Antibiotics and antibiotic resistance genes from wastewater treated in constructed wetlands

With the development of technology, two new pollutants, antibiotics as well as antibiotic resistance genes (ARGs), have become global environmental and health problems. Various antibiotics and ARGs have been extensively detected in sewage. Compared with traditional wastewater treatment plants, constructed wetlands (CWs) show the following advantages: low energy consumption and low operation and management costs as well as being very efficient at removing antibiotics and ARGs. This study reviewed the factors affecting the efficiency of CWs in their elimination of antibiotics and ARGs from wastewater. Overall, the vertical-flow subsurface CWs showed the highest removal efficiencies for antibiotics (>60%). In addition, CWs with plants and substrate materials such as zeolite and brick pellets were highly efficient at removing antibiotics (73%-99.15%). Up-flow subsurface CWs were better at removing ARGs (63.76% to 96.83%). In addition, the presence of plants promoted the elimination of ARGs from wastewater in CWs. Moreover, microorganisms in CWs have a great impact on the removal of ARGs, that CWs remove ARGs from wastewater by directly ieliminating microorganisms. However, further research is necessary to further understand the mechanisms of the elimination of antibiotics and ARGs from wastewater within CWs.