This study evaluated the performance of a pilot-scale constructed wetland system planted with Heliconia psittacorum for the treatment of domestic effluent at the Cohab Nova Wastewater Treatment Plant in Cáceres, Mato Grosso, Brazil. Statistical analysis indicated stability in pH levels between the system’s influent and effluent (7.08 and 7.12, respectively; p > 0.05), suggesting maintenance of acid-base balance. A significant, albeit modest, increase in dissolved oxygen (DO) was observed, indicating slight oxygenation along the wetland flow path (p < 0.05). The system exhibited statistically significant efficiency in the removal of total dissolved solids (TDS), turbidity, and nitrite, with average reductions of 14.9%, 70%, and 34%, respectively, throughout the monitoring period. Conversely, there was a trend toward increased concentrations of phosphorus and biochemical oxygen demand (BOD) in the effluent, although these were not statistically significant, suggesting possible internal phosphorus release and accumulation of organic matter that may limit the system’s capacity for these parameters.

Simple linear regression models demonstrated positive functional responses of the system to applied loading rates for most parameters, especially TDS (R²=0.83; p < 0.0001), turbidity (R²=0.67; p < 0.01), BOD (R²=0.58; p < 0.05), and phosphorus (R²=0.35; p < 0.05), indicating no evidence of saturation for these variables under the studied conditions. pH and DO did not show significant correlations with the applied load, reflecting system stability and the influence of external factors, respectively.

The results confirm the potential of constructed wetlands for selective removal of physical, chemical, and biological contaminants in domestic effluents, but also highlight limitations in nutrient and organic matter control, which should be considered when planning complementary strategies and system sizing. From an environmental standpoint, the integration of native vegetation and the use of local materials (sand and gravel) enabled operation with minimal waste generation and low energy consumption, ensuring environmental compatibility and conservation of local water resources. Economically, the system demonstrated low installation and operational costs, favored by the use of local labor and simple construction techniques, making it a financially viable alternative for communities with limited sanitation infrastructure.