Performance of Large-Scale Ornamental Wetlands for Municipal Wastewater Treatment: A Case Study in a Polluted Estuary in the Gulf of Mexico

This study investigates the performance of large-scale ornamental treatment wetlands (TW) for the treatment of municipal wastewater in the municipality of Nautla, Veracruz, Mexico, specifically within a contaminated estuary in the Gulf of Mexico. The research employed a treatment wetland system that integrates mixed flow methods, including vertical subsurface flow (VSSF) and horizontal subsurface flow (HSSF), to optimize operational, maintenance, and energy costs. Over a monitoring period from 15 October 2022 to 17 September 2023, the system achieved remarkable efficiencies in the removal of chemical oxygen demand (COD), NH3-N, NH4-N, NO2-N, NO3-N, total nitrogen (TN), with removal rates of 93.37%, 93.37%,91.36%, 91.29%, 95.74%, 97.36%, 71.69%, 92.26% and 91.45%, respectively. The effluent complied with the water quality standards established by the official Mexican standard NOM-001-SEMARNAT-2021, demonstrating the effectiveness of this TW configuration in treating water characterized by high chemical oxygen demand, nitrogen, and phosphorus levels. The results are especially relevant for tropical climates, where high temperatures and humidity can affect microbial activity and nutrient cycling, potentially enhancing treatment performance and reducing construction and management costs. This research highlights the viability of ornamental treatment wetlands as a sustainable solution for wastewater treatment in tropical climates and provides valuable information for future implementation and design criteria.