Simultaneous phosphorus recovery from wastewater and sludge by a novel denitrifying phosphorus removal system

•Increased nitrate concentration facilitated the activity of denitrifying P removal.•Increased nitrate concentration stimulated the process of C, N, and P metabolism.•The maximum P concentration reached 172.5 ± 3.5 mg/L in enriched stream.•EPS release was the primary pathway for P release in acid/alkaline fermentation.•Pure struvite crystals were obtained from the enriched stream and supernatant.