International Journal of Environmental Pollution and Environmental Modelling
Yazarlar: Daniel Gbadesere AKİNTUNDE, Olukayode BAMGBOSE
Anahtar Kelimeler:industrial wastewaters, water quality, discharge point, upstream, downstream
Özet: This study determined the seasonal impacts of wastewaters from Ikeja industrial estates on the water quality of proximate Iya Alaro River being one of the longest rivers employed for irrigational and washing purposes in the estate. Wastewater samples from industrial estate were collected at the point of discharge of effluents into the streams and at spatial interval of 50 to 200 meters upstream and downstream of the discharge point over a two- year period (2005-2007) .The effluents were analysed for physico-chemical parameters using standard methods. At discharge point during dry and rainy seasons, the pH were acidic (5.51 ± 0.16 to 6.46 ± 1.27 and 6.13 ± 0.96 to 6.80 ± 1.04).Total Dissolved Solid and Electrical Conductivity levels showed significant difference (p < 0.05) between seasons at discharge points and higher than permissible levels at upstream and downstream. Mean levels of Dissolved Oxygen (DO) were low at discharge points during the dry and rainy seasons (2.20 ± 0.66 to 3.93 ± 0.71 and 2.41 ± 0.30 to 2.83 ± 0.72). Biochemical Oxygen Demand and Chemical Oxygen Demand increased in the range of 579-1186 mg/L and 1247-2610mg/L respectively from March to July with low levels of DO ranging from 1.70 to 3.70 mg O2/L. Mean levels of Nitrate were within permissible limits downstream and upstream and higher in rainy than dry seasons at the discharge points. Sulphate levels detected were below WHO levels of 400mg/L while Chromium levels were above the limits of 0.05 mg/L. Mean levels of Phosphate at discharge points was higher (31.97 ±1.12mg/L) during dry season of the second year, and were also higher upstream and downstream than permissible limits. Manganese showed significant difference (p < 0.05) at the discharge points. Downstream accumulations were relatively higher for Copper (4.04mg/L) and Manganese (4.10mg/L) in the dry season and Cadmium(5.93mg/L) in the rainy season. It showed that industrial wastewater majorly caused the stream to be polluted and unsuitable for drinking. The degradation of the water quality of proximate streams in the estate therefore needs preventive and remedial measures of combined central effluent and treatment plants in order to bring back the waters to a level before the pollution discharges.