This study explored the influence of ferrous iron (Fe²⁺) addition on ammonium nitrogen (NH₄-N) removal and microbial communities in horizontal subsurface flow constructed wetlands (HSSFs) at different carbon/nitrogen (C/N) ratios. Fe²⁺ addition could improve NH₄-N removal under the C/N ratio of 2.1 and alter the microbial community structure. The microbial diversity and functional genes at the C/N ratio of 2.1 were enhanced by the addition of 50 mg/L Fe²⁺, with the increases observed in NH₄-N and total nitrogen (TN) removal. This indicates the enhancement of nitrogen removal by Fe²⁺ addition with the presence of high organic matter. However, the enhancement of Fe²⁺ on chemical oxygen demand removal was not obvious overall. The relative abundance of functional genes and those related to energy metabolism, xenobiotic biodegradation, and metabolism decreased significantly in HSSFs with Fe²⁺ at C/N ratio of 1.1, whereas they increased in HSSFs with the addition of 50 mg/L Fe²⁺ at C/N ratio of 2.1.

这项研究探讨了在不同碳/氮（C / N）比下，水平地下地下人工湿地（HSSFs）中亚铁（Fe ²⁺）的添加对铵态氮（NH ₄ -N）去除和微生物群落的影响。在2.1的C / N比下，添加Fe ²⁺可以改善NH ₄ -N的去除，并改变微生物群落结构。通过添加50 mg / L Fe ²⁺可以提高C / N比为2.1时的微生物多样性和功能基因，并观察到NH ₄ -N和总氮（TN）的去除增加。这表明Fe ²⁺对氮的去除作用增强另外还有高有机物的存在。然而，Fe ²⁺对化学需氧量去除的增强作用总体上并不明显。Fe ^2+的HSSF中功能基因以及与能量代谢，异源生物降解和代谢相关的基因相对丰度以1.1的C / N比显着降低，而添加50 mg / L Fe ^2+的HSSF中功能基因的相对丰度显着增加。C / N比为2.1。