| This study takes an iron-based tailings in Guyang County,Baotou City as the object,and uses microbial enhanced municipal sludge soil forming technology to carry out the ecological restoration of iron-based tailings.The experiment is divided into four parts:pioneer plant screening,bacterial agent application ratio,pot improvement experiment and field demonstration.Finally,the data are measured and analyzed,and the experimental effect is remarkable and the expected experimental purpose is achieved.The main conclusions are as follows:(1)In In view of the problems of high salinity,low nutrition,poor water retention and difficult effective utilization of iron-based tailings,according to the literature and on-site environmental investigation,this study selected the pioneer plants suitable for iron-based tailings environment,including alfalfa,blue fescue and Caragana korshinskii;The bacterial agents selected in the experiment were Bacillus glialis(J),Azotobacter rotundum(H),Bacillus megaterium(D)and Bacillus mengkeyou(B).(2)According to the selected plants and bacterial agents,a total of 11 treatment groups and a control group were set up in the pot improvement experiment.A total of 12experimental groups were set up.The experiment lasted for 3 months.At the end of the experiment,the measurement and collection of experimental data were completed.After treatment,the plant height of the plant treatment group increased significantly.Compared with the control group,the average stem height of Alfalfa increased by 63.99%,the average stem height of blue fescue increased by 36.32%,and the average stem height of Caragana increased by 57.23%;The plant roots in the plant root treatment group were more developed and strong.The content of proline in plants decreased.The lowest content of Alfalfa in BD group was 26.42 ug/g,and the lowest content of blue fescue in BD group was 9.39 ug/g.The p H of tailings decreased most obviously in alfalfa,and the p H of jbh group decreased the best by 8.02,which was 0.88 units lower than that of the original tailings;The urease activity of tailings accumulated significantly in alfalfa and blue fescue,and the contents of alfalfa and blue fescue were the highest in JH group.The experimental group of Alfalfa with better repair was selected for microbial analysis.At the phylum level,the abundance of TM7 bacteria in JH group was more prominent,which was 21.54%,significantly higher than that in other treatment groups;The abundance of Nitrospirae was increased in the treatment group,which was about twice that of CK group.At the genus level,the abundance of Thiobacillus was 7.1%in CK group and decreased to 1.4%～2.7%in treatment group.The growth condition of Alfalfa in tailings is the best among the three plants.The repair effect of treatment group BD group,JBH group and JH group is more significant.(3)The site is located in a waste iron-based tailings in Guyang County,Baotou City,with an experimental area of 30 m×40 m,14 groups were set up in the experiment,including bacterial agent group,mixed application group,matrix group and control group.The demonstration lasted for 60 days.At the end of the demonstration,the experimental data were collected.The results showed that the biomass of the treatment group added with municipal sludge and bacterial agent was 2.5 times higher than that of the control group,and the coverage of mengkeyou bacteria+round brown nitrogen fixing bacteria+municipal sludge treatment group(group I)reached 89.0%,which was 64.0%higher than that of CK group.In terms of physical and chemical properties of tailings,the p H of the treatment group decreased by 6.02%on average,of which the p H of group I was 8.2,which was 8.28%lower than that of the original tailings;The water content of tailings has been significantly improved.The water content of group C,group F and group I added with mengkeyou bacteria has been increased to 12.98%,10.12%and 12.08%respectively.The treatment group has been significantly improved in terms of available nutrients.In terms of microbial community,at the phylum level,Bacteroidetes,which can promote plant growth,increased in the treatment group,and increased significantly in group Y,increased by 15.84%;Actinobacteria and Acidobacteria decreased in the treatment group.At the genus level,the relative abundance of Pseudomonas in the treatment group was higher than that in CK group;The relative abundance of devosia and Bacillus increased in the treatment group.(4)The project cost of the demonstration project is calculated.The cost of using the remediation technology in this study is 15.95 yuan/m~2,and the remediation technology of covering soil with traditional tailings is about 18 yuan/m~2.For Inner Mongolia,the remediation cost of tailings is higher due to the thin thickness of soil layer.Using this demonstration technology to repair tailings can reduce the cost investment by 11.39%,and the demonstration technology has popularization value. |
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