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Microbiological and physicochemical properties of waste lubricating oil polluted soil were studied for 35 days. The results show that bacteria and fungi population in oil free soil (OFS) were higher than that of oil polluted soil. The bacteria counts ranged from 0.24 x106 to 140 x 106 cfu/g for OFS and 0.24 x106 to 40 x106 cfu/g for OPS while the fungi counts ranged from 7.0 x 106 to 21 x 106 cfu/g in OFS and 7.0 x 106 to 19 x 106 cfu/g in OPS. There were significant differences in the counts of bacteria and fungi obtained from OFS and OPS at 5% probability level. Nitrogen, available Phosphorous, Organic matter content, Iron, Nickel, Lead, Copper and Zinc were higher in polluted soil than in the oil free soil. There were no significant differences (p<0.05) in pH, Nitrogen, Organic carbon, 0rganic matter content, Iron, lead, Copper, Zinc and Nickel in both OFS and OPS. However, there was a significant difference in the concentration of Phosphorous (p>0.05) in the soil samples analysed. The organisms isolated were species of Pseudomonas, Bacillus, Micrococcus, Staphylococcus, Aspergillus, Candida, Mucor, Penicillium and Rhizopus. The results obtained suggest accumulation of heavy metals in the soil as a result of waste lubricating oil pollution.
Key words: waste oil, pollution, trace metals, microbiological properties