Laboratory of Soil, Water and Geomaterials Sciences (LSSEG), University Félix Houphouet-Boigny, Training and Research Unit for Earth Sciences and Mineral Resources, Abidjan, Côte d’Ivoire
The city of Grand-Bassam in the south-east of Côte d'Ivoire is faced with a sanitation problem, the direct consequence of which is the untreated discharge of wastewater into the Ouladine lagoon. This work aims to determine the physico-chemical and metallic quality of urban wastewater discharged into the Ouladine lagoon without treatment. The samples were taken respectively during the dry season (March 2021) and the rainy season (June 2021) on seven (07) outlets of the pipes. The pH, temperature, and dissolved oxygen (O2) were measured in situ using a multi-parameter HANNA HI 9829. Parameters such as Chemical Oxygen Demand (COD), and Total Suspended Solids (TSS) were measured in the field with a portable multi-parameter spectrophotometer Pastel UV - Secomam. The various physico-chemical and metallic parameters were analysed in the laboratory according to the analysis methods recommended by the French normalisation association (Association Française de Normalisation). The results obtained show that the parameters studied (T, pH, DO, COD, TSS, TKN, Pt, As, Cd and Pb) have variable contents from one site to another. Most of the parameters exceeded the limit values recommended by Ivorian regulations for wastewater, except for the levels of metals, which remained low at all sampling points. According to the results of this study, a municipal wastewater treatment system must be set up to discharge a liquid effluent that complies with Ivorian regulatory requirements.