Removal pathways of benzofluoranthene in a constructed wetland amended with metallic ions embedded carbon.

The limited adsorption capacity of the substrate and the concentration of dissolved oxygen in constructed wetlands (CWs) have inhibited their ability to efficiently remove polycyclic aromatic hydrocarbons (PAHs) from wastewater. Presently, biochar and activated carbon modified with Fe and Mn were used as effective sorbents in the removal of benzofluoranthene (BbFA), a typical PAH, in CW microcosms. The addition of metallic ions embedded carbon increased NO-N accumulation by the reduction of Fe and Mn, which led to improved BbFA degradation. Additionally, plant adsorption in root and stem sections were observed separately. The abundance of PAH-degrading microbes in the rhizosphere substrate was higher with the metallic ions embedded carbon than control group. The Fe, Mn and NO-N served as electron acceptors increased BbFA microbial degradation. The removal pathways of BbFA in the modified CWs were proposed which involved settlement in the substrate, plant absorption, and microbial degradation.