石油类污染场地的自然衰减作用

在野外石油类污染场地地质、水文地质调查的基础上,对场地地下水中总石油烃的吸附、生物降解等自然衰减作用进行研究。开展了砂质粉土、粉砂、细砂等场地包气带、含水层介质对总石油烃的吸附动力学实验、等温吸附实验、不同矿化度吸附实验、生物降解实验和挥发实验等。实验结果显示,砂质粉土、粉砂、细砂的吸附平衡时间分别为4、7和10 h;通过计算确定了每种介质对总石油烃的等温吸附模型。矿化度对介质吸附总石油烃能力的影响表现为,矿化度越高吸附量越高。生物降解实验结果表明,在场地水土条件下,降解能力最强,且降解符合一级衰减动力学方程。研究表明,地下水受到污染后,吸附、降解、挥发等自然衰减作用对地下水石油类污染物的去除具有非常重要的作用。     

石油类污染物在土壤中的吸附/解吸机理研究及展望

石油类污染物在土壤中的吸附与解吸研究是目前土壤学及环境科学研究的重要领域,石油类污染物在土壤中的吸附/解吸影响因素、机理及研究方法已有大量研究,但由于吸附/解吸传统研究方法受各种参数的限制,对影响因素、吸附模式、机理的研究难以进一步深入,多种影响因素之间的相互作用也是一个重要的研究方向;石油类污染物的吸附模式随着吸附方式的不同而适用于不同土壤的吸附,而用SPE技术可以从分子水平来认识吸附/解吸的本质。同时本文提出了石油类污染物在土壤中吸附/解吸机理研究中存在的问题,并展望未来的发展趋势。     

土壤对石油类污染物的自净作用——以中原油田三厂采油区为例

为探究土壤对石油类污染物的自净作用,选取典型受石油污染的中原油田三厂采油区的土壤为研究对象,通过两组自净试验和淋洗试验,详细分析对比了研究区内典型的粉土和粉质黏土的吸附降解能力,结果表明粉土比粉质黏土对石油类污染物有更好的自净能力。同时阐明了石油类污染物在土壤中的降解过程主要为吸附挥发、淋溶及微生物降解,其中微生物降解是石油类污染物的最终归宿。     

土壤/沉积物中石油烃微生物降解研究综述

结合目前国内外研究进展,综述了土壤和沉积物中石油烃污染物的来源、危害和生物降解的菌种及降解途径,分析了微生物性质和包括氧、营养物、温度、土壤/沉积物理化性质等环境因素对石油烃降解的影响,指出这些研究往往局限于某种特殊污染物、特殊污染降解菌种和单一条件下辅助降解方面,引入了人为因素的影响,造成与实际不符的降解假象。因此,自然条件下石油烃生物降解将成为重要的研究课题。     

油气田地区土壤-水环境中有机污染的数值模拟及模型预测

针对油气田地区的地下水污染日益突出问题，文章综合考虑石油类有机污染物在包气带中扩散、吸附解吸、分配和生物降解等环境行为，建立了土壤－水环境体系有机污染物迁移转化的非平衡动力学模型，并编制了RBCA有限元程序，预测污染物在土壤－水环境中浓度分布变化趋势，探讨了模拟参数κd、κ变化对有机污染物迁移的影响。模拟结果表明：吸附解吸速率参数的变化对污染物达到平衡状态起着决定性作用，其结果可为定量研究有机污染物在土壤－水环境中的归宿提供可靠的理论根据，同时为油气田勘探开发过程中的污染控制与治理措施提供依据和理论指导。     

吸附对土壤水环境中有机污染物生物降解过程的影响研究

在土壤水环境系统中,吸附作用是影响有机污染物生物降解过程的主要制约因素。污染物的吸附性越强,则其存在于土壤水溶液的重量百分比就越小,生物降解可能性也就越低。本文建立了定量描述吸附作用对有机污染物在土壤颗粒内部传输过程影响的数学模型。通过模型计算发现,有机污染物的土壤-水吸附分配系数Kd越大,则其从土壤颗粒内部传输到外部水溶液的速率就越小,总的降解速率也就越低。     

含沙水体污染物生物降解反应动力学研究

以含多组分的生活污水为模拟污染物,通过实验方法对含沙水体中污染物生物降解规律进行了研究,得出了污染物生物降解速率常数与含沙量的关系式。研究结果表明:(1)低浓度污染物在含沙水体中的生物降解过程符合一级反应动力学过程;(2)对同一粒径组泥沙而言,含沙量越大,污染物生物降解速度越快。即泥沙的存在促进了污染物的降解;(3)污染物生物降解速率常数随着含沙量的增大而增大,两者存在非线性的函数关系。含沙量增大到一定值时,降解速率常数趋于最大值。     

NKK开展土壤净化技术

日本NKK公司准备开展土壤改善业务。该公司已签订了有关使用美国BioGenesis Enterprises公司开发的工艺技术的协议。据NKK报道，该工艺使用高压水粉碎土壤，并应用生物降解表面活性化学试剂，来消除土壤中的有害物质。对基本生产流程的部分设备重新配置，该系统就能重新组合用于去除重金属、挥发性有机化合物、多氯联苯、石油污染物和Dioxins。该车载装置能去除小于70μm的土壤污染物，日均清除190m^3土壤。据BioGenesis报道，这项技术能去除85％－99％的土壤污染物，且剩余部分可采用生物降解作用再净化，去污成本从每吨40美元到每吨200美元。一旦净化作业完毕，就可将处理后的土壤送回其原处。     

包气带中原油的迁移和降解研究

在石油的开采和集输过程中,常常有大量的原油抛洒和泄漏,这对土壤和植物地造成严重污染,本文通过大量野外和室内的原油渗透试验,含油地层的淋滤试验和石油的生物降解试验,来研究石油污染物在包气带中迁移,转化和降解规律,从而地下水石油污染的潜在性作出科学的评价。     

甲苯在土壤地下水中迁移规律研究

石油泄漏导致甲苯等有机污染物污染土壤地下水,并且甲苯等石油类有机污染物对土壤地下水污染具有隐蔽性强、难以逆转等特点,污染治理难度大。因此,研究甲苯有机污染物在土壤地下水中运移规律是治理的关键。该文以某污染场地为研究区,以甲苯有机污染物为研究对象,考虑了淋滤、吸附的影响,采用模型计算方法,分析了甲苯在污染场地土壤地下水中迁移规律。结果表明：甲苯在土壤地下水中迁移过程中,淋滤作用对甲苯浓度变化影响显著;吸附影响下扩散作用及地下水位变化对甲苯迁移产生的影响均受到抑制。该文获得的甲苯在土壤地下水中迁移规律可为甲苯有机污染物污染场地修复提供依据。     

土壤石油污染的生物修复技术

采用生物修复技术对土壤石油有机污染进行治理以效率高、安全性好、无二次污染、易于管理而受重视。文章结合国内外的最新研究成果。对生物修复的处理过程、技术工艺等方面进行了论述。     

A field experiment and numerical modeling of a tracer at a gravel beach in Prince William Sound,Alaska

Oil from the 1989 Exxon Valdez oil spill persists in many gravel beaches in Prince William Sound (Alaska, USA), despite great remedial efforts. A tracer study using lithium at a gravel beach on Knight Island, Prince William Sound, during the summer of 2008 is reported. The tracer injection and transport along a transect were simulated using the two-dimensional numerical model MARUN. Model results successfully reproduced the tracer concentrations observed at wells along the transect. A sensitivity analysis revealed that the estimated parameters are well determined. The simulated spatial distribution of tracer indicated that nutrients applied along the transect for bioremediation purposes would be washed to the sea very quickly (within a semi-diurnal tidal cycle) by virtue of the combination of the two-layered beach structure, the tidal fluctuation and the freshwater flow from inland. Thus, pore-water samples in the transect were found to be clean due to factors other than bioremediation. This may explain why the oil did not persist within the transect.     

Application of indigenous microbial consortia in bioremediation of oil-contaminated soils

Bioremediation of oil spillage in soils using consortia of microbes beckons much exploration. The present study involves bioremediation of oil-contaminated soils from north Chennai, India, using indigenous microbial consortia. Totally, 32 positive oil degrading isolates were obtained from 3 different locations, i.e., petrol filling stations, automobile workshops and oil refineries. Substrate utilization patterns of individual isolates and the consortial sets were observed. Mixture of three common hydrocarbons (petrol, diesel and engine oil) was used for studies. The substrate oil utilized by consortia was taken for thin-layer and column chromatography which perfectly resulted in varied fractions of oil compared to the unused oil as control. The best consortia were used directly for bioremediation experiment. Three different oil-contaminated soils were used and bioremediation patterns were observed. The rate of bioremediation differed within soils, nevertheless all soils were almost 100 % reclaimed within 30 days. Bioremediation kinetics showed that the process corresponds to first-order kinetics and kinetic constants for the different soils ranged from 0.051 to 0.077/day. Assessment of detoxification of acute phytotoxicity owing to the pollutant oil was done, and results observed were significant. An increase of 25, 300 and 212 % in germination index, average growth index and sustenance index, respectively, of Trigonella foenum-graecum Linn. in treated soils was observed, compared to untreated soils. Thus, this study confirmed that microbes in ‘Consortial Union’ serve as better treating agents in bioremediation of oil-contaminated soils than individual microorganisms.     

Application of bioremediation in oil contaminated soil

The long-term oil exploitation in oil fields has led to pollution of surrounding soil, creating a serious ecological problem. In order to promote and improve the application of microbial remediation in oil contaminated soil, experiment is carried out in polluted area in Zhongyuan Oilfield. In the experiment, indigenous microorganisms and other physical and chemical methods are employed, ryegrass is grown, and environmental factors in soil are regulated to degrade the oil and treat the polluted soil. Results show that when the average oil content in the soil is about 523.08 mg/kg, 65 days’ remediation through plants and microorganisms could help bring the oil content down to 74.61 mg/kg, achieving a degradation rate of 85.74%; through salinity treatment, salt content in soil is reduced by 62.93-82.03% to 399-823 mg/kg from previous 2.22 g/kg. Through this experiment, the bioremediation method is improved and its effectiveness and feasibility are testified. The result has been applied in Zhongyuan Oilfield and has brought fair ecological and economic benefits, providing technical support to the treatment of contaminated soil of the same kind, and offering some insights to the treatment of soil contaminated by other organic pollutants.     

Control of emission rates

The advection-diffusion equation is used for describing the dispersion of pollutants in a limited area. Methods for preventing dangerous levels of pollutants in ecologically important zones are suggested. The methods are based on the control of emission rates of sources and use the direct and adjoint estimates of the average pollution concentration in the zones. While the direct estimates use solutions of the pollution transport problem and permit to study the ecological situation in the whole domain, the adjoint estimates allow getting information only in the selected zones of the domain. The adjoint estimates are obtained with solutions to the adjoint problem and depend explicitly on the positions of the sources and their emission rates, and on the initial distribution of pollutants in the region. In each such estimate, the adjoint problem solution serves as the influence function that shows the quantitative contribution of every source into the pollution of the corresponding zone. This makes the adjoint estimates very efficient tools in the study of the model response to changes in emission rates and initial conditions, as well as in the development of control strategies. Both non-optimal (sufficient) and optimal control strategies are suggested. Each strategy consists in reducing the emission rates of sources, and defines maximum allowable intensity (in case of optimal control), or sufficient intensity (in case of sufficient control) of each source to avoid violations of hygiene standards. Such criteria are designed taking into account dynamic conditions in the atmosphere or ocean (sea), that is, the processes of propagation, dispersion and transformation of pollutants, as well as the number of sources to control, their locations and the sanitary norms. The control methods developed are illustrated with simple examples using two-dimensional dispersion models. However, these methods can also be applied to three-dimensional models. As an example, in the last part of the article, a three-dimensional model of dispersion is considered. In addition, to expand the scope of application of the methods of control of the intensity of sources, the optimal control strategies are applied to a source that emits a chemical substance to clean aquatic systems contaminated with biofilms (remediation) or oil (bioremediation).     

致密油藏压裂双水平井参数优化研究

多段压裂水平井能有效地提高致密油藏单井产量,双水平井的使用则会增大增产效果,但其压后产量影响因素并不是很明确。基于渗流力学理论,分析压裂双水平井流体流动机理,建立了考虑启动压力影响的油藏—裂缝系统分段压裂双水平井数值模型,采用网格加密方法和控制变量法,计算分析了地质因素和工程因素对双水平井压后产量的影响,并使用正交试验方法把不同的裂缝参数和特征对水平井产量的影响进行了主次排序。结果表明:地质因素中的基质孔隙度和渗透率对压后单井产量影响最大;工程因素中的水平井筒长度和裂缝导流能力对水平井产量影响较大,并且相关因素的影响力排序为:水平井筒长度>裂缝导流能力>裂缝长度>水平井筒间距>裂缝条数。研究结果对致密油藏双水平井压裂理论及优化设计具有现实的实践指导意义。     

Comparison of biostimulation and bioaugmentation for remediation of soil contaminated with spent motor oil

Aerobic fixed bed bioreactors were used to study and compare biostimulation and bioaugmentation for remediation of soil contaminated with spent motor oil. Bioaugmentation using consortium of bacteria and biostimulation using inorganic fertilizer and potassium dihydrogen orthophosphate were investigated. The bioremediation indicators used were the oil and grease content removals, total heterotrophic bacteria counts and carbon dioxide respiration rates. Results showed that biodegradations were very effective with 50, 66 and 75 % oil and grease content removal efficiencies for control, bioaugmentation and biostimulation respectively after ten weeks. Carbon dioxide respiration followed similar pattern as the oil and grease content removals. Biostimulation option has the highest carbon dioxide generation (6 249 mg/kg) and the control with the least (4 276 mg/kg). Therefore, the biostimulation option can be used to develop a realistic treatment technology for soils contaminated with spent motor oil.     

Hydrocarbon-Degrading Bacteria and Paraffin from Polluted Seashores 9 Years after the Nakhodka Oil Spill in the Sea of Japan

Pollution of petroleum hydrocarbons, in particular oil spills, has attracted much attention in the past and recent decades. Oil spills influence natural microbial community, and physical and chemical properties of the affected sites. The biodegradation of hydrocarbons by microorganisms is one of the primary ways by which oil spill is eliminated from contaminated sites. One such spill was that of the Russian tanker the Nakhodka that spilled heavy oil into the Sea of Japan on January 2, 1997. The impact of the Nakhodka oil spill resulted in a viscous sticky fluid fouling the shores and affected natural ecosystems. This paper describes the weathering of hydrocarbon-degrading bacteria （genus Pseudomonas） and crystallized organic compounds from the Nakhodka oil spill-polluted seashores after nine years. The Nakhodka oil has hardened and formed crust of crystalline paraffin wax as shown by XRD analysis （0.422, 0.377, and 0.250 nm d-spacing） in association with graphite and calcite after 9 years of bioremediation. Anaerobic reverse side of the oil crust contained numerous coccus typed bacteria associated with halite. The finding of hydrocarbon-degrading bacteria and paraffin wax in the oil crust may have a significant effect on the weathering processes of the Nakhodka oil spill during the 9- year bioremediation.     

电化学导流法提高原油采收率试验研究

电化学导流提高原油采收率技术,在油田各个开发阶段都可达到增油降水的效果.目前多数主力油层内部剩余油分布零散,注水效果差,新增储量的油层大多数是渗透率低、物性差的薄油层.现场试验证明,应用电动法这一新技术,已初步实现了增加原油渗流速度、提高油水流动的相对渗透率和解除油层堵塞等的效果,工艺上是可行的.且用导线传输直流电场与其它传输方式相比,对井口及地面通电设备的安全性也较好.     

黄土地区石油污染土壤生物修复的强化技术初探

以石油为典型污染物,在本次试验前期工作筛选保藏的众多优势石油降解细菌中选择4株降解能力突出的菌,对该4菌株(分别编号为A、B、C、D)进行随机混合构建优势降解菌群。结果表明：菌群A-C-D降解石油能力最强,3 d内原油的降解率达到了39.67%,比单菌除油率提高了13.21%;对该菌群的最佳投加配比进行确定,菌群的最佳接种配比为A∶C∶D=1∶2∶0.5,3 d内菌群A-C-D在不同接种配比情况下降解率变化范围为27.8%~44.2%,最高值与最低值相差16.4%,因此菌群间各菌必须维持在一定的数量配比的情况下才能达到理想的降解效果。对影响生物修复效果的环境因素,如营养物质(C、N、P)、表面活性剂、通氧量、电子受体等进行综合考虑,通过正交试验确定菌群A-C-D的最佳修复条件为：营养物质配比C∶N∶P为75∶8∶3,表面活性剂为0.5%,通气条件为六层纱布,电子受体H₂O₂的加入量为1.5%。在最佳修复条件下,3 d内原油的降解率达到6146%,比自然条件修复下的除油率4.7%提高了56.76%,较只进行菌种强化时的最高除油率44.2%提高了约17%。