Study On The Mechanism Of Pseudomonas Sp.SWP-4 Bacteria And Its Products On The Prevention And Control Of Biological Corrosion Of The Reinjection Water Pipeline

In this paper,the corrosion and corrosion mechanism of water injection pipelines carbon steel Q235 induced by Pseudomonas sp.SWP-4,which have been proved that Pseudomonas sp.SWP-4 can improve the oil recovery by the degradation of waste cooking oil in our previous study,were studied by the static weight loss and electrochemical experiments and the characterization methods,such as SEM and EDS,in the whole growth period of Pseudomonas sp.SWP-4.And the corrosion inhibition of the fermentation broth to Q235 carbon steel were investigated.Meanwhile,for the microbiologically influenced corrosion of water injection pipelines caused by other microorganisms,the antibacterial activity of the fermentation broth to main harmful microbial sulfate reduction bacteria(SRB)were researched.Moreover,the corrosion inhibition mechanism of water injection pipelines was further investigated when the fermentation broth were added to the produced water.The results showed that the metabolism of Pseudomonas sp.SWP-4 had an influence on the chemical states of medium,which is ascribed to the rapid accumulation of rhamnolipid produced by Pseudomonas sp.SWP-4 in the plateau.And it also can be found that the pH of the solution medium gradually increased to 7.2 in the growth metabolism of Pseudomonas sp.SWP-4.The experimental results showed that the corrosion caused by Pseudomonas sp.SWP-4 is fairly slight within a growth cycle.And the corrosion of water injection pipeline steel was promoted by the bacteria in the exponential phase,in which the metabolism of the bacteria is the most vigorous,which was mainly attributed that the halophilism of Pseudomonas sp.SWP-4 adsorbed on the surface of the carbon steel led to the increase of anion depolarizing agent concentration,such as Cl-.After Pseudomonas sp.SWP-4 entered the plateau,the biosurfactant rhamnolipid was accumulated rapidly and the corrosion current density is much smaller than the blank control group,which is mainly due to the corrosion inhibition of biosurfactant rhamnolipid.By the study of the static weight loss and electrochemical polarization experiments of carbon steel specimen immersed in the centrifuged fermentation broth,it can be found that the fermentation broth didn’t cause the corrosion of carbon steel and the biosurfactant rhamnolipid even can inhibit corrosion.So the corrosion rate is lower than the carbon steels soaked in the sterile deionized water.SEM also further indicated that the carbon steel immersed in the the centrifuged fermentation broth was more intact than that soaked in the sterile deionized water.In addition,the research results also indicated that SRB in reinjection water can promote corrosion especially at exponential stage.And the corrosion can be weakened at the stationary phases.But at the same time,H2S was produced due to the metabolism of SRB so that the corrosion also can be further promoted due to the existence of H2S.However,when the fermentation broth containing different concentrations of rhamnolipid was added to reinjection water,the fermentation broth can inhibit corrosion due to its adsorption resistance and antibacterial activity.