| Summary: | 博士 === 國立中央大學 === 土木工程研究所 === 88 === A Spill of crude oil at a refinery tankage area contaminated the subsurface soil. The first experiment was once made by putting contaminated soils in a reactor of 20cm in diameter (soil height: 10cm) with air ventilated on the bottom and the moisture content in soil kept to about 18%. This experiment lasted for 175 days, with the result that the TPH(Diesel) content was reduced from 9544mg/kg to 5406mg/kg. The removal rate of 43.4% is not effective. After carefully study and evaluate, biological and electrokinetic process are applied. Results are presented from a field experiment that documented the in-situ cleanup process of crude oil. The enhanced bioremediation was accomplished by stimulating the growth of indigenous bacteria, which transform hydrocarbons by co-metabolic process to carbon dioxide and water. Biostimulation of the test pit was successfully achieved by addition of ammonia, bicarbonate, trisodium phosphate, glucose and hydrogen peroxide within three weeks.
An electro-kinetic method which combined effects of electrophoresis, electro-osmosis, electrolysis and ion exchange, was also applied. Like biological process, the same lot of 12m ×5m ×1m was used. A DC power of 110V was applied. Testing results indicated that electro-kinetic induced a hydraulic gradient that helped most of the lighter hydrocarbons in crude oil be removed from the soil within three weeks. The pH values of 2.5 at anode and 11 at cathode were measured and indicated that the reduction and oxidation process occurred as expected.
In order to fine the better solution to remove the contaminated soil, the electro-kinetic process coupled with biodegrdation was also applied to different concentration of contaminated soil. These results indicated that similar removal efficiency achieved within two weeks and the combined technique may be a better process to clean up the contaminated soil which contained high concentration of hydrocarbon.
It is not easy to find the cleanup technologies in detailed procedure from the published paper , and it seldom happens and applies biological and electrokinetic process to remove crude oil from a contaminated soil. Instead of laboratory experiment, the parameters and results of in-situ test is easy to apply to the on site treatment and remediation. This is the main purpose of this research.
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