Enhanced Benzofluoranthrene Removal in Surface Flow Constructed Wetlands with the Addition of Carbon

Polycyclic aromatic hydrocarbons (PAHs), as hazardous pollutants, could be removed by constructed wetlands (CWs). While the traditional substrate of CWs has a weak adsorption capacity for PAHs, in this study, the carbonous fillers-activated carbon (AC) and biochar-were added into the substrate of surface flow CWs to improve the removal performance of benzofluoranthrene (BbFA), a typical PAH. The results showed that the BbFA removal efficiencies in CWs with the addition of AC and biochar were 11.8 and 1.2% higher than those in the Control group, respectively. Simultaneously, the removal efficiencies of NO₃ ^--N were 42.8 and 68.4% in these two CWs, while the BbFA content in the substrate and plants with the addition of carbon was lower than that in the Control group. The addition of carbonous filler reduced the absorption of PAHs by plants in CWs and enhanced microbial degradation. The microbial community results showed that the relative abundance of Proteobacteria, especially γ-proteobacteria, was higher with the addition of fillers, which related to PAH degradation.