Application of Biofilm Modeling and Dynamic Aeration Control for Optimization of Pilot Scale Granular Sludge SBR Treating Slaughterhouse Wastewater

The present study evaluated the performance of a 330 L on-site pilot-scale aerobic granular sludge sequencing batch reactor (AGS-SBR) in removing COD, total nitrogen (TN), and phosphorus (PO43−–P) from slaughterhouse wastewater. The effectiveness of a novel two-step dynamic aeration control scheme for optimizing SBR operation was also analyzed. Initially, a start-up phase (Days 1–60) using hydraulic and microbial selection pressure was implemented to convert flocculant seed sludge into granular sludge, followed by long-term operation in three stages. In Stage I (Day 61–216), operated under a 12-h anaerobic/aerobic/anoxic cycle with static aeration, removal efficiencies of 91% for COD, 66% for TN, and 70% for PO43−–P were achieved. Cycle profiling confirmed the establishment of the anaerobic feast–aerobic famine regime essential for granulation. In Stage II (Day 217–330), a DO-based dynamic aeration strategy based on SumoBioFilm® simulations was implemented. Maintaining DO at 3–4 mg/L increased the degree of simultaneous nitrification-denitrification from 56% to 73%, improved TN and PO43−–P removal to 78% and 75%, and reduced aeration time by 15%. Stage III (Day 331–448) introduced ammonium-threshold-based control (NH4+–N≤4 mg/L), further optimizing aeration duration and enhancing anoxic denitrification from 17% to 33%. This increased TN and PO43−–P removal to 84% and 78%, while reducing average aeration time by 26%. Microbial analysis of sludge from Stage I (Day 196) and Stage III (Day 412) of the pilot AGS-SBR revealed significant community shifts driven by adaptive aeration control. Stage III sludge showed dominance of Proteobacteria (69.98%) and higher abundances of key nitrifiers (Nitrosomonas, Nitrobacter) and denitrifiers (Pseudomonas, Thauera), correlating with improved nutrient removal. The presence of Burkholderia and Nocardioides further supported enhanced performance. In contrast, Stage I sludge had lower levels of these functional groups. Overall, the results demonstrate AGS-SBR viability for high-strength wastewater and emphasize the importance of microbial monitoring and dynamic control for optimal treatment.