Reduction in Nutrients, Fecal Coliform Bacteria, and Antibiotic Concentration in a Constructed Wetland

Constructed wetland has evolved into an effective treatment method of effluent, an important consideration in mitigating the escalating problem of antibiotic resistance in environmental and human health contexts. This study evaluated the performance of a 21-acre horizontal flow constructed wetland (HFCW) located at the Nicholls State University Farm for reducing nutrients, fecal coliform bacteria, and antibiotics, in water originating from Bayou Folse receiving treated sewage wastewater. Water samples were collected monthly in triplicate from input and output sites from January 2025 to February 2026. Water quality parameters, such as nitrate, phosphate, ammonia, sulfate, COD and antibiotic concentrations and fecal coliform abundance were analyzed to evaluate treatment efficiency. Significant reductions in sulfate (99.2%) and phosphate (40%) concentrations were observed, along with reduction in other nutrients, between input and output sites over the 14-month study period, indicating nutrient attenuation within the wetland. Antibiotic analysis revealed significant decreases in amoxicillin (81.81%), erythromycin (62.96%), sulfamethoxazole (62.02%), trimethoprim (68.72%), bacitracin (69.77%), tetracycline (69.94%), and penicillin (88.14%) concentrations. Fecal coliform bacterial numbers decreased from input to output site with 32.77% reduction. Overall, the results demonstrated that the constructed wetland effectively reduced nutrients, antibiotics concentration, and fecal coliforms. This study highlights the potential of HFCWs as sustainable mitigation tools for improving water quality.