Purification performances of common reed beds based on the residence time: Case of Benin

Abstract

Introduction: To avoid ecological and human disasters due to the release of huge amounts of domestic waste, wastewater treatment facilities must be built immediately. One solution is to apply an organic treatment technology. Organic treatments are cheap, efficient, and require little electric energy.
Objective: This study aims to determine the purification performances of common reed beds in order to facilitate their implementation in Benin.
Methodology and Results: A test station, which utilizes vertical flow filters planted with phragmites, was built to treat the Abomey-Calavi campus’s domestic sewage in Benin. This sewage treatment plant was tested for 3 months. At the beginning of the study, the untreated sewage had concentrations of 3240 mg/L; 850 mg/L; 7400 mg/L; 168 mg/L; and 4.5 mg/L respectively in Chemical Oxygen Demand (COD), Biochemical Oxygen Demand at 5 days of incubation (BOD₅), Total Suspended Solid (TSS), Total Kjeldahl Nitrogen (TKN), and Total Phosphorus (TP). At the end of the study, the treatment performance results showed the following removal rates: COD (93%), BOD₅ (92%), TSS (98%) and TKN (99%). The removal rates are within the Beninese standards set by the decree n°2001-109 of April 4, 2001 which set the minimum removal rates at75%, 70-90%, and 90% respectively in COD, BOD₅, and TSS.
Conclusion and application of results: Despite the use of a single stage, good results were obtained. Indeed, this study’s removal rates are within the Beninese standards. The reed bed wastewater treatment process is simple to build, to make functional and to maintain. This process is also cheap to build. Owing to its advantages, the reed bed is a solution to Beninese purification problems. Since technical service agent of the municipalities can quickly and easily build, make functional and maintain a reed bed plant.

Keywords: common reed beds, domestic wastewater