Evaluation of the Efficiency of a Subsurface Flow Wetland in Contaminant Removal: Results on the Impact of Hydraulic Retention Time

Abstract

Abstract – This study provides valuable insights into the behavior and performance of a subsurface flow wetland, offering a solid foundation for optimizing the design and operation of similar systems for environmentally sustainable wastewater treatment. The system's efficiency in removing various contaminants was evaluated, considering different hydraulic retention times (HRT) ranging from 3 to 15 days. A total of 24 water samples were collected for analysis. The evaluated parameters included total and fecal coliforms, hydrogen potential (pH), turbidity, color, dissolved oxygen, suspended solids, temperature, chemical oxygen demand (COD), and biochemical oxygen demand (BOD5). Additionally, nutrients such as total nitrogen, ammonia nitrogen, nitrate nitrogen, total phosphorus, and orthophosphates were analyzed. The results provide an understanding of the HRT's impact on effluent quality improvement and help identify the optimal retention time to maximize treatment efficiency in this type of system. Keywords – subsurface flow wetland, wastewater treatment, hydraulic retention time (HRT), contaminant removal, effluent quality.