Two bacterial strains, paraffin removal strain and biosurfactant-producing strain, named BHJ-1 and QFL-1, were isolated from oil production wells in Daqing oilfield of China. They were subsequently identified as Bacillus cereus QAU68 and Bacillus subtilis XCCX, respectively. As an indicator of the degradation paraffin, the inoculum concentration of BHJ-1 and QFL-1 were added in different proportions, the optimum proportion was 5:2. In this proportion the degradation rate of paraffin could reach 64 %, the prevention rate of paraffin could reach 55 %.Keywords Paraffin Á Bacillus cereus Á Bacillus subtilis Á Degradation Microbial treatment method of paraffin deposition has been used as a sustainable replacement to conventional treatment methods (chemical, mechanical and thermal methods) [1,2]. Industrial scale tests were accomplished in Jidong, Daqing, Liaohe and Zhongyuan oilfields in China [3], but there is no large-scale application by microbial treatment on the whole, the reasons for restricting the large-scale application are short of validity period and less efficiency. Adding special biosurfactant can lower the interfacial tension as their primary activity [4,5], increase the hydrocarbon concentration in the water [6,7], therefore adding the special biosurfactant may be propitious for combination of crude oil and bacterial liquid, prolong the validity period, increase the efficiency of microbial treatment and paraffin deposition.During this study two isolates, paraffin removal strain and biosurfactant-producing strain, named BHJ-1 and QFL-1, were isolated from oil production wells in Daqing Oilfield of China. BHJ-1 was isolated from enrichment salts medium (ESM) containing 0.5 % (w/v) of crude oil. The system was operated at the following parameters: temperature 37°C, pH 7.2, incubation period 7 days. In order to isolate oil-utilizing microorganisms, 0.1 ml of culture supernatant was transferred every 24 h onto nutrient agar plates [8]. QFL-1 was isolated from ESM and it was cultivated at orbital shaking (180 rpm) at 37°C for 72 h. The culture fluid was spread on the cetyl tri ammonium bromide-methylene blue agar medium and cultivated at 37°C for 9 days. Then, the colonies of the halo were extracted, streaked on crude oil agar medium and cultivated at 37°C for 9 days. After five times plate streak, the pure strains could be purified [9]. The isolates were stored in isosensitest broth at 4°C and were plated in Isosensitest agar for further investigation [10]. The photo of scanning electron microscope is shown in Fig. 1. Phylogenetic tree was constructed and analysis was done by neighbour joining method through MEGA 5 software (Fig. 2). Partial sequencing with both primers revealed that the closest matches, determined by a BLAST search, corresponded to Bacillus cereus QAU68 (99 % similarity, BHJ-1) and Bacillus subtilis XCCX (99 % similarity, QFL-1), respectively [11,12].As an indicator of the degradation of paraffin, BHJ-1 and QFL-1 were added in different proportions. The
The aim of the study was to increase the production of biosurfactant by using the inexpensive medium materials and the optimized fermentation conditions. Five biosurfactant producers were isolated from oilfield wastewater. The most efficient strain S2 was identified through 16S rDNA sequence analysis, which exhibitted the highest similarities to Bacillus subtilis strains CCTCC M201162. The optimal medium composition of this strain were beer wastewater 40 g/L, diammonium phosphate (NH 4 H 2 PO 4 ) 4 g/L, MgSO 4 0.02 g/L, NaCl 5 g/L. The emulsification index (E 24 ) was optimized using a box-behnken experimental design and response surface methodology(RSM). The RSM revealed that when pH was 7.2, temperature was 42.1 C, inoculum concentration was 5.2% (v/v) and rotate speed was 163 r/min, the optimal condition was obtained. Under this condition, the optimal E 24 of the biosurfactant produced by Bacillus subtilis strains CCTCC M201162 was 81.20%, the production of crude biosurfactant increased from 0.72 g/L to 1.26 g/L and the surface tension of fermentation broth reduced from 72.0 mN/m to 22.8 mN/m. A quadratic response model was constructed through RSM designs, leading to a 75.0% increase of biosurfactant production by Bacillus subtilis strains CCTCC
By separation and purification experiment, microorganisms were obtained. The paraffin removal strain was named for SW-1. Microscopic and morphological examinations showed strain SW-1 was to be Bacillus Cereus. After strain SW-1 treatment, the number of strain SW-1 increased from 2.7×106/mL-1to 3.5×108/mL-1, which increased by two orders of magnitude; the degradation rate of paraffin could reach to 64% within one month; the prevention rate of paraffin could reach to 43%; the viscosity of crude oil reduced from 35.9mPa•s to 26.8mPa•s, the reduction rate of viscosity was 25.3%, and the freezing point of crude oil reduced by 4.3°C; surface tension reduced from 44.5mN•m-1to 29.1mN•m-1, the reduction rate of surface tension was 34.6%, and pH value was reduced to 6.3. These phenomenon indicated that strain SW-1 has better removal paraffins effect.
The novel soft magnetic materials and magnetic core structure used in planar transformer have been studied. The frequency, electrical and structure feature of the planar transformer with matrix structure was described. Then the novel magnetic materials used in the planar transformer were discussed, which were very different from ferrite block. The silicon steel strip was first represented, the magnetic characteristic of which was related to its geometric dimension, working frequency and the component. The microcrystallite alloy and amorphous alloy magnetic materials were then indicated, including iron-base nanocrystal and cobalt-base amorphous alloy. The magnetic materials of the above amorphous alloy and microcrystallite alloy were compared respectively. These soft magnetic materials could be used as the magnetic core in planar transformer, and the magnetic core could be composed of thin strip and line. The structure of magnetic core was flexible, which could benefit the planar transformer to reduce its volume. The development and trendy of novel magnetic materials and magnetic core in planar transformer were analyzed and discussed in this paper.
The degradation law of straw lignin by white-rot fungi was studied. The adding amount of synthetic medium, the inoculum size and the temperature were investigated by experiment of single factor and orthogonal experiments. In the 6.5g straw fermentation medium, the optimum process conditions of degrading straw lignin by white-rot fungi were as follows: the adding amount of synthetic medium was 14mL; the inoculum size was 0.8mL; the temperature was 35°C. Through the additional experiment, degradation rate of the lignin was 49.50%; the degradation rates of cellulose and hemicellulose were 38.41% and 47.88%, respectively.
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