ABSTRACT
Spent engine contaminated soil was obtained from a mechanical work, from an automobile mechanic workshop at Ugbowo in Egor L.G.A., Benin City, Edo State and fresh cow dung was collected from a cattle ranch in Ekosodin, Ovia-North East LGA, Benin city, Edo State. The samples were sundried for a period of two weeks, reduced into a particle size of 2mm and characterized in term of physical and chemical properties. Approximately, 1000mg/kg of spent engine oil contaminated soil was weighed into four different beakers and various amount of organic waste were added; flask A contained oil-contaminated soil without cow dung biomass (CDB), and flasks B, C, and D contained oil-contaminated soil with, 5, 45 and 65g of CDB, respectively which was maintained at 60% water retention(WRC) for a period of 7 week. The analysis of the soil samples revealed the following properties: a pH value of 7.29 ± 0.09, electrical conductivity (EC) of 101.30 ± 0.92 µS/cm and bulk density of 1.31 ± 0.00 g/ml. Furthermore, the result demonstrated that the soil contains significant amounts of essential nutrients, including Nitrogen (3.50 mg/kg), Phosphorous (5.80 mg/kg), Potassium (11.7 mg/kg), Sodium (29.0 mg/kg), Calcium (9.0 mg/kg), and Magnesium (34.00 mg/kg). More importantly, the concentrations of specific heavy metals in the soil were found to be below established threshold values considered safe for soil.
