Numerical Modelling of Latitudinal Migration of Spent Engine Oil Contaminants in a Lateritic Soil.

Abstract

Abstract Despite the overwhelming advantages recorded through the establishment of automobile mechanic villages, the anti-ecologically friendly practices recoded within the developing countries seek urgent and integrated approach in order to cub the rising menace associated with these unethical practices. Indiscriminate discharge of spent engine oil on the soil and many other pollutants known to contain high levels of heavy metals and Polycyclic Aromatic Hydrocarbons is in no doubt causing serious ecological and public health concerns. Therefore, this research work focuses on using Classical Diffusion, Advection-Dispersion Model in evaluating the final concentration (C) of the Spent Engine Oil(SEO) sample constituents (PAHs, Lead, Cadmium and Nickel) emanating from the study area (Nekede Mechanic Village, Owerri, Imo state, Nigeria). The model prediction proved that under high rainfall density, high infiltration rate and favourable geologic conditions recorded in the area, high levels of the contaminants could be possibly transmitted to the groundwater table of the study area. Soil sample was collected from a depth of 35cm within Nekede mechanic Village for the purpose of ascertaining its physico-chemical properties. A sample of SEO was collected from an auto-mechanic shop for the purpose evaluating the initial Concentration (Co) of the contaminants/ constituents of SEO. Analytical result shows the total initial volume of 16 Polycyclic Aromatic Hydrocarbon (PAHs) contained in the sample of Spent Engine Oil to be 51.73329 (ppm). The initial concentrations of three selected Heavy metals were evaluated; lead (Pb) 112.04mg/L; Cadmium (Cd) 3.020mg/L; Nickel 2.130mg/L. The Classical Diffusion, Advection/Dispersion Model was used to predict the concentration of the SEO constituents at 24m depth, using the data from the analytical results of the SEO and the soil analysis as inputs. The modelling predicted reduction in volume of SEO constituents as they migrate down the soil. Hence, the results derived proved that SEO constituents could exceed the Maximum Contaminant Levels (MCLs) under a steady flow. Therefore, proper Spent Engine Oil management and environmentally friendly mechanic villages should be encouraged.