Iron phosphate (Fe-P), the active compound is part of the main storage paths of phosphorus, especially in P-pollution environment. The re-release of Fe-P is a danger sign during microalgae remediation. In this work, pre-incubated Chlorella vulgaris is cultured in BG-11 culture medium with different amounts of quantifying Fe-P. The effects of Fe-P re-release on biomass, flocculation and removal of PO43- are investigated. The results indicated that Chlorella vulgaris can promote the dissolution and release of Fe-P when the pH is 7, the release amount of Fe-P (Q) in 200mL water reaches 0.055-0.45mg d-1 under the Chlorella vulgaris concentration of 5.6×105-8×105cell mL-1. Meanwhile, the growth of Chlorella vulgaris will be inhibited due to flocculation behavior of Fe3+ in the release stage, this goes hand in hand with the specific growth rate of 0.3-0.4d-1 and below 30% phosphorus removal rate. However, this process in the long run means a favorable transformation that Fe-P becomes a bioavailable phosphorus as a resource under the action of Chlorella vulgaris. Microalgae outbreaks may also be triggered by persistent interactions between Fe-P and Chlorella vulgaris. The study provides an important reference for the application of Chlorella vulgaris in a Fe-P rich environment.

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