Pollution of the Chari River in the Slaughterhouse Farcha (N'djamena) in Chad

Abstract

This study was carried out to evaluate the influence of the discharge of effluents Farcha slaughterhouses pollution of the Chari River. To overcome this, water and sediment samples were taken upstream to the outlet and downstream of Farcha slaughterhouse. These samples were subjected to some physicochemical analysis. Slaughterhouse effluent showed a Chemical Oxygen Demand (COD) ranging from 96 mg.L-1 to 100 mg.L-1 ; Biochemical Oxygen Demand (BOD 5) 54 mg.L-1 to 70 mg.L-1 and the suspended solids (TSS) 64 mg.L-1 to 108 mg.L-1. The physicochemical characterization of water samples Chari gave a change in hydrogen potential (pH) between 6 to 7; a temperature ranging from 28.35°C to 28.70°C with an electric conductivity ranging from 50 µS.cm-1 to 129 µS.cm-1. The dissolved oxygen levels in water shows an appreciable oxygenation (5.02-7.37 mg O 2 .L-1). As the mineral substances, the chloride ions (Cl-) vary from 9.05 mg.L-1 to 29.25 mg.L-1 ; ferrous ions (Fe 2+) of 0.48 mg.L-1 to 11.10 mg.L-1 ; sulphate ions (SO 4 2-) of 21.50 mg.L-1 to 38 mg.L-1 ; phosphate ions (PO 4 3-) of 20.45 mg/L to 84.35 mg/L; nitrate ions (NO 3-) of 15 mg.L-1 to 39.50 mg.L-1. In opposite, the concentrations of nitrite (NO 2-) increased from 7.45 mg.L-1 to 13 mg.L-1 ; that of ammonium ions (NH 4 +) 1.49 mg.L-1 to 4.95 mg.L-1. The concentrations of dissolved ions showed higher values in July than in September. We observed significant variations in these parameters, some of which values were in excess of the WHO standard. However; the rate of COD/BOD 5 = 1.67 show that these wastewater Farcha slaughterhouses are biodegradable.