| Oil pollution has always been an important problem affecting the soil environment safety in oil field, and it is also a hot issue at home and abroad.The soil in the oil area of our country, also faces serious problems of salinization, which not only has greatly increased the difficulty of remediation, but also makes the traditional bioremediation insufficient.Electro-bioremediation is a new technology which has been developed in recent years. It has achieved good results in the remediation of conventional oil-contaminated soil.The aim of our work is to study the feasibility of this technology to restore oil contaminated saline soil.This paper takes the saline soil without oil contamination from Shandong Dong Ying island in the Yellow River Delta area as the research object, artificially spiked with oil of 2%,to represent the actual contaminated soil.Research work is mainly divided into three parts.Firstly, study the influence of electric technology on the physical and chemical properties of soil, and determine the appropriate experimental conditions.Then, using the soil in the electric field as the base soil, select and identify strains of high oil degrading efficiency.In the end, combine electric technology and the oil-degrading bacteria selected and study the effect and feasibility of this associated technology.Through the research work, the ideal repair effect is obtained. The main conclusions are as follows:(1)Two power modes were used, one was constant direct current and the other was capable to reverse the polarity of the electric field per hour.It was found that in the former electric field,the soil pH close to the anode could be 2;otherwise,soil near the cathode rose to 13.Whereas by reversing the polarity at intervals, the soil pH was well maintained at neutral levels. In addition, the insertion of the electrodes, caused the increase of soil temperature which, to a certain extent, can improve microbial activity.Also it led to the loss of soil moisture, and needed to regularly add soil moisture.In a word, reversing the polarity of the electrode was the suitable experimental conditions.(2)Through the separation, purification and oil degradation experiment, two kinds of highly effective oil degrading strains were obtained. By adding 10% bacteria liquid to the crude oil medium,the oil degradation rate could reach 20% after one week.By morphological observation, 16 Sr RNA sequence analysis and physiological-biochemical experiments, it was identified that the two stains were Escherichia coli and Bacillus cereus respectively which had a tolerance of electricity and salt.(3)After eighty-day respiration experiment,Electro-bioremediation technology could reach an oil degradation rate of more than 28%.The degradation effect was even more obvious near the electrode area with a 35% oil degradation rate. However the degradation efficiency of Bioremediation and Electro-remediation were 15% and 22% respectively. The Electric technology had not change the oil degradation sequence, that the saturated hydrocarbon and aromatic hydrocarbon were much more easier to be degraded than colloid and asphaltene. However the electric field had a certain role in promoting the degradation of the last two components. During the experiment, it was necessary to supplement the soil moisture in order to maintain a higher electric intensity.(4)The technology of Electro-bioremediation on the oil contaminated saline soil is feasible with a low cost and obvious effect and convenient management.After the energy consumption analysis, it consumed about 4.84kw·h power per kilogram soil during the total experimental process of Electro-bioremediation, whose cost was relatively low. |
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