Role of Constructed Wetlands in Wastewater Treatment and Mitigation of Emerging Contaminants

Traditional wastewater treatment methods are not enough in the current scenario due to the emergence of various kinds of pollutants in the environment. Emerging contaminants (ECs), including pharmaceuticals, endocrine-disrupting chemicals, and nanoplastics, pose significant risks to ecosystems and human health due to their persistence and toxicity. New approaches are being developed that concentrate on the simultaneous removal of pollutants like carbon, nitrogen, phosphorus, and ECs. Constructed wetlands (CWs) have proven to be effective, sustainable systems for mitigating these contaminants through integrated physical, chemical, and biological mechanisms. Constructed wetlands offer a cost-effective and sustainable alternative for wastewater treatment, capable of removing organic pollutants, nutrients, and emerging contaminants (ECs) like pharmaceuticals and personal care products. Advanced configurations include vertical subsurface flow systems and aerated CWs. This chapter explores the role of CWs in wastewater treatment, focusing on the mechanisms enabling the removal of ECs, such as pharmaceuticals, endocrine-disrupting pollutants, and microplastics. The chapter emphasizes the importance of physical, chemical, and biological processes, such as sorption, phytoremediation, and microbial biodegradation. Key findings include the influence of hydraulic retention time, aeration rates, and substrate composition on pollutant removal, and the critical role of plant-microbe interactions in degrading ECs. Combining advanced processes with CW systems is also discussed in the chapter, such as adding biochar for enhanced removal efficiency. By synthesizing recent advances, this work provides a roadmap for optimizing CW systems to address emerging contaminants and meet the growing demand for environmentally sustainable wastewater treatment technologies.