Benin City, Industrial effluent, Physicochemical, Stream, Water quality
An investigation of the impact of industrial effluent discharged into Eruvbi stream was carried out in the wet season months of March to August, 2009. Water samples from three selected points in the stream were analysed for temperature, total dissolved solids, turbidity, pH, electrical conductivity, dissolved oxygen, biochemical oxygen demand (BOD5), total alkalinity, chloride, hardness, calcium, magnesium and nitrate. Samples were collected at three sites, designated as station 1 (upstream of effluent discharge point), station 2 (effluent discharge point) and station 3 (downstream of effluent discharge point). Water temperature, turbidity, alkalinity, hardness, calcium and magnesium were found to be significantly higher at the discharge point (Station 2). The parameters when compared with Federal Environmental Protection Agency (FEPA) limit for discharge into Nigeria surface waters and WHO guidelines, turbidity in stations 2 and 3 were found to exceed the maximum allowable limit (5NTU) while dissolved oxygen level at all stations were lower than the minimum allowable limit (5mg/L) for aquatic life. All other physiochemical parameters including biochemical oxygen demand were below the recommended limits in all stations. This physico-chemical regime is an indication of the deteriorating water quality of the stream at the discharge point and downstream due to the effluent inflow.
Keywords: Benin City, Industrial effluent, Physicochemical, Stream, Water quality