| Oily sludge is the waste produced in the process of petroleum exploitation and smelting.There are toxic and harmful substances in oily sludge,so it is listed in the National List of Hazardous Wastes and is the pollution source in the petroleum industry.In this paper,the oily sludge of Karamay oilfield in Xinjiang was taken as the research object,and 15 native herbaceous plants were screened for tolerance,and 4 herbaceous plants with high tolerance were obtained.Then,four plants and microorganisms were combined for a pot experiment for 120 days.The contents of petroleum hydrocarbon,plant biomass,total chlorophyll,malondialdehyde and rhizosphere microorganisms in soil were monitored,the best combination mode of plants and microorganisms was selected,and clarify the repair mechanism.The specific research results are as follows:1.The relative germination rates of Festuca elata,Lolium perenne,Sorghum sudanense and Cynodon dactylon can reach more than 73.68%,when the sludge concentration is 50 g·kg-1,which is significantly higher than CK group without pollution.The plant height,biomass,root system and root surface area of the four plants were all inhibited,and there was no significant difference.At the same time,the four plants had higher sludge degradation capacity,reaching 26.23%,35.21%,30.10%and 35.21%respectively,which was 1.86 times,2.50 times,2.14 times and 2.43times that of CK group.2.The results of pot experiment showed that Sorghum sudanense,Cynodon dactylon,Bacillus subtilis and Bacillus subtilis had similar restoration effects,which were higher than CK group by 33.66%,35.21%,34.29%and 33.66%respectively.When combined,Cynodon dactylon had better effects with bacteria A,B and C,respectively,and the degradation rates reached 43.02%,40.20%and 42.54%,which were significantly higher than CK group’s 48.73%,44.90%and47.93%.The number of cultivable bacteria and fungi in soil increased significantly after combined treatment,which was higher than that of single treatment group.Among them,Cynodon dactylon,Festuca elata and Sorghum sudanense were added with four degrading bacteria,and the fresh weight,chlorophyll content and malondialdehyde content of plants were all increased.3.The results of high-throughput sequencing showed that the dominant phylum and genus of bacteria and fungi after plant,microorganism and plant-microorganism treatment were the same as before treatment.In the phylum level,the phylum with dominant relative abundance is concentrated in Proteobacteria,Actinobacteriota and Planctomycetota;The dominant genera are Salegentibacter,Salinimicrobium and Sphingorhabdus.Ascomycota,Chytridiomycota and Rozellomycota are dominant in relative abundance of fungi,and the dominant genera are concentrated in Ciliophora and Fusarium.The results showed that the efficiency of combined remediation of selected tolerant herbs and microorganisms was significantly higher than that of single treatment,which promoted plant height,biomass and rhizosphere microbial community,etc.,indicating that adding degrading bacteria can be used as a strengthening means for phytoremediation of oily sludge,and provide scientific basis and technical support for biological treatment of local low-concentration oily sludge in Xinjiang,at the same time,it is of great significance for ecological environment restoration in Xinjiang. |
