Pilot-scale demonstration of aerobic granular sludge augmentation applied to continuous-flow activated sludge process for the treatment of low-strength municipal wastewater

This study investigated the application of aerobic granular sludge (AGS) augmentation strategy to continuous-flow activated sludge (AS) process (mainstream) for the treatment of low-strength municipal wastewater using a pilot-scale demonstration plant. A sidestream sequencing batch reactor (SBR) was adopted for AGS production, and the AGS produced was supplied to a mainstream reactor. In the sidestream, a simultaneous feeding and drawing SBR was operated. AGS rapidly formed in terms of sludge volume index (SVI) and AGS fraction and stabilized (SVI30: 62 ± 5 mL g−1, AGS fraction: 40–60 %). The installation of a novel SBR cycle, with alternately repeated steps of short and long aeration times, further improved the settleability (SVI30: 47 ± 6 mL g−1) and contributed to an increase in AGS production by ∼50 %. AGS augmentation increased the AGS fraction (20–30 %) in mainstream, and SVI30 improved to