Mixotrophic denitrification with Arundo donax straw and elemental sulfur in constructed wetlands: enhanced nitrogen removal, carbon-sulfur interactions, and greenhouse gas mitigation.

Mixotrophic surface flow constructed wetlands with Arundo donax straw and elemental sulfur achieve 794.45 mg N/(m²·d) nitrogen removal, surpassing traditional systems by over 24% and 213%, respectively.

• Why it matters: Efficient nitrogen removal in low carbon-to-nitrogen wastewater treatment is limited by insufficient electron donors, leading to poor denitrification and increased greenhouse gases, posing environmental challenges.
• What they did: The study integrated Arundo donax straw and elemental sulfur into wetlands over 160 days, employing metagenomics and metabolomics to analyze microbial communities and metabolic pathways involved in nitrogen, sulfur, and carbon cycling.
• The result: Enhanced microbial activity and sulfur transformation pathways reduced greenhouse gas potential by 24.75%, enabling more sustainable wetland designs that improve nitrogen removal while mitigating climate impact.