Carbon slow-release and enhanced nitrogen removal performance of plant residue-based composite filler and ecological mechanisms in constructed wetland application

Continuous and stable carbon release and coupled microbial efficacy of external carbon source solid fillers are the keys to enhanced nitrogen removal in constructed wetlands. The constructed wetland plant residue Acorus calamus was cross-linked with PHBV to create composite solid carbon source fillers The relatively high abundances of nap, narG, nirKS, norB, qnorZ and nosZ, guaranteed efficient denitrification performance in Ac-BDPs constructed wetlands. Our study introduces a reliable technique for biological nitrogen removal by using the composite carbon source filler in constructed wetlands with insufficient carbon source.