| The demulsifying mechanism of microbial demulsifying strain TR-1 and its application on the oilfield produced water treatment system were studied in this thesis. The study mainly included: (1) Identification of de-mulsifying strain TR-1. (2) Analysis on the demulsifying pathway of strain TR-1. (3) Isolation, purification and identification of biosurfactants produing by strain TR-1. (4) Effect of the application of de-mulsifiers on the treatment system of oilfield produced water. The experiment results showed that: (1) With VITEK2 compact system, homology analysis of 16S rDNA sequences and traditional biochemical and physiological experiment, TR-1 was identified as an Alcaligenes species. (2) The demulsification capabilities of TR-1 were mainly due to some biosurfactants, which was produced during the culture course of TR-1. The biosurfactants were tightly combined with cell wall and made the surface tension of the whole culture broth from 56.3mN/m to about 29.0mN/m. Furthermore, their demulsification capabilities couldn't be destroyed by drying and sonic dismembration. (3) It was feasible to isolate the biosurfactants from the surface of TR-1 drying powders by using organic solvent extraction. It was preferred to use chloroform-methanol (2:1, V/V) as extraction solvent. The ratio of the drying powders weight to the solvent volume was better to choose 0.1g/150mL (6.67×10-4g/mL) and 12 hours was the optimum extraction time. (4) Characterized by thin layer chromatography and fourier transform infrared spectrometry, the biosurfactants producing by TR-1 was identified as one kind of lipopeptide. (5) The experiment results showed that the application of TR-1 microbial demulsifiers on the treatment system of oilfield produced water didn't have any bad effects. Instead, it could obviously reduce the COD of the separated water, which could help the effluent satisfy the exhaust standard. In terms of reinjection system, the separated water using microbial demulsifiers had lower uniform corrosion rate, less TGB number and slower barium sulfate scaling tendency. In a word, it increased the safety degree of reinjection water.
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