Phytoaccumulation of Heavy Metals in a Waste Engine Oil-contaminated Soil by Aspillia africana After Exposure to Hydroxyl Amine Hydrochloride Pre-treatment

Abstract

This study employed the use of NH2OH.HCl in the pre-treatment of Aspilia africana for the phytoremediation of waste engine oil-contaminated soil for a period of three months. 8 kg of soil was obtained, weighed and polluted at 5% W/W of waste engine oil which was replicated in 18 buckets and left for a period of one month to attenuate naturally before sowing with stems of Aspilia africana which were treated with four different concentrations of NH2OH.HCl (0.03125%, 0.0625%, 0.1250% and 0.2500% w/v) by soaking in the solution for one hour after which the planted stems were exposed for another two months with vegetative and physico-chemical parameters measured. The control was treated in distilled water (i.e. 0% w/v). Concentrations of heavy metals as well as Polyaromatic hydrocarbon in the contaminated soil were high after contamination and thus would normally be expected to impact the nutrients in the soil responsible for plant growth; with Cu present at a concentration of 26.24 mg/kg at 1 month after contamination (MAC) as compared to their none availability in the soil before contamination. As the plants matured with increase in time however, heavy metal concentrations in the soil decreased to the barest minimum in the soil with Cu (26.24 mg/kg at 1 MAC) been remediated to 0.40 mg/kg at 3 MAC using 0.0312% concentration of NH2OH.HCl treated Aspilia africana. It was observed that a considerable amount of Heavy metal concentrations in the contaminated soil were gotten rid of in the soil within the three months period that the experiment was carried out. Phytoremediation technology had worked for the degradation of contaminants in the soil and thus rendered the soil good for other useful purposes including agriculture and also to be kept for future reclamation activities. It is expected that further studies on this method of remediation will expose us to greatly appreciate nature’s gift of cleansing our environment for mankind.