Bioremediation Effects of Nitrogen Fixing Trees on Nutrients and Heavy Metals in Spent Engine Oil Polluted Soil

Abstract

Soil contamination by spent engine oil is a growing concern in many countries, especially in some less developed countries such as Nigeria. Greenhouse experiment was conducted for 4 months using Leucaena leucocephala to determine its effect on the nutrients (N, P, K, organic carbon) and heavy metals (Zn, Ni, Pb, Cu) of soil polluted with spent engine oil [5% (w/v)]. Soil without spent engine oil was used as control. Bioaccumulation of the nutrients and heavy metals in Leucaena leucocephala was also determined. Reductions in the nutrients were observed in the soils during the first to third months of bioremediation. However, in the fourth month, 33.33% and 16.67% increase in nitrogen were recorded in the control and polluted soils, respectively. Reduction in Zn, Ni, Pb, and Cu was 41%, 48.39%, 61.60%, and 52.72%, respectively, in the polluted soil, and bioaccumulation of Zn, Ni, Pb, and Cu in Leucaena leucocephala planted in the polluted soil increased by 73.41%, 85.46%, 3366.04%, and 125.53% in the plant biomass. This chapter has shown that Leucaena leucocephala is effective in bioremediation of heavy metals in spent engine oil-polluted soil.