Plant biomass production in large-scale constructed wetlands under tropical climate conditions

This study focused on plant biomass production in a large-scale Constructed Wetland (CW) system integrating vertical subsurface flow (VSSF), horizontal subsurface flow (HSSF), and surface flow (SF) wetland units, located in Nautla, Veracruz, Mexico. Given the nature of the study, 13 ornamental plant species were utilized. Over a 12-month monitoring period, plant growth parameters, biomass yield, and pollutant removal efficiency were assessed . Cyperus papyrus demonstrated the most vigorous performance, reaching a height of up to 244.36 cm within the first six months and accumulating an aboveground biomass increase of 3864.85 %. Colocasia esculenta and Sansevieria trifasciata also showed substantial biomass gains, maintaining balanced development in both aerial and root systems. A total biomass of 883.70 kg was recorded across all species by the end of the study. Average pollutant removal efficiencies across the system were 93.37 % for Chemical Oxygen Demand (COD), 91.37 % for Total Nitrogen (TN), and 91.45 % for Total Phosphorus (TP). A positive correlation ( r = 0.5460) was found between total biomass and contaminant removal, suggesting that increased plant productivity enhances treatment performance. In addition to vertical growth, species displayed variation in stem thickness, flowering cycles, and leaf production. Notably, Pontederia cordata and Heliconia psittacorum contributed to biodiversity and pollinator support. The findings suggest that the strategic selection and combination of plant species can improve the functional performance of large-scale CWs across different operational stages, increasing system resilience to variable pollutant loads and promoting long-term treatment sustainability. • Constructed wetland assessed with 13 ornamental plant species. • Cyperus papyrus reached 244.36 cm and showed the highest biomass yield. • Plant diversity improved biomass production and pollutant removal. • Biomass growth correlated with COD, TN, and TP removal efficiency. • Species with different cycles enhance wetland resilience and function.