Ecosystem Services Valuation of Constructed Wetland as a Nature-Based Solution to Wastewater Treatment

Constructed wetlands (CWs) are nature-based solutions that utilize natural vegetation, soils, and microbes to treat domestic wastewater and industrial effluents. They are engineered treatment systems that mimic the functions of natural wetlands to capture stormwater, reduce nutrient loads, and create diverse wildlife habitats. Providing these monetary and non-monetary benefits, its implementation has grown in several applications and geographical spread. Recent studies integrate the ecosystem services of CWs in project valuation, and the critical analysis of research hotspots has not been made yet. This study employs a systematic review to analyze the literature on ecosystem services provided by CWs and how they are incorporated into the valuation of CW projects. Among the ecosystem services that have been identified are provisioning (biomass and water supply), regulating (wastewater treatment and purification, climate regulation, flood prevention, and erosion control), cultural (recreation and aesthetic, biodiversity, education, and research), and supporting (habitat formation, nutrient cycling, and hydrological cycle). In terms of valuation methods and techniques, the results identified contingent valuation, shadow pricing, cost–benefit analysis, benefits transfer, habitat evaluation procedures, replacement cost, and travel cost. The analysis results provide researchers with a concrete basis for future studies and directions for further development. This also provides policymakers and CW project planners with valuable insights on various aspects of policy support for CW adoption and project valuation.