REMEDIATION ABILITY OF MELON GRASS IN A CRUDE OIL POLLUTED SOIL IN A TROPICAL REGION

The aim of this research was to study the effectiveness of a chosen grass (plant) in the remediation of soil contaminated by crude oil. Lemon grass was used in this study to remediate the polluted soil because of its perceived ability to do so. Five wooden boxes were fabricated, and 150kg of soil were introduced to each of them. Four of the boxes were contaminated with different concentrations of crude oil, while two out of these four boxes were amended with cow dung. One of the boxes that served as control was neither contaminated nor amended. Lemon seeds were then planted in all the boxes and allowed to grow for the period of 12 weeks. Analysis were done at the beginning, during and after the plant growth in order to determine the rate of remediation, with particular interest in the TPH (total petroleum hydrocarbon), and few other heavy metals; copper, magnesium, aluminum. Two concentrations of contamination were artificially made (75g and 150g). The TPH, Pb, Zn and Ni contents of the 75g crude oil contaminated soil were 6.784µg/g, 0.485mg/kg, 0.867mg/kg and 0.030mg/kg respectively. It reduced to 6.356µg/g, 0.058mg/kg, 0.560mg/kg and 0.043mg/kg respectively after remediation. The TPHPb, Zn and Nicontents of the 150g crude oil contaminated soil were 9.109µg/g, 0.699mg/kg, 0.851mg/kg and 0.032mg/kg respectively. It reduced 7.713µg/g, 0.059mg/kg, 0.506mg/kg and 0.057mg/kg respectively after remediation. An interesting observation was that, amending the contaminated soil with cow dung gave a favourable result in remediating the contaminants. It took about 80months to remediate TPH to an acceptable level of 0.013µg/g, but over 150months to do the same for an unamended soil. This finding can be applicable in the estimation of time requirement for the remediation of crude oil polluted soil by concerned stake holders.