Characterization of Effluent Discharge From Tanneries in Challawa Industrial Estate, Kano, Nigeria Using Physicochemical-based Indices

This study was conducted to characterize the effluent discharge of some tanneries in the Challawa Industrial Estate, Kano. Tannery operations consist of converting raw hide or skin to leather, which can be used in the manufacture of a wide range of products. Effluents were collected at the discharge point of each of the tanneries. Ex-situ analysis of the effluent samples for Total Suspended Solid (TSS), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Chromium, Cadmium, Chloride, Nitrate and Sulphide were determined using Standard Methods. Concentrations of Chromium ranges from 1.0mg/l to 2.4mg/l. The lowest value of 1.0mg/l was recorded in Mamuda Tannery and the highest value of 2.4mg/l in Fine Leather. Chloride ranges from 2415.5mg/l to 10929.9.Concentration of nitrate ranges from 591.2mg/l to 2814.0mg/l. the lowest value was recorded in Mamuda Tannery while the highest value was from Fine Leather. Cadmium concentration ranges from 0.006mg/l to 0.02mg/l, while Sulphide ranges from 54.7mg/l to 99.7mg/l. The concentrations of all ex-situ parameters except for Cadmium were higher than standard permissible limits (PL) set by the National Environmental Standards and Regulations Enforcement Agency (NESREA) for Textile, Wearing Apparels, Leather and Footwear Industries, Regulation 2009. These tanneries discharge their effluents into canals that eventually flow into the nearby Challawa River which is used for agricultural purposes by local farmers. Thus, the discharged tanning effluent in Challawa Industrial Estate, Kano pollutes the Challawa River. Based on the findings from this study, the following recommendations are made: Proper treatment of wastewater from the tanneries should be carried out to ensure all pollution parameters concentration are below the maximum permissible limits (PL) of regulating authorities before discharge; regulatory authorities need to embark on routine inspection and assessment of effluent treatment plants of tanneries to ensure proper treatment of effluents before it is discharged; secondary treatment plant should be installed in tanneries to treat primary effluents.