title: 15 mg/L Fe(III)
design: This study investigated the long-term effects of gradient Fe(III) exposure (0, 10, 15, 20, 25 mg/L) on denitrifying phosphorus removal (DPR) systems over 120 days. High-throughput 16S rRNA gene sequencing was used to reveal microbial community succession, functional genus dynamics, and metabolic pathway shifts under iron stress.