This work was carried out to establish the effects of the activities of a cluster of industries in Jos-South Local Government Area of Plateau State, Nigeria, on the environmental quality of the industrial area. Some physicochemical parameters –temperature, pH, turbidity, suspended solids (SS), total solids (TS), total hardness, alkalinity, biological oxygen demand (BOD), chemical oxygen demand (COD), heavy metals (Cu²⁺, Co²⁺, Fe²⁺ & Zn²⁺), phosphates, nitrates, sulphates and chlorides –of the wastewaters from the various industries were investigated using standard protocols. Also, the influence of flow-distance on the empirical correlation between biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of the wastewaters was investigated. Wastewater samples were collected at point-sources and at 25, 50, 75 and 100m distances from the point-sources. Sampling was done twice a week for a full seasonal cycle at peak production period (morning and evening). The samples’ pH was adjusted to 7 using 0.5M acid for basic samples and 1.0M alkali for acidic samples, de-chlorinated using 0.0125M Na₂S₂O₃ and seeded when necessary and then diluted with de-ionized water. The ranges of the parameters were as follows: temperature: 22 –32°C, pH: 5.5 –10.4, SS: 0 –1,300 mg/L, TS: 200 –1.400 mg/L, sulphate: 0.37 –1.37 mg/L, nitrites: 0.10 –1.09 mg/L and phosphate: 14.80 –21.83 mg/L. The phosphate values, especially, were in excess of the maximum contamination limit specified by Federal Environmental Protection Agency (FEPA) and World Health Organization (WHO); and are capable of triggering eutrophication,which will in turn increase BOD/COD values. Concentrations of heavy metals, determined by Atomic Absorption Spectrophotometry (AAS), ranged as follows: 0.07 –2.01 mg/L for Cu²⁺, 0.58 –3.27 mg/L for Fe²⁺, 0.01 –3.18 mg/L for Zn²⁺ and 0.11 –0.18 mg/L for Co²⁺ whose specified standard is not available. BOD₅ values ranged between 5.34 –25.88 mg/L while COD values ranged from 727.30 –8,308.66 mg/L. Some BOD₅ values were in excess of the allowable limit while all COD values were observed to be very high. This implies an appreciable level of pollution exists here and recipient water bodies of these wastewaters are at risk of being polluted. COD and BOD₅ of the wastewaters from different sources highly correlated with correlation coefficients ranging 0.9396-0.9985. The empirical correlation between COD and BOD₅ was generally maintained despite the distance of flow of the wastewater from point-source and contributions of washings from farmlands and other human activities i.e. the correlation between COD and BOD₅ for wastewaters was not affected by flow distance. The correlation equations for the industries may, therefore, be used to deduce rapid effluent quality from chemical oxygen demand (COD) of sample from any point along the effluent flow path.
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