Construction Of Salt-Tolerant Petroleum-Degrading Microbiol Consortium And Degradation Performance

As the oil demand has increased,so water injection development has become an important technology for increasing and stabilizing oil fields in China.At the same time,a large amount of oily wastewater has also been generated.Reinjection of oily wastewater is the best way out.Oily wastewater treatment technologies mainly include physical and chemical methods,biological methods,and membrane treatment methods.Among them,biological methods have the advantages of low cost,easy operation,and no secondary pollution and it is the most promising treatment technologies in oily wastewater treatment technology.However,the high salt content in oily sewage makes it difficult for conventional microorganisms to adapt,which has affected its application in oily sewage treatment to a certain extent.The selection of salt-tolerant microbial strains and their combinations is the key to the large-scale application of microbial treatment of oily wastewater.This article takes simulated oily sewage as the research object,and uses the five strains of bacteria isolated and screened by the research team in the early stage.Using the degradation rate of crude oil as an indicator to screen the best combination strains,domesticate them for salt tolerance,explore their salt-tolerant performance,and determine the optimal environmental conditions for the degradation of crude oil.At the same time,the effects of external substances on degradation performance were studied in order to build a highly efficient petroleum-degrading flora.The main conclusions are as follows:1.By determining the oil-degradation rates of Stenotrop Homonas(A),Pseudomonas aeruginosa(B),Microbacterium oxydans(C),Ochrobactrum intermedium(D),Brevibacillus laterosporus(E)and their re-combination,the comparison results showed oil-degradation rates could reach 74.16%after mixing Pseudomonas aeruginosa,Microbacter oxidans and Ochrobactrum intermedium.2.Among the above five strains and mixed bacteria(B+C+D),Stenotrop Homonas and Ochrobactrum intermedium can only degrade some alkanes,Pseudomonas aeruginosa,Microbacterium oxidans and Brevibacillus laterosporus have obvious degradation effect on all saturated hydrocarbons.The highest degradation rate of alkanes by Pseudomonas aeruginosa was 74.32%,and the degradation effect of Ochrobactrum intermedium on colloid and asphaltene was the best,which were 32.89%and 9.01%respectively.When the three strains of B,C and D were mixed,the strains tended to cooperate with each other.3.Making Pseudomonas aeruginosa,Microbacter oxidans and Ochrobactrum intermedium.be salt-tolerant and acclimated respectively.When the salt content was increased from lOg/L to 50g/L,the growth activity of the three strains was significantly reduced,the biosurfactant production performance was weakened,and the cell membrane permeability was increased.Scanning electron microscopy and transmission electron microscopy analysis showed that the increase in salt content in water increased the loss of water in microbial cells,wrinkles and dents appeared on the surface,cell walls became thinner,and cytoplasm decreased,which seriously affected cell viability.4.After the three strains of salt-tolerant domestication were mixed,the NaCl content was 30g/L,the temperature was 35?,pH=7,the inoculation ratio was 2:2:1,the inoculation amount was 3ml,and the initial crude oil content was 2g/L.When the type of nitrogen source is NH4NO3,the degradation rate of crude oil after8 days is 74.28%;the mixed bacteria emulsify and disperse the crude oil into uniform small oil droplets through the secreted surfactant,which is beneficial to improve the degradation rate of crude oil by mixed bacteria.5.500mg/L glucose and 1 CMC APG was added can increase the biodegradability of crude oil to 81.02%and 86.42%,respectively.Betaine was added can improve the salt tolerance of petroleum-degrading bacteria,and allow the mixed bacteria to grow under the condition that the content of NaCl is 60g/L.Adding betaine,glucose or APG under the same salinity will help improve the oil-degradation rate of salt-resistant petroleum-degrading bacteria.