Potentials of Using Moringa oleifera Seeds in the Bioremediation of Soil Contaminated by Crude Oil

Abstract

The potential of using Moringa oleifera seed cake to increase the rate of the microbial degradation of crude oil-spilled soil was investigated. This investigation was carried out at the National Research Institute for Chemical Technology, Zaria, Nigeria, within a 28 day period in the month of May, 2012. The proximate analysis of Moringa oleifera seed cake was found to contain nitrogen (10.55%), phosphorus (18.33 ppm) and organic carbon (1.06%). Likewise hydrocarbon degrading bacteria were isolated using spread plate method. The results revealed that the counts of crude oil degrading bacteria in crude oil polluted soil amended with Moringa oleifera (sample C) increased to 3.6 x 106 CFU/g, with a growth rate constant of 0.06 as compared with that of unamended polluted soil (sample B), whose counts increased to1.5 x 106 CFU/g, with a growth rate constant of 0.019. Moringa oleifera seed cake was found to enhance the degradation in crude oil polluted soil compared to unamended crude oil polluted soil by 64.3%. pH of crude oil polluted soil sample amended with Moringa oleifera seed cake ranged between 7.24 and 7.70 while that of unamended crude oil polluted soil ranged between 7.24 and 7.44. This implies that Moringa oleifera has a buffering effect which enables micro-organisms to proliferate. Statistical analysis showed no significant difference (p>0.05) between rate of biodegradation of crude oil in soil amended with Moringa oleifera seed cake as against that of unamended crude oil polluted soil. The results of this study show that Moringa oleifera seed cake is suitable for bioremediation of crude oil polluted soils.