Comparative Studies on the Efficacy of Azadirachta indica and Moringa oleifera in Phytoremediation of Some Selected Heavy Metals from Contaminated Soil

This research was carried out to investigate the efficacy of Azadirachta indica (Neem) and Moringa oleifera (Drumstick) in phytoremediation of heavy metals (Ni, Pb and Zn) from the potted contaminated soil. The three selected heavy metals were used to pollute three blocks; each block was subdivided into two subsets of three replicates each per the heavy metal. The two studied plants were transplanted from the nursery into each bag containing contaminated soil. The result of the metal accumulation at the roots of the studied plants indicates that A. indica had the higher mean value of Ni, Pb and Zn absorption (170.0 mg/kg, 119.1 mg/kg and 1.5 mg/kg respectively), whereas the M. oleifera had a lower mean value (0.4 mg/kg, 118.2 mg/kg and 0.9 mg/kg), with no significant difference. The levels of heavy metals in the soil containing A. indica was lower with variation in the level of Pb (p=0.043) but the levels of Zn and Ni (p=0.380 and p=0.144 respectively) was not significant. The bioaccumulation factor shows that A. indica accumulates a higher concentration of heavy metals. This research reveals that both studied plants accumulate high concentration of Ni, Pb and Zn at its root, though A. indica is shown to possess greater ability in accumulating heavy metals.