Study On Bioremediation Mode Of Saline Soil Contaminated By Petroleum

Under the dual stress of salinity and petroleum, the matter of bioremediation of saline soil contaminated by petroleum is more complex and difficult than matter of bioremediation of the soil only contaminated by petroleum,and factors affecting bioremediation effect of soil is more, therefore a single measure of bioremediation is generally difficult to achieve the desire effect.Seeking the appropriate bioremediation mode is necessary in the actual process of bioremediation of soil. At the same time, the appropriate bioremediation mode needs to be efficient, simple, and practical on the condition of field due to differences between interior and field condition.In this paper, the immobilized bacterial is prepared by the oil-degrading bacteria flora screened,consequently the quantity of immobilized bacterial and C: N: P which are appropriate for degradation are achieved and will be applied into the study of bioremediation mode in the field by the study of the effect of C:N:P and the quantity of immobilized bacterial on degradation rate and amount of microbe on the condition that exogenous immobilized bacterial is applied into the soil environment. In order to build an appropriate bioremediation mode, the impacts of kinds of plant and the quantity of fertilizer applied,tillage on the degradation rate were studied on the condition that Alfalfa and indigenous plant of DagangSuaeda are tested plants.We can draw the following conclusions:①Oil-degrading microorganisms which play the strengthened role are subject to bioremediation and the plant can stimulate the oil-degrading microbe to strengthen degradation when the salinity soil contaminated by petroleum is bioremediated interior and in the field.The microbial characteristics of immobilized bacterial determines the level of degradation rate, long-term preserved immobilized bacterial or fertilizer which is prepared by the long-term preserved bacteria will degenerate and influence the bioremediation effect.So this kind of immobilized bacterial can not be used into application.②C: N: P is an important factor affecting the degradation of pollutants, too high or too low is not appropriate for the degradation of oil pollutants in the process of bioremediation of soil. Increasement of the quantity of immobilized bacterial will increase the degradation rate,but higher quantity of fertilizer does not make a significant increase in the degradation rate and degradation rate will be falled instead of rising trending in the higher C: N: P. In this study, the appropriate C: N: P for bioremediation of saline soil contaminated by petroleum is100: 5: 3, correspondly the appropriate quantity of immobilized bacterial is 10%.③The study of bioremediation mode in the field indicates that the tillage can improve effect of bioremediation of oil to some extent in the disturbed soil, but the improvement is not more than 2% which can be ignored. But effect of tillage needs to be further studied in the non-disturbed soil.④Indigenous advantage salinity plant-Suaeda shows the better adaptive faculty than alfalfa in terms of germination and growth conditions under double stress of contaminated soil in Dagang.Under the same conditions,the degradation rate of soil contaminated by petroleum planting Suaeda is also significantly higher than alfalfa.⑤In the condition that the immobilized bacterial prepared is applied in the appropriate nutrition and 17000 mg / kg of salinity soil contaminated by petroleum,the degradation rate reaches a larger value quickly in the twenty days after the immobilized bacterial was applied,then degradation rate is in the relatively stable state and the degradation rate can reach48.97% and 52.39%.interior with non- plants and field condition planting Suaeda.⑥The appropriate bioremediation mode in the field is plant- microorganism jointed strengthen combination with nutrition stimulation under the condition that salinity of soil is4000mg/kg, petroleum is 17000 mg / kg.Specific measures is that 10% of the fresh salinity immobilized bacterial is applied to the soil with planting Suaeda and non-tillage, guaranting nutrient is 100: 5: 3(C: N: P).