Bioavailability and bioremediation of diesel fuel-contaminated soil using organic wastes as supplement

Soil and surface water contamination by organic compounds is a common occurrence in most developing countries. This caused harmful effects on the environment and human beings. Bioremediation can be an alternative green technology for remediation of such hydrocarbon-contaminated soil. Bioremediation of soil contaminated with 5% and 10% (w/w) diesel fuel amended with 10% soy cake (SC), potato skin (PS) and tea leaf (TL) was studied for a period of 84 days, under laboratory condition. At the end of 84 days, the highest percentage of oil biodegradation (88%) was recorded in soil contaminated with 5% diesel fuel and amended with SC, while only 75% of oil biodegradation was recorded in soil contaminated with 10% diesel fuel and amended with SC. Bioavailability which was assessed by the hydroxypropyl cyclodextrin (HPCD) extraction method showed that bioavailability reduced in soil amended with organic wastes. Results of first order kinetic model to determine the rate of biodegradation of diesel fuel revealed that soil amended with SC recorded the highest kinetic rate of oil biodegradation 0.148 day and 0.103 day in 5% and 10% oil pollution. The results of this study demonstrated the potential of SC as a good substrate to enhance remediation of hydrocarbon contaminated soil at low pollution concentration.