Use of constructed wetlands in Latin America: Assessment of current status, opportunities and challenges in Mexico, Chile and Argentina

This study comprehensively analyzes the development, implementation, and challenges of constructed wetlands (CWs) for wastewater treatment (WWT) in Latin America, with a specific focus on Mexico, Chile, and Argentina. A literature review (2000-2024) combined with a review of full-scale implementations reveals distinct national trajectories shaped by climatic, socioeconomic, and regulatory contexts. In Mexico, more than 230 full-scale CWs have been established, predominantly horizontal subsurface flow (HSSF) systems using gravel and tezontle. These are often integrated with ornamental plants to enhance pollutant removal and generate economic value. Chile, driven by water scarcity and supported by greywater reuse regulations, has diversified its configurations to include vertical flow, recirculation, combined vermifilters, and floating wetlands. Domestic wastewater reuse, however, remains unregulated. In Argentina, applications focus on industrial effluents, with free water surface (FWS) and hybrid systems achieving high efficiencies in the removal of heavy metals and nutrients. In all three countries, CWs have demonstrated a high removal efficiency for organic matter, nutrients, faecal coliforms, heavy metals, and emerging contaminants like pharmaceuticals, pesticides, and microplastics. However, their contribution to total WWT remains low. To increase the use of CWs in Latin America and the Caribbean (LAC), numerous challenges must be overcome. Among them is the perception of CWs as an unknown technology by stakeholders. These findings highlight the need for better dissemination of CWs as a reliable technology, as well as the necessity for regional cooperation, the development of design guidelines in Spanish, and greater coordination among academia, the productive sector, and governments.