Emerging impacts of steroids and antibiotics on the environment and their remediation using constructed wetlands: A critical review

The presence of antibiotics and steroids in aquatic environment has the potential to adversely affect the entire ecosystem and human health. The inability of conventional wastewater treatment processes to completely remove these micropollutants further substantiates the need to find alternative cost-effective and eco-friendly treatment processes that can effectively remove them. In this context, a thorough literature survey on the occurrence of antibiotics and steroids in aquatic environment and their remediation methods has been carried out. Amongst, constructed wetlands (CWs) were found to be an effective decentralized sustainable alternative technique. However, the proper understanding of the removal mechanism, such as biodegradation, substrate adsorption, and uptake by macrophytes, is essential for the effective removal of such recalcitrant compounds. Moreover, design and operating conditions of the CWs also influence the removal performance. Hence, different design processes and removal mechanisms under different operating conditions have been discussed in this re-view. Special emphasis on macrophyte types, microorganisms, and substrate variations has been provided to identify the ideal conditions. Performance of CWs is further influenced by substrate surface area, wastewater characteristics, and physicochemical properties of the contaminants. It has been observed that zeolite, activated carbon, Ca-based substrate, bamboo charcoal, and palm mulch have significant potential to remove different contaminants. The interactions between contaminants and operational problems related to the substrate in CWs have also been addressed along with its remediation techniques. This work provides an overview on the removal of antibiotics and steroids from wastewater using CWs and proposes solutions to overcome various inherent problems.

Automated summary

The presence and removal methods of antibiotics and steroids in aquatic environment have been investigated. Constructed wetlands (CWs) were found to be an effective decentralized sustainable alternative. Understanding the removal mechanism and substrate type is important, and the performance of CWs is influenced by substrate surface area, wastewater characteristics, and physicochemical properties of the contaminants.