Performance of a Horizontal Flow Constructed Reed Bed Filter for Municipal Wastewater Treatment: The Case Study of the Prototype Installed at Gaston Berger University, Saint-Louis, Senegal

Abstract

In Saint-Louis, Senegal, a constructed wetland with horizontal flow reed beds ( FHa and FHb) has demonstrated significant efficacy in treating m unicipal wastew ater. Analyzing various treatment stages, the system showed only a slight temperature variation, from an influent average of 26.3°C to an effluent of 24.7°C. Electrical conductivity decreased from 1331 mS/cm to 974.5 mS/cm post- pr imary treatment, with suspended solids (SS) dramatically redu ced from 718.9 mg/L to 5.7 mg/L in the final effluent. Biochemical oxy gen demand (BOD5) and chemical oxygen demand (COD) saw a notable de crease, from initial levels of 655.6 mg/L and 1240 mg/L to 2.3 mg/L and 71.3 mg/L, respectively. Nitrogenous compounds (N-TN) and phosphates ( ) also decrea sed significantly, indicating the system’s nutrient removal capacity. Micro biological analysis revealed a reduction in fecal coliforms from 7 . 5 Ulog/100ml to 1.8 Ulog/100ml and a complete elimination of helminth eggs. The p resence of Phragmites and Typha was instrumental in enhancing these reductions. The system’s compliance with the Senegalese standards fo r disposal into natural environments, WHO recommendations for unrestric ted water reuse in irrigation, and the European legislation for water reuse was established. The effluent quality met the stringent criteria for various classes of agricu ltural reuse, illustrating the system’s potential for sustainable water management. This wetland model presents a robust solution for water-stressed regions, ensuring environmental protection while supporting agricul tural needs. The study calls for ongoing research to further refine the system for optimal, reliable wastewater treatment and water resource sustainability.