Performance and resilience of ONP ‐2‐bioaugmented sequencing batch reactors under nitrogen and phosphorus shock loading

Nitrogen and phosphorus load fluctuations in biological wastewater treatment systems can compromise reactor performance. In this study, sequencing batch reactors were operated under stepwise nitrogen or phosphorus shock loadings to evaluate the effects of bioaugmentation with the ONP‐2 mixed consortium (ONP‐2). Bioaugmentation significantly enhanced reactor resilience and accelerated recovery after shock events. Under nitrogen shock, the bioaugmented reactor maintained removal efficiencies above 96%, 10.93% higher than the control, while mitigating the decline in phosphorus removal, with the high‐loading Phase II Total Phosphorus(TP) removal improving by up to 10.71%. Under phosphorus shock, TP removal efficiency increased by 6.72% compared with the non‐bioaugmented reactor. Mechanistic analysis indicated that ONP‐2 enhanced resistance to nutrient shocks by stimulating N ‐acyl homoserine lactones‐mediated quorum sensing, particularly via C6‐HSL and C8‐HSL, which promoted the enrichment of functional microorganisms and strengthened microbial interactions. These findings demonstrate that bioaugmentation improves the stability of wastewater treatment systems under fluctuating influent conditions and provide new insights into the quorum‐sensing mechanisms underlying enhanced process robustness.