Montmorillonite supported nanoscale zero-valent iron immobilized in sodium alginate (SA/Mt-NZVI) enhanced the nitrogen removal in vertical flow constructed wetlands (VFCWs)

Abstract Lacking of electron donor generally causes the low denitrification performance of constructed wetlands (CWs). Montmorillonite supported nanoscale zero-valent iron immobilized in sodium alginate (SA/Mt-NZVI) as novel electron donor-acceptor compounds were added in the denitrification zone of vertical flow constructed wetlands (VFCWs) to enhance the nitrogen removal. The key factors of the SA/Mt-NZVI dosage, the hydraulic retention time (HRT) of VFCWs, and the C/N ratios of influent were explored. SA/Mt-NZVI significantly improved the nitrogen (NO 3 − -N) removal efficiency in VFCWs. When the optimal dosage of SA/Mt-NZVI was set as 2 g and the C/N was set as 6, the highest NO 3 − -N removal efficiency was improved by 32.5 ± 1.0%. The microbial community analysis of by 16S rRNA had revealed that Proteobacteria and Bacteroidetes at phylum level and Betaproteobacteria , Gammaproteobacteria , and Alphaproteobacteria at class level played an important role in nitrogen removal.