Phytoremediation of copper and zinc in sewage sludge amended soils using jatropha curcas and hibiscus cannabinus

Phytoremediation can be potentially used to remediate heavy metal contaminated soils. A glasshouse experiment was conducted to determine the extent of Jatropha curcas and Hibiscus cannabinus efficiency to the remediation of zinc and copper contaminated soils amended with sewage sludge. An Oxisol (Munchong Series) and an Ultisol (Bungor Series) were used in this experiment, which was laid out using a randomized completely block design in six replication. The plants in pots having soil containing 0, 5 and 10% (w/w) sewage sludge were grown for six months. Phytoremediation can take place successfully as shown by the decrease of total Zn and Cu in the treated soils, where the concentrations of Zn and Cu in the tested soils were higher before planting as compared to after planting. Most of the Zn and Cu taken up by the tested plants were stored in the shoots (leaves+ stem). The fractionation of Zn and Cu in sewage sludge, untreated and treated soils was studied before and after planting. The results of the fractionation study showed that the dominant Zn and Cu in the soil were in their residual form. At harvest, the percentages of water soluble and exchangeable fraction were increased, implying that some of the residual fraction may have changed to other forms. In general, there was no significant difference between the different metal fractions in the Oxisol and Ultisol. (author)