Multiscale mechanisms of clogging mitigation and nitrogen removal enhancement in constructed wetlands by alternating...

While constructed wetlands offer an ecologically sustainable and low-energy alternative for wastewater treatment with considerable application potential, their implementation presents distinct challenges and operational limitations. This study pioneers the novel integration of a low-voltage alternating current electric field with CWs (ACCW) to simultaneously overcome the persistent challenges of clogging and limited total nitrogen removal. Unlike conventional bioelectrochemical approaches, this novel strategy simultaneously targets clogging mitigation and enhances microbial metabolic functions essential for nitrogen removal through multi-scale interventions. Physically, it reduced particle size of clogging substances and modified the properties of substrates. Chemically, it decreased key extracellular polymeric substance components, including polysaccharides (75.24 %), proteins (6.18 %), and humic acids (12.80 %), while simultaneously modifying the functional groups of organic constituents. Biologically, it regulated microbial community structure, and modulated the expression intensity of key metabolic pathways. Notably, the alternating current electric field improved total nitrogen removal by stimulating adenosine triphosphate production, enriching denitrifying bacteria, upregulating key nitrogen metabolic pathways, and enhancing the transport of nitrogen-processing components like molybdate and essential amino acids. This work provides fundamental insights into the bioelectrochemical mechanisms underlying simultaneous clogging mitigation and enhanced denitrification in ACCW, establishing this technology as a sustainable and efficient solution for advanced wastewater treatment.