Enhanced Biodegradation of Hydrocarbons in Soil by Microbial Biosurfactant, Sophorolipid

Effectiveness of a microbial biosurfactant, sophorolipid, was evaluated in washing and biodegradation of model hydrocarbons and crude oil in soil. Thirty percent of 2-methylnaphthalene was effectively washed and solubilized with 10 g/L of sophorolipid with similar or higher efficiency than that of commercial surfactants. Addition of sophorolipid in soil increased biodegradation of model compounds: 2-methylnaphthalene (95% degradation in 2 days), hexadecane (97%, 6 days), and pristane (85%, 6 days). Also, effective biodegradation method of crude oil in soil was observed by the addition of sophorolipid, resulting in 80% biodegradation of saturates and 72% aromatics in 8 weeks. These results showed the potentials of the microbial biosurfactant, sophorolipid, as an effective surfactant for soil washing and as an in situ biodegradation enhancer.     

原油中多环芳烃内标法指纹分析

建立了用于油指纹鉴别的内标法检测原油中多环芳烃的分析方法.讨论了前处理中层析分离能力,结果表明柱层析分离效果良好,全部多环芳烃组分均进入第二部分洗脱液中;确定了基于谱图特征,结合离子碎片信息和计算保留指数的组分定性方法,并对101种多环芳烃化合物进行了定性,计算了保留指数;分析了6个平行样,得到22个多环芳烃组分浓度的相对标准偏差为2.64%～8.54%,回收率为74%～107%,方法检出限为2.05 μg/g.基于本方法分析的多环芳烃浓度信息,对4个不同原油进行了指纹比对,鉴别结果较好.     

原油空气氧化前后多环芳烃组分的气相色谱-质谱分析

采用柱层析法对空气氧化前后的原油进行族组分分离,利用气相色谱-质谱(GC-MS)分离测定其芳香烃组分,分析多环芳烃组分的变化.结果表明,随着氧化过程的进行,烷基化多环芳烃占多环芳烃的含量从氧化前的71.5%增加到92.0%(175℃)和90.2%(225℃).轻质组分萘和菲的优势逐渐被重质组分艹屈取代.侧链少的多环芳烃比侧链多的更易氧化.氧化后,其他稠环化合物蒽、萤蒽、芘、苯并蒽含量降低,苯并萤蒽含量增加;苯并芘在175℃氧化后含量降低,而在225℃氧化后含量增加.与此同时,175℃氧化后生成了原油所不含有的三芳甾烃、联苯和苯并呋喃.     

Biodegradation of Crude Oil by a Newly Isolated Strain Rhodococcus sp. JZX-01

A highly efficient oil-degrading bacteria JZX-01 was isolated from the oil-contaminated soil of the seacoast near the Boxi Offshore Oil Field of China. Morphological, physiological, and 16S rDNA gene sequence analyses indicated that JZX-01 was assigned to the genus Rhodococcus sp. This strain decomposed 65.27?±?5.63 % of the crude oil in 9 days. Gas chromatography–mass spectrometry analysis showed that even the long-chain hydrocarbons (C31–C38) and branched alkanes (pristine and phytane), which were regarded as the stubborn ones, could be degraded. Further study showed that the bacteria still has good oil degradation ability at low temperatures as well as under high salt conditions. Moreover, JZX-01 was found to have a biosurfactant-producing capacity, which significantly favors the surface tension reduction and crude oil degradation. The promising isolated strain Rhodococcus sp. JZX-01 could be further used for the bioremediation of oil-polluted soil or seawater in a wide range of temperatures and high salt conditions.     

Enhanced Crude Oil Sorption by Modified Plant Materials in Oilfield Wastewater Treatment

The treatment of oilfield wastewater with high crude oil content and complex composition is a problem requiring considerable attention. In order to effectively remove crude oil contained in wastewater, in this work, rice straw, as an oil-absorbing material, was modified and used as a sorbent for crude oil. Rice straw was modified with alkali and cetyltrimethylammonium chloride (CTAC) by simple substitution reaction. The adsorption capacity of modified rice straw for oil was evaluated. The results illustrate that the adsorption rate of rice straw for crude oil was increased from 0.83 to 8.49 g/g, with the optimal conditions of 18% NaOH reacted for 90 min at 50 °C and 2% CTAC reacted for 60 min at 20 °C. The proposed modification method could be used for different materials to enhance the adsorption rate. The results of the contact angle test show that the modified straw changed from hydrophilic to hydrophobic, which may be the main reason for the improvement in the oil absorption rate. Finally, the surface structure of rice straw was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and N₂ adsorption–desorption isotherms, which further confirmed the hydrophobicity of the modified rice straw.     

Characterization of Crude Oil Equivalent Alkane Carbon Number (EACN) for Surfactant Flooding Design

Equivalent alkane carbon number (EACN) of crude oil reflects the hydrophobicity of the crude oils, thus it would be helpful to estimate the EACN of crude oil before fine tuning the surfactant selection for enhanced oil recovery field application. In this study, we used the titration methodology to quantify the EACN values for several crude oil samples retrieved from the targeted mature oil fields. The results showed that the method of using extended surfactant was simpler but reliable to determine the EACN of crude oils. The resulting EACN for these crude oils was found to be in the range of 6.0–11.3.     

植物油酸／Tween－60复配体系与原油间的界面张力

研究了植物油酸及其中和物／Ｔｗｅｅｎ－６０复配体系与大庆原油间界面张力随各种因素的变化规律。结果表明，当０．４０％ＮａＣｌ存在时，植物油酸中和度为０．８５，ＮａＣｌ浓度为０．９０％时，复配以０．１０％Ｔｗｅｅｎ－６０既可使体系兼容，又可使之保持较低界面张力。     

无机盐强化烷基多苷清洗石油污染土壤的机理

研究了无机盐对一种烷基多苷(APG)产品APG1214物理化学性质的影响, 以期解释无机助剂对APG1214清洗老化石油污染土壤的强化作用. 实验发现无机助剂能够显著降低APG1214的临界胶束浓度(CMC)和浊点, 提高其表面活性, 对除油过程有促进作用. 利用动态光散射(DLS)和透射电镜(TEM)研究了无机助剂对APG1214聚集体流体力学半径(Rh)和形态的影响, 发现低浓度无机助剂可减小APG1214聚集体尺寸, 而高浓度助剂则增加聚集体尺寸. 研究结果显示出APG1214与常见非离子表面活性剂不同的特性. 洗油后溶液中表面活性剂聚集体的Rh分布明显变窄, 但平均半径有所增加; TEM观察显示, 洗油后溶液中囊泡壁明显变厚, 证明增溶是APG1214去除石油污染物的一条途径. 本实验得到的结论为APG1214在石油污染土壤修复方面的应用提供了依据, 并为在其他领域更好地利用这类绿色表面活性剂提供了参考.     

植物油酸／Tween—60复配体系与原油间的界面张力

研究了植物油酸及其中和物／Ｔｗｅｅｎ－６０复配体系与大庆原油间界面张力随各种因素的变化规律，结果表明，当０．４０％ＮａＣｌ存在时，植物油酸中和度为０．８５，ＮａＣｌ浓度为０．９０％时，复配以０．１０％Ｔｗｅｅｎ－６０既可使体系兼容，又可使之保持较低界面张力。     

Biodegradation of Crude Oil from the BP Oil Spill in the Marsh Sediments of Southeast Louisiana, USA

The significant challenges presented by the April 20, 2010 explosion, sinking, and subsequent oil spill of the Deepwater Horizon drilling platform in Canyon Block 252 about 52 miles southeast of Venice, LA, USA greatly impacted Louisiana??s coastal ecosystem including the sea food industry, recreational fishing, and tourism. The short-term and long-term impact of this oil spill are significant, and the Deepwater Horizon spill is potentially both an economic and an ecological disaster. Microbes present in the water column and sediments have the potential to degrade the oil. Oil degradation could be enhanced by biostimulation method. The conventional approach to bioremediation of petroleum hydrocarbon is based on aerobic processes. Anaerobic bioremediation has been tested only in a very few cases and is still considered experimental. The currently practiced conventional in situ biorestoration of petroleum-contaminated soils and ground water relies on the supply of oxygen to the subsurface to enhance natural aerobic processes to remediate the contaminants. However, anaerobic microbial processes can be significant in oxygen-depleted subsurface environments and sediments that are contaminated with petroleum-based compounds such as oil-impacted marshes in Louisiana. The goal of this work was to identify the right conditions for the indigenous anaerobic bacteria present in the contaminated sites to enhance degradation of petroleum hydrocarbons. We evaluated the ability of microorganisms under a variety of electron acceptor conditions to degrade petroleum hydrocarbons. Researched microbial systems include sulfate-, nitrate-reducing bacteria, and fermenting bacteria. The results indicated that anaerobic bacteria are viable candidates for bioremediation. Enhanced biodegradation was attained under mixed electron acceptor conditions, where various electron-accepting anaerobes coexisted and aided in degrading complex petroleum hydrocarbon components of marsh sediments in the coastal Louisiana. Significant degradation of oil also occurred under sulfate-reducing and nitrate-reducing conditions.     

Feasibility Study of Crude Oil Fields by Thermal Analysis Techniques

This paper investigates the minimum oil content necessary for self-sustained combustion, which is introduced as a criterion for the selection of suitable reservoirs for in-situ combustion processes. Differential scanning calorimetry was used to determine the heat values of oil-limestone mixtures. The minimum temperature required for the total consumption of the fuel was obtained by thermogravimetry (TG/DTG). The minimum amount of oil necessary to sustain combustion was calculated from these two parameters and compared with the oil content of the reservoir. Reservoirs with an oil content greater than or equal to this minimum value were considered feasible. It was seen that the fields examined are generally not suitable for in-situ combustion processes. This revised version was published online in August 2006 with corrections to the Cover Date.     

原油中含氧化合物的质谱分析

本文介绍自原油分离含氧化合物,酯化混合酸和用毛细管气相色谱-质谱(GC-MS)鉴定其组分的方法。色谱-质谱分离并鉴定出C_8—C_(30)的脂肪酸、分子量为484和498的二对藿烷酸的立体异构体,烷基酚,邻苯二甲酸酯等,并首次发现石油中含有癸二酸二异辛酯类组分。     

气相色谱与紫外分光光度法评价石油烃类污染物的微生物降解过程

采用联合使用毛细管气相色谱法和紫外可见分光光度法,系统地研究了一种混合微生物体系对柴油的降解过程。研究结果表明,这两种简单方法的简单组合,弥补了单一方法的局限性,能够监测石油烃类污染物总体和主要组分的降解程度,实现对烷烃和芳香烃降解的分别评价。同时还表明,本实验采用的混合微生物体系对柴油具有很强的降解能力。     

原油与沥青质热解产物的GC-MS分析

较严重生物降解的原油没有正构烷烃,甚至缺失类异二戊烯烃,给油源研究造成一定困难.这种降解油中沥青质含量很高,用沥青质热解可产生相当量的正构烷烃和其它的烃类成分,例如:类异戊二烯烃、甾烷、萜烷、芳烃等成分也会有所变化.本文研究它们的变化特点、变化的幅度,找出一定的规律性,以对利用原油沥青质热降解产物用于油源对比时分析它们的相似性有所帮助.实验证明,总体上看沥青质的热降解产物与原油的烃类分布上比较相似,但并不一致,有的差距比较大,应该做一些校正,有的则比较稳定可靠.     

Aerobic Biodegradation of a Sulfonated Phenylazonaphthol Dye by a Bacterial Community Immobilized in a Multistage Packed-Bed BAC Reactor

A microbial community able to aerobically degrade the azo dye Acid Orange 7 was selected from riparian or lacustrine sediments collected at sites receiving textile wastewaters. Three bacterial strains, pertaining to the genera Pseudomonas, Arthrobacter, and Rhizobium, constitute the selected community. The biodegradation of AO7 was carried out in batch-suspended cell culture and in a continuously operated multistage packed-bed BAC reactor. The rapid decolorization observed in batch culture, joined to a delay of about 24 h in COD removal and cell growth, suggests that enzymes involved in biodegradation of the aromatic amines generated after AO7 azo-bond cleavage (1-amino-2-naphthol [1-A2N] and 4-aminobenzenesulfonic acid [4-ABS]), are inducible in this microbial consortium. After this presumptive induction period, the accumulated byproducts, measured through COD, were partially metabolized and transformed in cell mass. At all azo dye loading rates used, complete removal of AO7 and 1-A2N was obtained in the multistage packed-bed BAC reactor (PBR).; however, the overall COD (η _COD ) and 4-ABS (η _ABS ) removal efficiencies obtained in steady state continuous culture were about 90%. Considering the toxicity of 1-A2N, its complete removal has particular relevance. In the first stages of the packed-bed BAC reactor (Fig. 4a–c), major removal was observed. In the last stage, only a slight removal of COD and 4-ABS was obtained. Comparing to several reported studies, the continuously operated multistage packed-bed BAC reactor showed similar or superior results. In addition, the operation of large-packed-bed BAC reactors could be improved by using several shallow BAC bed stages, because the pressure drop caused by bed compaction of a support material constituted by small and fragile particles can be reduced.     

阴阳离子表面活性剂混合体系对原油的乳化及增粘行为

利用阴阳离子表面活性剂复配技术,实现了高含水量原油体系的乳化及增粘.通过调整表面活性剂分子结构,解决了阴阳离子表面活性剂复配体系在油田模拟水中的溶解度问题.确定了相关体系高含水量油包水(W/O)乳状液的表面活性剂浓度,研究了可以产生高含水量油包水乳状液的油水混合体积比范围,并研究了温度、pH值、油水混合比例和离子强度对乳化及增粘作用的影响.获得了一系列具有优良乳化效果和乳状液稳定性的体系,其中部分体系粘度可增大80倍.这对于三次采油提高采收率有重要意义.     

阴阳离子表面活性剂混合体系对原油的乳化及增粘行为

利用阴阳离子表面活性剂复配技术,实现了高含水量原油体系的乳化及增粘. 通过调整表面活性剂分子结构,解决了阴阳离子表面活性剂复配体系在油田模拟水中的溶解度问题. 确定了相关体系高含水量油包水（W/O）乳状液的表面活性剂浓度,研究了可以产生高含水量油包水乳状液的油水混合体积比范围,并研究了温度、pH值、油水混合比例和离子强度对乳化及增粘作用的影响. 获得了一系列具有优良乳化效果和乳状液稳定性的体系,其中部分体系粘度可增大80倍. 这对于三次采油提高采收率有重要意义.     

费谢尔判别法鉴别原油/燃料油

以多环芳烃作为变量,建立了原油、燃料油属性鉴别的费谢尔判别法。分别测定了来自不同国家和地区的26个原油样品和25个燃料油样品中8种多环芳烃的含量,并将它们作为判别变量。借助SPSS 16.0进行费谢尔判别分析,建立费谢尔判别函数。将未知样品的判别变量值代入后,可以快速地得知样品的类别。结果表明,以多环芳烃作为判别变量进行原油、燃料油费谢尔判别快速而准确。     

Synergistic Effect of Sarocladium sp. and Cryptococcus sp. Co-Culture on Crude Oil Biodegradation and Biosurfactant Production

This study was conducted to evaluate the co-culture ability of two yeast (Sarocladium sp. and Cryptococcus sp.) isolates as compared to their individual cultures in surfactant production and oil degradation. The results showed that individual culture of each strain was capable of producing surfactant, degrading oil, and pyrene; also, a synergistic effect was observed when a co-culture was applied. Oil removal and biomass production were 28 and 35% higher in the co-culture than in individual cultures, respectively. To investigate the synergistic effects of mix culture on oil degradation, the surface tension, emulsification activity (EA), and cell surface hydrophobicity of individual and co-culture were studied. A comparison between the produced biosurfactant and chemical surfactants showed that individual culture of each yeast strain could reduce the surface tension like SDS and about 10% better than Tween 80. The results showed that the microbial consortium could reduce the surface tension more, by 10 and 20%, than SDS and Tween 80, respectively. Both individual cultures of Sarocladium sp. and Cryptococcus sp. showed good emulsification activity (0.329 and 0.412, respectively) when compared with a non-inoculated medium. Emulsification activity measurement for the two yeast mix cultures showed an excellent 33 and 67% increase as compared to the individual culture of Sarocladium sp. and Cryptococcus sp., respectively. The cell surface hydrophobicity of Sarocladium sp. and Cryptococcus sp. increased (38 and 85%) when the cells were treated with pyrene as a hydrophobic substrate for four generations. Finally, a 40% increase for pyrene degradation was measured in a co-culture of the two yeast mix culture. According to the results of the present study, the co-culture system exhibited better performance and this study will enhance the understanding of the synergistic effects of yeast co-culture on oil degradation.