The long-term effect of nitrite on the granule-based enhanced biological phosphorus removal system and the reversibility

► Nitrite deteriorated the settleability, stability and integrity of the granules. ► Nitrite could inhibit the excretion of polysaccharides. ► Granules with lower proteins/polysaccharides had better structure and function. ► The community composition was not reversible by recovery. ► GAOs had stronger resistibility and higher recovery rate than PAOs.