Isolation And Characterization Of Compound Pollutant Degrading Bacteria From Polymer-sulphated Drilling Slurry

In this study, polymer-sulphated waste drilling slurry sample collected from different drilling well in Sichuan was used to isolate waste drilling slurry degrading bacteria by pour plate method, and 10 bacterial strains were obtained, and named JH1-JH10; strain JH2 was coccus, and the other strains were bacillus; the physiological and biochemical aspects and classification status and ability to degrading drilling slurry was determined. The results were as following.The physiological and biochemical test results showed that, the optimal growth pH of strain JH3 was 7.0, and its optimal growth temperature was 37℃; While, the optimal growth pH of the other strains were 9.0, and the optimal growth temperature was 28℃. The tested strains had high alkali tolerance and salt tolerance; however, these strains had very narrow carbon and nitrogen source utilization ability.All strains were able to use polymer-sulphated drilling slurry as sole carbon source, and the more drilling slurry adding into medium, better the strains grew. In order to determine the relationships between bacterial count and adding quantity of drilling slurry, selecting JH2 as the representative strains to determine its colony number in liquid culture medium adding different quantity of drilling slurry, results showed that, when the adding amount of drilling slurry was 50g/L, the strain had the largest number, reached 9.20×108 cfu/mL.In order to determine the classification status of the strains further, they were identified at the molecular level.16S rDNA phylogenetic tree was constructed using the P1, P6 as primers. The results showed that, strain JH1, JH8, JH9, JH10 and B. halodurans DSM497T located on the same phylogenetic branch, the strain JH8 and JH9 were 100% B. halodurans DSM497T; JH2 had the highest sequence similarity with S. qinghaiensis YIM 70212T, reached 99.2%; JH3 had the highest sequence similarity with Be. pelovolcani CC-SAL-25T, reached 98%; JH4 and JH6 located in the same phylogenetic branch with H. ventosae A112T, JH6 was 98.8% homology with H. ventosae A112T.The strains were inoculated in to 60 ml polymer-sulphated drilling slurry culture with 3%(V/V) of the inoculation, determining the changes of COD value and diesel content, combined with the 16S rDNA sequence results, five high degrading strains were screened, JH2, JH3, JH4, JH6 and JH9, and used for the next experiment of influence factors analysis.Then, the ability of dominant strains degrading the pollutant in different inoculation quantity and different initial pH was researched, the results showed that:the effect degrading the pollutant of strains in the 3% inoculation is better than that of inoculation was 1% and 5% on the COD value and content of diesel; It is better in the natural pH than adjusting the initial pH to 7 on COD value, chroma and diesel oil content.Finally, the change of main anion’s concentration was studied in the process of JH2 degrading the polymer-sulphated drilling slurry, the results showed that, the concentrations of Cl-, NO3- and SO42- were increased gradually in the process, and the effect of mixed strains was better than JH2.