To balance the high phosphorus concentration in recirculated solution and the stability of biofilm system, this study explored the performance and mechanism of phosphorus uptake/release for recovering phosphorus from sewage when the phosphorus content in biofilm (P_biofilm) changed. The results showed that the maximum phosphorus concentration in the concentrated solution reached 171.2 ± 2.5 mg·L⁻¹ in harvest 1st-5th stages. Polyphosphate accumulating organisms (PAOs) performed a metabolic shift from glycogen accumulation metabolism (GAM) to polyphosphate accumulation metabolism (PAM) when P_biofilm increased at each phosphorus enrichment stage, and more phosphorus was absorbed/released by PAOs. Nevertheless, the release of poly-phosphate from PAOs was inhibited after phosphorus concentration stabilized, and PAOs were unable to absorb phosphorus from wastewater as it reached the phosphorus saturation stage. To maintain the stability of the system, phosphorus had to be harvested so that the saturated phosphorus in PAOs was easily released in a new recirculated solution, resulting in adequate storage space for PAOs to absorb phosphorus. Meanwhile, the ³¹P NMR analysis demonstrated that phosphorus was stored in EPS and cell of PAOs, whereas EPS played a significant role than cell at the anaerobic phase. Particularly, ortho-phosphate was the major component of phosphorus release by EPS and poly-phosphate was the major part of phosphorus release by cell. Furthermore, the change of P_biofilm had no impact on biofilm characteristics and microbial communities, whereas some PAOs would be enriched, and others that were not suitable for this process would be inhibited with repeated cycles of alternating aerobic/anaerobic operation.

_{为平衡再循环溶液中高磷浓度和生物膜系统的稳定性，本研究探讨了生物膜(P biofilm} )中磷含量变化时污水中磷的吸收/释放性能和机制。结果表明，1～5收获期浓缩液中磷的最大浓度达到171.2±2.5 mg·L ^-1。_{当 P生物膜}时，聚磷酸盐积累生物 (PAOs) 进行了从糖原积累代谢 (GAM) 到聚磷酸盐积累代谢 (PAM) 的代谢转变磷在每个富集阶段增加，更多的磷被 PAOs 吸收/释放。然而，在磷浓度稳定后，PAOs中多聚磷酸盐的释放受到抑制，并且PAOs在达到磷饱和阶段时无法吸收废水中的磷。为了维持系统的稳定性，必须收集磷，以便 PAOs 中的饱和磷很容易在新的再循环溶液中释放，从而为 PAOs 吸收磷提供足够的存储空间。与此同时，³¹P NMR分析表明磷储存在EPS和PAOs的细胞中，而EPS在厌氧阶段比细胞发挥重要作用。其中，正磷酸盐是EPS释放磷的主要成分，聚磷酸盐是细胞释放磷的主要成分。此外，P_生物膜的变化对生物膜特性和微生物群落没有影响，而一些PAOs会被富集，而其他不适合这一过程的PAOs会通过反复循环好氧/厌氧操作而受到抑制。