Bioremediation Of Hydrocarbon Contaminated Soil Using Selected Organic Wastes
Contamination of existing and potential agricultural lands is a major problem associated with the processing and distribution of crude and refined petroleum products in many oil producing countries like Nigeria. Hydrocarbon contaminants in soil are potentially phytotoxic to plants and interfere with plant establishment and growth as well as other land uses. The problems of pollution have led to the exploration of many remedial approaches to effect the clean-up of the polluted soils. The specific objectives of the study are; to apply food waste, palm oil mill sludge and poultry droppings at different rates of 10, 20 and 30 % (w/w) in soils of simulated diesel contaminated soils; and to determine the effect on petroleum hydrocarbon fractions, soil nutrient composition, and on the total petroleum hydrocarbon (TPH) reduction. From the results of the study, C15 to C41 hydrocarbon fractions including pristane and phytane were detected in the diesel contaminated soil samples. The longer chain hydrocarbon fractions appeared dominant in the contaminated soil samples and were observed to be degraded more at the 20 % (w/w) bio-waste amendment level for all the bio-waste amended soil samples. The hydrocarbon fractions generally reduced with increase in the amount of the bio-waste present in the contaminated samples. The organic carbon and organic matter generally decreased with the increased addition of the bio-waste in the contaminated soil from 10 to 30 % (w/w) however no clear trend was observed for the nitrogen, potassium and phosphorus present in the amended soil samples. After 84 days period of bioremediation process, the TPH in the diesel contaminated soil samples remediated using food waste, palm oil sludge and poultry droppings were observed to have reduced from 27479.43 ppm recorded in the control sample to 17197.79, 19210.64 and 14117.69 ppm, respectively. The resulting percentage reduction in the TPH for the food waste bio-remediated soil sample was 37.42 % while that of the soils remediated using palm oil sludge and poultry droppings were 30.09 and 48.62 % respectively. The result showed that poultry droppings had the highest biodegradation effect followed by food waste and palm oil sludge.