Efficacy of Urena lobata in Phytoremediation of Spent Engine Oil Polluted Soil

Purpose: The research study aimed to determine the efficacy of Urena lobata in phytoremediation of spent engine oil polluted soil of Makurdi, Nigeria as to determine the amount of some inorganic pollutants (Cd, Pb, As and Cr) removed from the soil by the annual plant with time.  Methodology: Urena lobata was grown in twelve (12) Plastic containers filled with four kilograms (4 kg) of sandy-loam soil contaminated with 0 mL, 20 mL, 40 mL, 60 mL, 80 mL and 100 mL and monitored for twelve weeks (12) after planting. Findings:  The tissue analysis of heavy metals shows that Urena lobata has the highest percentage absorbance and remediation capacity of arsenic (0.06 mg/kg) with percentage absorbance of 37.5 % and followed by cadmium 0.04 mg/kg of pollutant with percentage absorbance of 32.56 %. Equally, from the result and analysis obtained on remediation of lead pollutant, Urena lobata has remediation capacity of 0.11 mg/kg with percentage absorbance of 8.53 %. Also, Urena lobata has absorbance and remediation capacity of chromium pollutant with the mean tissue concentration level of 0.26 mg/kg. The absorption rate by the test plant measured were spent engine oil concentration level dependent. Finally, the results showed that the studied plant (Urena lobata) screened for total metal concentration showed value of bio-concentration factor (BCF) < 1 for all heavy metal pollutants, and also high value of translocation factor (TF) > 1 in the following order; Pb (2.000) > As (1.667) > Cr (1.567) > Cd (1.500) mg/kg and as a consequence Urena lobata plant was efficient in translocation of metal pollutants from roots to shoots. Unique contribution to theory, practice and policy: Urena lobata can then be considered as potential candidates for phytoextraction and phytoremediation of soils contaminated with Cd, Pb, As and Cr. Facility owners and industrialists should adopt and invest on the use of phytoremediation technologies in the remediation of polluted sites with spent engine oil as the technology can remediate more than one pollutant at a time and environmentally friendly.