Evaluation of the Purification Performance of the Kossodo Wastewater Treatment Plant in Ouagadougou

Abstract

The efficiency of a wastewater treatment system is classically measured by the quality of its discharge into the aquatic environment. This quality can only be achieved if certain aspects are taken into account, such as the design and operation of the system in place. The objective of the present work is to evaluate the purification performance of this system after 17 years of operation. It should be noted that the lagoon plant (WWTP) has a total of eight basins, three of which are anaerobic (ANA). The evaluation of the physicochemical and microbiological parameters in the anaerobic basins and in the maturation basins allowed us to note slightly basic pH values in the maturation basins (8.7 to 9.2) against values from 6.8 to 7.4 in the anaerobic basins. Also, the values in terms of organic and bacteriological pollution have also evolved. For COD and BOD 5 , we obtained respectively abatements of more than 73% for filtered COD, 55% for gross COD and 81% for BOD 5 even if the residual concentrations do not respect the standards of wastewater discharge in our country. Also, the residual concentrations of ammonia nitrogen in the output effluents (on average 12.43 mg/L), do not meet the standard of discharge into surface waters of Burkina Faso (1.29 mg/L). Thus, nutrients such as nitrogen and phosphorus pollution have average abatement rates of 31% and 27% respectively. In sum, we can say that the lagoon system set up does not meet the requirements in terms of quality of discharges, which remains an environmental problem for the receiving environment.