Study On The Removal Of Cr（Ⅵ） And NO₃-N From Groundwater Aquifer By Nano Emulsion Oil

According to the research on Suzhou mining area and the research status of groundwater pollution at home and abroad,the groundwater in the mining area is facing serious mixed pollution caused by heavy metals,organic matter and inorganic matter.In view of this kind of mixed pollution,there are few reports on the in-situ groundwater remediation methods that can efficiently and stably remove it with low treatment cost.Therefore,it is urgent to find a method to remove the mixed pollution of groundwater efficiently and stably with relatively low cost.Therefore,Cr（Ⅵ）and NO₃-N were selected as pollution removal indexes in this paper to conduct in-depth research on how to stably and efficiently remove the mixed pollution of Cr（Ⅵ）and NO₃-N in groundwater aquifers.It provides a scientific basis for Suzhou mining area and even similar mining area in China to remediation the mixed pollution caused by conventional pollution and heavy metal pollution more efficiently and stably by in-situ remediation technology.The results are as follows:（1）The experiment of the optimal ratio of Nano Emulsified Oil shows that when the internal phase content of Nano Emulsified Oil is 25%,the degradation efficiency of Cr（Ⅵ）and NO₃-N pollution in the environment is the highest.At the same time,the addition of Nano Emulsified Oil will not cause secondary pollution to the groundwater environment.（2）The experiment of the influence of Nano Emulsified Oil on the permeability of the sand box shows that the injection of Nano Emulsified Oil causes a small permeability loss of the aquifer of sand box,The average permeability loss rate of each monitoring site was 8.78%,and will not cause blockage of the aquifer.（3）The change curve of removal rate of Cr（Ⅵ）and NO₃-N pollution shows that the change curve of removal rate of Cr（Ⅵ）and NO₃-N pollution is similar,and Nano Emulsified Oil has preferable removal effect on both kinds of pollution,and the removal efficiency of NO₃-N is slightly higher than that of Cr（Ⅵ）.（4）The results of the comparative analysis on the pollution removal rate of each profile monitoring point show that the pollution removal rate of the monitoring point at theⅡ-Ⅱ’profile are the highest,followed by the other two profiles,and the pollution removal rates of theⅢ-Ⅲ’profile are slightly higher than that of the I-I’profile.In terms of the removal rate of the monitoring points in the upper,middle and lower layers of the three profiles,the removal rate of the monitoring points in the upper layer is the highest,followed by the middle layer and the lower layer.（5）The three-dimensional Effective Removal Zone（ERZ）spatial distribution of Cr（Ⅵ）and NO₃-N shows that under the condition of instantaneous injection,15ml of Nano Emulsified Oil and 500m L of domestication bacterium fluid were added to the injection well every 8 days,a relatively stable ERZ（80）of Cr（Ⅵ）with a volume ratio of 44%can be formed in the sand box,and also can ERZ（85）of NO₃-N with a volume ratio of 45%;Under the condition of continuous injection,Nano Emulsified Oil was injected into the sand box at a rate of 0.1r/min every 23 days,and 1L of domesticated bacterial fluid was injected in the way of instantaneous injection,relatively stable ERZ of Cr（Ⅵ）and NO₃-N could be formed in the homogeneous aquifer around the injection well.When ERZ was filled with the sand box,the removal rates of Cr（Ⅵ）and NO₃-N could reach 93%and 97%,respectively,and the stable time was not less than 3 days.