Monday, May 4, 2009
11-10
Characteristics of biodemulsifier produced by one strain of Alcaligenes sp. S-XJ-1 and its application in emulsion destabilization
Xiang-feng Huang, Jia Liu, and Li-jun Lu. College of Environmental Science & Engineering, State Key Laboratory of Pollution Control and Resource Reuse, Tongji University, Room 115#, Mingjing Building,Tongji University,Siping Road 1239#,Shanghai,China,200092, Shanghai, China
As a kind of biosurfactant, biodemulsifier is highly efficient in breaking industrial emulsions due to their unique functional groups. One biodemulsifier producing strain S-XJ-1 was investigated on its screening methods, its application in model/crude oil emulsion and its effect on the oilfield produced water treatment system. For the identification of efficient demulsifying strains, the proposed screening protocol was set as follows: surface tension level was set at 40 mN/m, then detected strains were further verified in demulsification test. By this screening protocol, one strain named S-XJ-1, was isolated from petroleum-contaminated soil and identified as Alcaligenes sp. by 16S rRNA gene which proved no toxicity by little mouse test. It achieved 96.5% and 49.8% of emulsion breaking ratio in W/O and O/W kerosene emulsion within 24h, respectively. It also showed 93% de-emulsifying efficiency in 150min in W/O Kelamayi crude oil emulsion. S-XJ-1 showed stable demulsifying ability at pH from 3 to 11 while chemical demulsifier doesn’t work when pH was 3. Results of its influence on oilfield produced water treatment system showed that the effluent treated by the biological demulsifier had lower COD but higher SS concentrations than that by the chemical demulsifier. In terms of the effluent system, COD in the effluent from coagulation/filtration process was 350mg/L after dehydration by chemical demulsifier. Compared with that, COD was reduced to 150mg/L by biodemulsifier. In terms of reinjection system, the effluent from biodemulsifier treatment had no scaling tendency of SrSO4 and very lower coupon corrosion rate than the effluent by chemical demulsifier.