Bioremediation of petroleum contaminated soil: An evaluation

In most developing countries, disposal of waste engine oil into the environment is indiscriminately done due to unavailability of proper waste engine oil treatment plants and poor waste management systems. In a bid to clean up contaminated soil with waste engine oil, four bioremediation techniques; natural attenuation, bioaugmentation, mycoremediation and phytoremediation, were evaluated. Waste engine oil contaminated soil samples used for preliminary study were obtained from Suame in Kumasi, Ghana and Orji in Owerri, Nigeria. Three levels of simulated waste engine oil contamination were prepared in a soil-oil mixture ratio using 67.5 ml, 337.5 ml and 675 ml of waste engine oil to 5 kg of top soil, indicated as samples HCSSL1, HCSSL2 and HCSSL3 respectively. The experiment was carried out under aerobic condition with a completely randomised design using four replicates for each level of treatment contamination. The experiments were monitored over twelve (12) months. Cultures of the hydrocarbon utilizing bacteria (Bacillus subtilis) and fungi (Trichoderma spirale) isolated from the contaminated soils were applied to the three levels of contamination.