Constructed Wetlands as a Solution for Sustainable Sanitation: A Comprehensive Review on Integrating Climate Change Resilience and Circular Economy.

About eighty percent of wastewater is discharged into the environment untreated. Many challenges are decelerating solving the global sanitation problem, such as the financial limitations and lack of technical capacities. Parallel to this, many countries are facing a growing demand on their limited water resources. Higher water demand and limited availability leads to over-abstraction and deterioration in the availability and quality water resources. In this situation, wastewater can be a new water source. Therefore, there is a growing interest in finding low-cost, easy-to-operate and sustainable sanitation solutions. Constructed wetlands (CWs) in recent years have proved their capability in the sanitation sector as an appropriate sanitation system in different contexts, CWs have proved their ability to treat several types of wastewaters for several decades. Several benefits and facts, such as the low construction and operational costs of CWs, low-energy, and less operational requirements, have raised the interests in CWs as a treatment technology. Several studies have investigated CWs suitability based on different sustainability indices (technical, social, environmental, etc.). In this paper, a comprehensive review covers the definition, types, treatment processes, sustainability criteria, limitations, and challenges of CWs. The paper also focuses on climate change resilience and circular economic approach under the technical and financial criteria, respectively. [ABSTRACT FROM AUTHOR]