Pilot-scale aerobic granular sludge treating domestic wastewater under tropical climate conditions: Different feeding strategies on granules formation

·day; COD: 195.6 ± 57.8 mg/L; C/N 9:1 C/N 9:1) at a pilot scale was investigated. Two sequencing batch reactors (SBRs) were started up with no inoculum and operated with different cycle configurations. SBR1 operated on a 4-h cycle with a 40-min non-aerated phase followed by 180 min of aeration, while SBR2 had a 15-min non-aerated phase followed by 205 min of aeration, treating real sewage to determine how feeding phase duration influences granulation, EPS dynamics, and nutrient removal under high-temperature and low-strength conditions. AGS formation occurred within 80 and 48 days in SBR1 and SBR2, respectively. Both reactors achieved COD and ammonia removal rates of over 70% and 80%, respectively. SBR1 showed superior COD removal (83 ± 8% vs 74 ± 15%) due to higher biomass retention, while SBR2 exhibited faster granulation and higher average EPS (203 ± 109 vs 157 ± 137 mg/g VSS). Nitrite accumulation in SBR1 (8.2 ± 5.3 mg/L) reflected free ammonia inhibition of NOB, whereas SBR2 produced more nitrate (4.4 ± 4.2 mg/L). EPS declined sharply to 33-49 mg/g VSS under low F/M ratios (