Wastewater Treatment Using Constructed Wetlands as a Natural Based Solution

Constructed wetlands (CWs) have been developed as an environmentally friendly, cost-effective, sustainable, and ecologically sound alternative to conventional wastewater treatment. This chapter covers the principles/basics of CWs, classifications and types of CW systems, and operational mechanisms for removing nutrients, organic matter, heavy metals, and pathogens. It also explores potential applications, including municipal, industrial, and agricultural wastewater treatment, while highlighting key obstacles and constraints. We addressed major challenges that could be a guide for future research directions, including land footprint requirements, media clogging, and climate variability. The efficiency of CWs in removing various pollutants has been extensively studied, with elimination mechanisms including microbial degradation, substrate adsorption, sedimentation, and phytoremediation for organics, pathogens, heavy metals, and nutrients. CWs offer significant advantages, including low energy consumption, adaptability to decentralized settings, operational simplicity, and biodiversity enhancement, provided that design appropriateness, climate conditions, and other parameters are considered. This chapter provides comprehensive insights into CWs to address global water scarcity and pollution challenges. CWs require sustainable and optimized designs, along with integration into circular economy principles, to enhance their long-term viability. This chapter aims to serve as a comprehensive resource for researchers seeking nature-based solutions for wastewater treatment in alignment with the Sustainable Development Goals (SDGs).