Phytoremediation of Spent Oil and Palm Kernel Sludge Contaminated Soil Using Sunflower (<i>Helianthus annuus</i>) L

Abstract

This study was carried out to investigate the phytotoxicity of spent engine oil and palm kernel sludge on seed germination, seedling early growth and survival of sunflower (Helianthus annuus L) and its phytoremediating potential. 8.0 kg topsoil mixed with 2, 4, 6, 8 and 10% (w/v) of spent engine oil and palm kernel sludge, while the control was not mixed with spent oil and sludge (0%). The seeds were sown on these soils and monitored daily. Parameters taken were; plant height, leaf number and stem girth. The result showed that spent engine oil treated plants adversely affected growth compared to palm kernel sludge plants and control which performed better. For plant height, the mean stem girth for control at 2nd week was 0.40±0.05 mm, spent engine oil was 5.96±0.97 palm kernel oil effluent was 14.73±1.16 and at 12th week, control was 1.30±0.05 while for SEO the plant had withered and 124.6±9.02 for POE. Number of leaves at the 12th week was 26.00±2.08 in the control, 8.66±0.66, for spent engine oil at 4%, while for palm oil effluent it was 27.66±0.66, at 4%, concentration respectively. Stem girth at 2 weeks for spent engine oil was 0.19±0.05 at 2%, 0.43±0.03 for palm kernel oil effluent and at the 12th week of planting at 10% concentration was 1.63±0.08 for palm kernel oil effluent, and all plants had withered off for spent engine oil at same concentration at the 12th week. Also, spent engine oil at all concentrations delayed the germination of Helianthus annuus by 2days compared to control. Comparison analysis test showed that growth in untreated plants were significantly higher (p>0.05) than spent oil and palm kernel sludge treated plants. Similar result was observed for leaf number and stem girth which had higher mean value in palm kernel sludge and control compared to spent oil. Sunflower grown in 8% and 10% palm kernel sludge contaminated soil also flowered eight days earlier than control plants, while spent oil treated plant did not. The result shows that sunflower cannot tolerate high (4%, 6%, 8% and 10%) concentrations of spent engine oil in soil compared to palm oil effluent. Therefore, spent engine oil should be properly disposed because of its adverse effect on the growth and yield of sunflower.