The effects of brewery effluent discharge on the water quality and sediment of the Ikpoba River, Benin City, Nigeria

Abstract

The Ikpoba River is a major source of potable water supply in Benin City, Nigeria. Four stations, 1 (upstream discharge point), 2 (discharge point), 3 (downstream) and 4 (further downstream) were assessed for impact. DMR test showed that station 2 had significantly higher (P<0.05) mean salinity (0.16 ‰), turbidity (17.04 NTU), TSS (16.38 mg/l), TDS (177.33 mg/l), HCO3 (192.92 mg/l), COD (62.98 mg/l), conductivity (338.17 ìS/cm), Na (52.50 mg/l), K (18.87 mg/l), PO4 (0.52 mg/l) and Cu (0.07 mg/l) All sediment parameters showed no significant spatial variation. The  concentrations of heavy metals Cr (0.08 mg/l), Ni (0.17 mg/l), Cu (0.07 mg/l), Fe (1.83 mg/l) and Pb (0.04 mg/l) exceeded the regulatory limits for potable water and aquatic life, while DO was lower than the  recommended limit of 5 mg/l in stations 2 and the downstream stations. The distribution coefficient showed low sorption capacity (Kd) for Cr (4.36), V (5.6) and Ni (6.11). Effluent discharge into the river significantly altered the water quality. Monitoring of effluent discharge into the aquatic  environment and strict adherence to regulatory limits will halt further  degradation of the environment.

Key words: Water, sediment physico-chemistry, distribution coefficient, effluent discharge, tropical river