Taofique Assi¹, Tomkouani Kodom^1,, Ibrahim Tchakala¹, Moctar Limam Bawa¹

The purpose of this work was to highlight the potential impact of the leachate generated by the Aképé technical landfill center on the physicochemical quality of groundwater in it vicinity. Thus, physicochemical characterizations of the raw leachate and the leachate from the infiltration basin which constitutes the post-treatment leachate and the water from three piezometers available on the site were carried out. To assess the pollution level of the leachate and groundwater, the statistical tools such Leachate Pollution Index (LPI), Water Quality Index (WQI) and Principal Component Analysis (PCA) were used. Five sampling campaigns were carried between May 2022 to May 2023. Raw leachate (taken just at the entrance to the aeration basin), treated leachate (taken from the infiltration basin) and water from the piezometers are taken during each campaign. Analysis of the raw leachate showed high minerals content, organic and metallic pollutant load (average chloride concentration: 5425.96 mg/L, sulphates: 256.33 mg/L, COD: 7420 mg/L, BOD5: 255 mg/L, copper: 0.20 mg/L, zinc: 0.27 mg/L, lead: 0.13 mg/L and cadmium: 0.03 mg/L) with an average LPI of 128.54. In addition, a significant pollutant load in the leachate of the infiltration basin was noticed (chlorides: 3103.41 mg/L, sulphates: 67.92 mg/L, COD: 2580 mg/L, BOD5: 20.90 mg/L, copper: 0.15 mg/L, zinc: 0.03 mg/L, lead: 0.11 mg/L and cadmium: 0.02 mg/L), with an LPI of 92.97. These leachates were respectively classified as “very high pollution” and “high pollution”. This high pollution load of leachate makes the surrounding groundwater vulnerable. The physicochemical study of water from the piezometers revealed a significant deterioration in ground water quality. Calculation of the water quality index (WQI) for piezometers P1, P2 and P3 gives values of 17.75; 36.13; 269.32 respectively. According to the classification, waters from P1 and P2 are characterized by good quality while P3 is very poor quality. Piezometer P3 is the most polluted with high mineralization (EC = 7466 μS /cm) and high chloride concentrations (1339.90 mg/L), testifying the potential contamination by leachate from the basin of infiltration given to their proximity. The PCA confirmed this pollution showing anthropogenic origin of the majority of chemical elements, especially in piezometer 3.

technical landfill, leachate, leachate pollution index, groundwater, water quality index