Antibiotics and microbial resistance genes removal in constructed wetlands

The aims of this literature review were to assess the potential of constructed wetlands (CWs) to remove antibiotics as β-lactams, macrolides, fluoroquinolones, sulfonamides, and tetracyclines, to determine the main mechanisms responsible for their removal, and to assess the potential of CWs to remove selected antibiotic resistance genes (ARGs). The results of this review suggest that vertical-flow CWs are more efficient at removing both antibiotics and ARGs than horizontal-flow CWs. Aerobic biodegradation and adsorption were identified as the dominant processes responsible for antibiotic removal. These processes can be enhanced by increasing oxygen transfer and supplementing the substrate (i.e. filtration bed) with specific sorbents. The primary mechanisms of ARGs removal have not been clearly identified, but it can be hypothesized that ARGs elimination may be mediated by multiple factors that can produce a synergistic effect in CWs, although this is related to the conditions prevailing in CWs. This literature review has shown that there is a need for further expansion of knowledge in this area, especially in the context of a better understanding of the mechanisms involved in the removal of ARGs in CWs.