Oil Palm Empty Fruit Bunch and Sugarcane Bagasse Enhance the Bioremediation of Soil Artificially Polluted by Crude Oil

Contamination of soil by petroleum hydrocarbons is becoming prevalent in Malaysia. Infiltration of soil contamination into groundwater poses a great threat to the ecosystem and human health. Bioremediation can occur naturally or can be enhanced with supplementation of microorganisms and fertilizers. However, fertilizers are expensive and therefore alternative nutrient-rich biomaterials are required. In this study, two organic wastes from agricultural industry (i.e., sugarcane bagasse and oil palm empty fruit bunch) were investigated for possible enhanced bioremediation of soil contaminated with Tapis crude oil. Two bacterial strains isolated and characterized previously (i.e., Pseudomonas aeruginosa UKMP-14T and Acinetobacter baumannii UKMP-12T) were used in this study. Sugarcane bagasse (5% and 15%, w/w) and oil palm empty fruit bunch (20%, w/w) were mixed with soil (500 g) spiked with Tapis crude oil (3%, v/w). The treated soils as well as controls were incubated for 20 days under controlled conditions. Sampling was carried out every four days to measure the number of bacterial colonies (CFU/g) and to determine the percentage of oil degradation by gas chromatography. The two biostimulating agents were able to maintain the soil moisture holding capacity, pH, and temperature at 38-40% volumetric moisture content (VMC), 7.0, and 29–30°C; respectively. The growth of bacteria consortium after 20 days in the treatment with sugarcane bagasse and oil palm empty fruit bunch had increased to 10.3 CFU/g and 9.5 CFU/g, respectively. The percentage of hydrocarbon degradation was higher in the soil amended with sugarcane bagasse (100%) when compared to that of oil palm empty fruit bunch (97%) after 20 days. Our results demonstrated the potential of sugarcane bagasse and oil palm empty fruit bunch as good substrates for enhanced bioremediation of soil contaminated with petroleum crude oil.