Sequential Remediation Processes for Effective Removal of Oil from Contaminated Soils

Abstract

Problem statement: Over 2.2 billions of oil and oil products were transported every year and often these activities can result in air, water and soil contamination. Expousure to petroleum products can cause health problems to humn and animals and affect marine animals and wildlife habitats. Approach: The objective of this study was to developed a technology for the remediation of soil contaminated with petroleum hydrocarbons. The remediation method included three processes: (a) an effective soil washing process for the removal of the hydrocarbons from the contaminated soil, (b) an efficient water decontamination process using peat moss as an oil absorbent and (c) an effective bioremediation process for converting the oil in peat moss into carbon dioxide and water. Results: The results showed that water was an effective solvent for the removal of oil from contaminated soil. It had also been determined that peat moss is an effective absorbent and could be used to remove oil from the contaminated water. Peat can absorb 12.6 times its weight liquid (water/oil). The bioremediation process was effective in degrading the oil into harmless carbon dioxide and water products. About 77.65% of the THC was removed within 60 days of bioremediation. The hemophilic microbial population in the compost quickly acclimatized to the hydrocarbon as was evident from the immediate rise in the reactor temperature. The C: N ratio decreased from 30:1-12:1 indicating the degradation of organic C in the petroleum hydrocarbons and the peat. Urea was a very effective source of nitrogen in initiating and maintaining intense microbial respiration activity. Conclusion: A sequential processes for the remediation of oil contaminated soil is developed. These included soil washing, absorption of oil from water using peat and bioremediation of contaminated peat. A degradation model is developed and used to calculate the time required for a complete degradation. The model indicated that a total degradation of oil could be achieved within 68.5 days.