• • Effluent NH4+-N and TN averaged (5±3.4) mg·L−1 and (10±2.8) mg·L−1, respectively, with COD at (30±6.2) mg·L−1 under HRT 10 h, self-circulation 29–58 times, and upflow velocity 11–18 m·h−1, meeting stringent discharge standards.
• • Sludge concentration increased from 5,080 to 6,650 mg·L−1, with mean particle size 209.6 μm and SVI 50–60 mL·g−1, indicating excellent settleability and biomass accumulation critical for continuous-flow operation.
• • EPS content rose from 26.05 to 68.27 mg·g−1, with PN increasing from 21.26 to 59.44 mg·g−1 and PS from 4.79 to 8.82 mg·g−1, raising PN/PS from 4.4 to 6.7, which enhances granule structural integrity and stability.
• • The self-circulation driven by aeration (29–58 times) provides hydraulic shear forces essential for AGS formation and maintenance, eliminating the need for mechanical mixing or sludge return pumps, thereby reducing energy consumption and operational complexity.