Phytoremediation of Pb, Cd and As from Urban Solid Waste Compost Using Tithonia diversifolia (Hemnsl.) A. Gray and Ageratum conyzoides L.

Abstract

Soil and water contaminated with heavy metals pose a major environmental and human health problem in Nigeria. This study was carried out to ascertain the presence of heavy metals in Urban Solid Waste Compost (USWC) and examined the potentials of Tithonia diversifolia and Ageratum conyzoides in remediating heavy metals constituents of USWC. The study was carried out in the crop garden of the Department of Crop Production, Olabisi Onabanjo University, College of Agricultural Sciences, Ayetoro. The trial was a completely randomized design with four replicates. The treatment was made of two plant species belonging to Compositae family and USWC obtained from three different dump site locations in Ayetoro and a control.Two seeds of the two plant species were sown in pots containing 20kg of USWC and grown for 12 weeks. Data were subjected to analysis of variance and means separated by LSD at p≤ 0.05. At the commencement of the trial, the concentration of Pb, Cd and As in the USWC from the three dumpsites averaged 15mg/kg, 0.53mg/kg and 0.15mg/kg respectively. Post trial analysis showed that Pb, Cd and As contents of the USWC was reduced by 97.99%, 75.90% and 11.69% respectively. Uptake of Pb (t α =0.05 = 0.36), Cd (t α =0.05 = 0.64), and As (t α =0.05 = 0.91) by the two plant species were not significantly (p<0.05) different. Partitioning of the pollutants was more in roots (Pb = 15.15 mg/kg, Cd = 0.57mg/kg and As = 0.13mg/kg) than shoots (Pb = 14. 89mg/kg, Cd = 0.49mg/kg and As = 0.15mg/kg). The implication of the results for the quality of arables produced at urban and peri-urban roadside gardens as well as human health and environmental problems are discussed.