• Hierarchic micro-environments structured distinct nitrogen and phosphorus removal zones. • Temperature shifts altered dominant N/P metabolic pathways across micro-environmental levels. • Higher temperature favored DPR, reducing reliance on conventional denitrification. • Microbial succession and functional genes jointly governed temperature-dependent N/P removal. Temperature fluctuations pose a critical challenge to stable nitrogen and phosphorus removal in wastewater treatment, whereas hierarchical microenvironments enable multipath microbial metabolism, thereby ensuring process resilience. This study aimed to elucidate multi‑path metabolic characteristics of N/P and their temperature‑response mechanisms based on hierarchic micro-environments in full-scale Bardenpho process, integrating year‑round water quality monitoring, sludge activity assays, and metagenomic analysis. The results revealed distinct functional zones for N and P removal within hierarchical micro-environments. Temperature exhibited differential effects on the rates of various N and P metabolic processes. When the temperature was 28 °C, the core anoxic zone accounted for 40.8% of total nitrogen removal, while TP removal reached 8.7 mg/L, representing up to a 5.5-fold increase relative to 15°C, indicating a transition in the dominant metabolic pathway from conventional heterotrophic denitrification toward denitrifying phosphorus removal. Microbial analysis further indicated that the denitrifier Rurivivax was enriched at lower temperatures, whereas the polyphosphate‑accumulating organism Candidatus Accumulibacter reached its highest abundance at 24 °C. Quantitative analysis of functional genes revealed a temperature-driven shift from narG / nirK toward napA / nirS , along with coordinated reallocation of carbon between storage and utilization pathways. This study elucidates the temperature‑response patterns of multi‑level micro‑environments from the perspectives of process performance and microbial succession, providing a theoretical basis for targeted process regulation under varying temperature conditions.
Zhang et al. (Sun,) studied this question.