Fulvic acid impact on constructed wetland–microbial electrolysis cell system performance: Metagenomic insights

This study explores the roles of fulvic acid (FA) in both a conventionally constructed wetland (CCW) and a newly constructed wetland – microbial electrolysis cell (ECW). The results showed that FA increased the average removal efficiency of chemical oxygen demand, total phosphorus, total nitrogen, and ammonia nitrogen in ECW by 8.6, 46.2, 33.0, and 27.9 %, respectively, compared to CCW, and reduced the global warming potential by > 60 %. FA promoted the proliferation of electroactive bacteria (e.g., Chlorobaculum and Candidatus Tenderia ) and FA-degrading bacteria (e.g., Anaerolineaceae and Gammaproteobacteria) and reduced methanogens (e.g., Methanothrix ) via type-changing. The study’s findings suggest that FA influences pollutant removal and microbiome dynamics by altering dissolved oxygen levels and redox potential. In summary, FA and ECW enhanced the efficiency of constructed wetlands by facilitating electron transfer and consumption, and supporting microbial growth and metabolism.