and produced the content of lowest extracellular polymeric substances (EPS). For ABGS particles < 0.85 mm, the small granules and flocculent sludge formed a dense fouling layer on the membrane surface, which quickly increased the fouling resistances. ABGS particles > 1.18 mm secreted more EPS and formed more disintegration products of ABGS, which could enter the membrane pores through the loose cake layer, thereby causing severe membrane pore blocking. Moreover, the thermodynamic and microscopic analyses showed that the minimum membrane fouling occurred at an ABGS particle size of 0.85-1.18 mm. This study elucidates the influence of ABGS particle size on membrane fouling mechanisms and provides a novel strategy to mitigate membrane fouling.

Keywords: membrane fouling, Algal-bacterial aerobic granular sludge, Particle size, Extracellular polymeric substance, XDLVO theory