IMPROVEMENT OF WASTEWATER TREATMENT FOR AGRICULTURAL REUSE IN THROUGH A SYSTEM CONSISTING OF SEDIMENTATION BASIN AND HORIZONTAL SUBMERGED FLOW CONSTRUCTED WETLAND, IN THE TECHNOPOLE AREA OF DAKAR, SENEGAL

The present research aims to study the improvement in the performance of wastewater treatment within the WWTP of the Technopole area of Dakar through a system consisting of a septic tank and a horizontal submerged flow constructed wetland, planted with reeds. A volume of wastewater equal to 2000 L is treated daily. The pretreatment function performed by the septic tank leads to a removal yield of 48.7% for TSS, 49% for BOD, 31% for COD and 77% for E. coli compared to inlet wastewater. After a stay of 24 hours inside the septic tank, the clarified wastewater passes through a horizontal flow constructed wetland. The removal yields are 91% for TSS, 82% for BOD, 75% for COD and 99.5% for E. coli with respect to inlet wastewater. However, even after the treatment and the storage, some outlet parameters, such as E. coli, did not meet the limits of WHO and FAO guidelines for the reuse of treated water for irrigation nor the Senegalese standard for the discharge of wastewater. Therefore, disinfection through bleach was used to improve the treatment. Results after disinfection reported a complete removal of E. coli, yields of 97% for BOD and 68% for COD