Enhancement of the soil quality of an oil-polluted ultisol using livestock wastes

Abstract

The study investigated the enhancement of soil quality of an oil-polluted ultisol using livestock wastes. Top soil (0 - 10 cm) was obtained as a pooled sample and polluted with spent lubricating oil at 10% w/w. The soil was subsequently amended with sun-dried goat (GT), rabbit (RB), and poultry (PG) dung at 10% w/w on dry weight basis both in singles, double-mixed, and triple-mixed combinations. Twelve weeks after treatment application, results showed that there was a 93.9% decrease (p<0.05) in bacterial colony count in the oil-polluted soil compared to the control. Penicillium notatum and Aspergillus niger as well as Bacillus sp. and Proteus sp. were the prominent fungal and bacterial species identified respectively. The most abundant plant in the soil seed bank was Panicum maximum with 10.4% abundance and this showed possible involvement of the plant in remediation of oil-pollution. The total hydrocarbon content of the oil-polluted soil was 9984.0 mg/kg, compared to 3170.6 mg/kg when amended with RB+GT, implying 76.77% remediation efficiency. Among several trials employed in this study, the combination of rabbit and goat wastes proved to be more effective in reducing the total hydrocarbon content of oil-polluted soil and therefore, is recommended as a potential candidate for application in the bioremediation of such soil.

Keywords

• bioremediation; pollution; remediation efficiency; soil amendment; ultisol; waste engine oil