A Comparative Study on the Bioremediation of Spent Engine Oil Contaminated Soil Using Cow Dung, Poultry Manure and Saw Dust

The contamination of the soil with spent engine oil has become a threat on the health of the public as hazardous chemicals are released into the environment. In this study, three organic wastes (cow dung (CD), poultry droppings (PD) and saw dust (SD)) were used for bioremediation of spent engine oil contaminated soil to determine the potential of these organic wastes in enhancing biodegradation of spent engine oil in the soil. This research was undertaken in eight phases. These wastes were added to the spent engine oil contaminated soil individually and in combination (SD ONLY, CD ONLY, PD ONLY, CD+SD, PD+CD, SD+PD, CD+SD+PD) and oil contaminated soil only as control. The rates of bioremediation of the spent engine oil was studied for a period of 8 weeks under laboratory conditions. Physicochemical analysis, isolation and enumeration of bacteria and fungi were done. Characterization and identification tests of isolates revealed that a microbial consortium comprising of the following Hydrocarbon Utilizing Bacteria genera; Bacillus subtilis, Pseudomonas aeriginosa, Proteus vulgaris, and Klebsiella aerogenes Similarly, the Hydrocarbon Utilizing Fungi encountered were Aspergillus niger, Aspergillus flavus and Mucor sp. Hydrocarbon-utilizing bacterial and fungal counts were high in all the organic waste-amended soil when compared to unamended control soil throughout the 8 weeks of study. Spent engine oil-contaminated soil amended with a combination of cow dung and poultry manure as biostimulant showed the highest spent engine oil loss in 8 weeks compared to other treatments. These results revealed that a combination of poultry manure and cow dung was the best of the organic wastes used. The results obtained demonstrated the potential of organic wastes for oil bioremediation in the order PM+CD>PM>CD>PM+SD>SD+PM+CD >CD+SD >SD. Hence, all the biostimulants showed the ability to stimulate the growth of microorganisms for used engine oil degradation.