Evaluating iron scraps for improved sulfur autotrophic denitrification and phosphorus removal in subsurface flow constructed wetlands
Azharuddin Chachar, Shanshan Sun, Yuanyuan Peng, Xushun Gu, Naven Ramdat, Tongtong Ren, Shengbing He
Abstract
The increasing stringency of nitrogen (N) and phosphorus (P) discharge standards necessitates more effective and eco-friendly wastewater treatment technologies. This study evaluated the performance and microbial community dynamics of elemental sulfur (S 0 )-based sulfur autotrophic denitrification (SAD) enhanced by iron scraps (ISs) in subsurface flow constructed wetlands (SSF CWs) under low and high temperatures. Three experimental setups were tested: control (C-SSF), S 0 -added SSF CW (S-SSF), and combined ISs and S 0 -added SSF CW (Fe + S-SSF). Results showed that ISs addition in SAD significantly improved total nitrogen (TN) and total phosphorus (TP) removal efficiencies, achieving maximum TN and TP removal of 77.14 % and 87.11 %, respectively, in Fe + S-SSF. Microbial analysis revealed enrichment of key denitrifying genera, particularly Ferritrophicum , across both temperature conditions, enhancing N and P removal. ISs also promoted functional gene enrichment associated with denitrification processes, further supporting improved nutrient removal. This study highlights ISs as a sustainable enhancement for SAD in advanced wastewater treatment.