This book provides a comprehensive exploration of the role of constructed wetlands in sustainable wastewater treatment and their contribution to the emerging concept of the biocircular economy. The book is divided into three parts. Part I covers the fundamentals, basic design, efficiency, maintenance, limitations, performance assessment, and sustainability of constructed wetlands. It also provides an overview of the current situation. Part II is dedicated to recent advancements and novel applications of constructed wetlands for wastewater treatment, including various emerging technologies, bioelectrochemical systems. The last part concludes with a global scenario, challenges, life cycle assessment, and techno-economical analyses of constructed wetlands. It also provides the information on the techniques and methodologies that facilitate the integration of wastewater treatment technologies; the bibliometric overview of the research progress and challenges; policy landscape; global perspectives; and green circular economy. The book is a valuable resource for researchers, practitioners, and policymakers interested in advanced sustainable wastewater treatment solutions.