A review on constructed wetlands-based removal of pharmaceutical contaminants derived from non-point source pollution

Abstract

In the current decade, Non-Point Source (NPS) pollution has become a critical global problem in both developing and developed countries. As a result of diverse human activities, NPS pollution has led to an excessive supply of inorganic nutrients (e.g., phosphorus, nitrogen, and metals) and organic compounds (e.g., pharmaceutical compounds and pesticides) into soils and surface waters which change the water quality. Continuous discharge of pollutants by NPS source mainly affects the soil and aquatic ecosystem, damaging the food chain and food web that exist in this Earth planet. On such a serious note, methods to mitigate the pollutants derived from NPS sources or treatment methods could effectively reduce the contaminant load. Recently, the use of constructed wetlands (CWs) for bioremediation purposes has been gaining considerable attention in many countries since they mostly mimic the natural and eco-friendly process for mitigating various types of pollutants. Although their successful use in the treatment of point source pollutants is well documented, information on the performance of CWs for treating organic pollutants, particularly pharmaceutical residues, is still not adequately summarized. Therefore, this paper focuses on outlining and reviewing the current information related to the use of CWs in mitigating pharmaceutical contaminants (PCs) in soil and water reservoirs. Firstly, we summarized the key aspects on sources, occurrence, fate, and ecotoxicological effects of most common pharmaceuticals derived by NPS pollution. The second objective deals with the significance of plants present in CWs that help PCs remove via various possible mechanisms. Thirdly, we discuss the roles and importance of other factors (e.g., microorganism, temperature, and substrate) to remove PCs efficiently. Overall, this review highlights the current state-of-art of CWs for mitigating NPS-derived PCs and presses the area where future research is required to make the CWs application more successful shortly.