Degradation Kinetics of Petroleum Contaminants in Soft-Water Systems

On the basis of site investigation and sample collection of petroleum contaminants in the soil-water-crop system in the Shenyang-Fushun sewage irrigation area, the physical-chemical-biological compositions of the unsaturated zone is analyzed systematically in this paper. At the same time, the degradation kinetics of residual and aqueous oils is determined through biodegradation tests. The studies show that dominant microorganisms have been formed in the soils after long-term sewage irrigation. The microorganisms mainly include bacteria, and a few of fungus and actinomycetes.After a 110-days‘ biodegradation test, the degradation rate of residual oil is 9.74%--10.63%, while the degradation rate of aqueous oil reaches 62.43 %. This indicates that the degradation rate of low-carbon aqueous oil is higher than that of highcarbon residual oil. In addition, although microbial degradation of petroleum contaminants in soils is suitable to the firstorder kinetics equation, the half-lives of aqueous oil, No. 20 heavy diesel and residual oil in the surface soils (L2-1, S1-1 and X1-1) are 1732 h, 3465 h and 17325 h, respectively.     

土壤对可溶性油的吸附作用及其影响因素分析

在沈(阳) 抚(顺) 灌区土-水-作物系统石油污染调查的基础上, 根据土壤非饱和带的结构和组成, 选择代表性的土壤剖面分别采集表土和底土, 分析土样的主要物理和化学性质, 系统测定不同土样对可溶性油吸附的动力学曲线和吸附等温线, 并分析了有机质、粘粒含量和含盐量对吸附作用的影响.结果表明, 土壤对可溶性油的吸附平衡时间为20~24h, 而且不同土样的吸附等温线均为直线型理想吸附.另外, 通过试验发现, 当水相中可溶性油低于一定浓度时, 不但不产生吸附, 反而使土壤中的残留油分释放出来.      

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。     

当地下水邂逅DNA:石油类有机污染及其生物降解

地下水科学与工程研究发展到今日,已经成为一门涉及多个领域的综合性学科。地下水污染的控制和修复研究更需要跨学科的技术和知识支持,而生物修复作为一种高效低耗修复的技术成为环境领域的研究热点。微生物因其自身特性及其对污染的降解主导特征对确定有机物污染场地的永续修复具有重要意义。简要地综述了地下水有机污染及其原位修复、有机污染物和地下环境微生物的交互作用,进一步聚焦生物降解机制、生物修复和细菌研究。在此基础上以某石油污染场地地下水为例,进行了地下水中分离微生物菌株及其降解特征的实验研究。结果表明:放线菌降解效果最好,细菌和真菌次之;两两组合降解效果好于单菌,表明存在协同作用;不同菌株混合降解率较低,表明具有拮抗作用。通过动力学实验得出对TPH的降解符合一级反应动力学方程及其降解速度和降解半衰期。就微生物对有机组分降解而言,烷烃和总石油烃降解规律相似;难降解组分降解率低,后期因烷烃转化使其浓度升高;苯浓度变化不大。微生物活性实验表明:活菌总数和脱氢酶活性与降解率呈正相关变化。运用生理生化及分子生物学方法鉴定得出了具体的菌种。     

石灰岩含水介质中苯系物（BTEX） 生物可降解性判识

    岩溶含水系统遭受石油烃污染的环境问题十分普遍。相对于多孔含水介质,石油烃BTEX在石灰岩含水介质中的生 物可降解性还不确定。为此,本研究开展了BTEX在石灰石和岩溶地下水介质中的静态微元体实验。经过77天的实验检测 分析,结果表明：（1） BTEX化合物在可利用电子受体溶解氧或硝酸盐存在条件下具有生物可降解性;（2） 向系统中补充 电子受体硝酸盐,具有促进生物降解的作用,其对BTEX的去除率可高达94%;（3） 未发现补充硫酸盐能够促进BTEX生物 可降解性;（4） 甲苯和二甲苯容易被生物降解,但苯的去除具有一定的难度。     

沈抚灌区石油污染土壤恢复方案的数值模拟

在沈抚灌区野外调查和室内外试验的基础上, 建立水分-反应性石油污染物运移的耦合数学模型, 采用数值方法模拟可溶性油(有效油) 的分布规律, 并定量分析了石油污染土壤不同恢复方案的可行性.研究结果表明, 土壤中的化学作用使可溶性油运移速度远远小于土壤水的入渗速度, 所以可溶性油主要分布在土壤耕作层之内, 难以通过灌溉污水的入渗直接污染地下水; 另外, 清污混合灌溉和改变作物结构的控制方案虽然可以大大降低土壤中可溶性油的含量, 但石油污染土壤的彻底恢复还必须依靠地表水或地下水的合理灌溉      

Numerical analysis of the transport and restoration schemes of aqueous oil in soils

 On the basis of field investigations and tests, the authors developed a coupling model of water and solute movement to quantitatively analyse the effects of climate condition, irrigation mode, chemical reactions and restoration schemes on aqueous oil (effective oil) distribution using the finite difference method. It is concluded from this study that the effect of strong adsorptive forces between aqueous oil and the soil matrix is the distribution of aqueous oil in the plough layer rather than its migration to groundwater. In addition, restoration schemes involving clean-wastewater mixing irrigation and crop-type adjustment may greatly reduce the aqueous oil concentrations, but clean surface water or groundwater irrigation must be used for complete restoration of the contaminated soils. Received: 26 April 2000 · Accepted: 21 August 2000     

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。     

石油污染土壤生物修复的强化技术

为探索石油污染土壤的高效修复方法,从实验室保存的优势菌中筛选得到4株降油效果最佳菌,采用摇床和恒温培养箱培养,对含油量为5％的石油污染土壤进行微生物菌剂强化处理和环境强化实验。微生物菌剂强化结果表明：4种菌和除油效果最好的A、C、D混合菌3d可将石油烃依次降解24％、19．81％、22．55％、26．46％、39．67％;并对该菌群的最佳投加配比进行确定,A、C、D菌群数量的最佳配比为Nn：Nc：No=1：2：0．5,3d内菌群A、C、D在最佳接种配比情况下可将石油烃降解44．2％。环境强化实验结果表明：A、C、D菌群在最佳修复条件营养物质C：N：P为75：8：3、表面活性剂为0．5％、通气条件为6层纱布、电子受体H2O2的加入量为1．5％下,3d内石油烃降解61．46％,比自然条件下修复的除油率4．7％提高了56．76％,较只进行菌种强化时最高除油率44．2％提高了约17％。     

Sorption kinetics of naphthalene and phenanthrene in loess soils

A laboratory study was executed to investigate the effect of surfactants to enhance sorption of polycyclic aromatic hydrocarbon (PAH) contaminants in loess soil. Phenanthrene and naphthalene were chosen as organic contaminant indicators in loess soil modified by the cation surfactant hexadecyltrimethylammonium (HDTMA) bromide. The kinetic behavior of sorption during transport in natural and modified loess soil was studied. The results indicated that sorption rate in the cation surfactant modified loess soils was at least 3 times faster than that of the natural soil. A first-order kinetics model fitted the sorption data well for both soils. The sorption rates of the two organic compounds were related to their primary residual quantity on the soils. The experiments showed that sorption amounts approached constant values approximately within 30 and 90 min for naphthalene and phenanthrene at 298–318 K, respectively. The rate constants, however, displayed negative correlation with increasing temperature. With changing temperature, the activation energy was calculated at –6.196–1.172 kJ/mol for naphthalene and –28.86–15.70 kJ/mol for phenanthrene at 298–318 K. The results can be used to predict the sorption kinetics of phenanthrene and naphthalene in loess soils, and in a wider perspective, be used to better understand the transport of petroleum contaminants in the soil environment.     

油藏底水与隔夹层对原油生物降解程度的控制效应

系统剖析流花11-1礁灰岩油藏储层烃类的生物降解特征, 揭示油藏底水与隔夹层对原油生物降解程度具有显著控制效应, 这使得油藏原油生物降解程度及其分布预测更加复杂化.研究发现, 流花11-1油藏具有统一的油水界面, 油源类型单一, 原油成熟度较高且分布较窄, 可能为短期快速充注所形成的油藏.原油普遍遭受生物降解, 降解程度均小于6级.垂向上, 隔夹层虽可引起局部储层烃类降解程度的倒转, 但单井油柱生物降解等级仍以储层与油水界面的距离为主要控制因素, 表现为降解程度由顶部向底部呈明显梯度变化, 油藏底水控制效应明显.横向上, 油藏降解程度的差异主要由隔夹层控制下储层内原油与活跃底水的接触程度不同导致.在隔夹层密集发育区流体运动受阻, 进而使微生物营养物质供应不足, 代谢物质交换不畅, 原油降解程度相对较低.在上述研究的基础上, 建立了油藏底水与储层非均质性对原油生物降解程度的控制效应模型, 并探讨了该方法在稠油油藏开发中的应用.      

Hydrocarbon biodegradation and soil microbial community response to repeated oil exposure

Bioremediation strategies continue to be developed to mitigate the environmental impact of petroleum hydrocarbon contamination. This study investigated the ability of soil microbiota, adapted by prior exposure, to biodegrade petroleum. Soils from Barrow Is. (W. Australia), a class A nature reserve and home to Australia’s largest onshore oil field, were exposed to Barrow production oil (50 ml/kg soil) and incubated (25 °C) for successive phases of 61 and 100 days. Controls in which oil was not added at Phase I or II were concurrently studied and all treatments were amended with the same levels of additional nutrient and water to promote microbial activity. Prior exposure resulted in accelerated biodegradation of most, but not all, hydrocarbon constituents in the production oil. Molecular biodegradation parameters measured using gas chromatography–mass spectrometry (GC–MS) showed that several aromatic constituents were degraded more slowly with increased oil history. The unique structural response of the soil microbial community was reflected by the response of different phospholipid fatty acid (PLFA) sub-classes (e.g. branched saturated fatty acids of odd or even carbon number) measured using a ratio termed Barrow PLFA ratio (B-PLFAr). The corresponding values of a previously proposed hydrocarbon degrading alteration index showed a negative correlation with hydrocarbon exposure, highlighting the site specificity of PLFA-based ratios and microbial community dynamics. B-PLFAr values increased with each Phase I and II addition of production oil. The different hydrocarbon biodegradation rates and responses of PLFA subclasses to the Barrow production oil probably relate to the relative bioavailability of production oil hydrocarbons. These different effects suggest preferred structural and functional microbial responses to anticipated contaminants may potentially be engineered by controlled pre-exposure to the same or closely related substrates. The bioremediation of soils freshly contaminated with petroleum could benefit from the addition of exhaustively bioremediated soils rich in biota primed for the impacting hydrocarbons.     

冻融循环对多年冻土区石油迁移影响试验研究

多年冻土区石油污染物迁移过程和特点、污染定量评价、防治和治理措施研发,都是目前寒区经济发展和能源开发迫切需要解决的重要课题.通过室内试验对土体温度场分布、水分分布和石油总量分布的监测分析,研究了冻融循环作用对迁移过程的影响机制.试验结果表明,冻融循环作用通过影响石油污染物本身的物理性质、土颗粒对石油污染物的吸附作用和土体内水相的分布和相状态,影响了石油污染物的迁移过程.原油黏度随温度的降低逐渐增加,使得原油在土体中的迁移能力降低.冻融循环是油水迁移的主要驱动力之一,随着冻融循环的增加,石油污染物和水分向上迁移并聚集,石油随土样高度增加逐渐减小,而水分随高度增加而增加且在一定的位置聚集.研究成果可为多年冻土区石油污染迁移过程和定量评价及防治治理提供重要基础和参考.     

油气藏中沥青垫的研究进展

沥青垫是油气藏中沥青质相当富集的含油储层带，其沥青质的相对含量为２０％￣６０％，而对应的油层中其值不足２０％，沥青垫在凝析油气藏和轻质油藏中出现的频率高，常位于非渗透性隔层之上的高孔隙和较高水平渗透率的砂岩储层中，研究表明沥青垫的主要形成机理为：脱沥青作用，重力分离作用，生物降解作用和油－水相互作用，石油运移作用。     

污水灌溉下土壤孔隙特征的CT定量分析

污水中的悬浮物、盐分和有机营养物对土壤孔隙状况产生了深刻的影响.通过室内模拟和CT(computed tomography)扫描的方法, 定量研究污水灌溉条件下土壤孔隙数、孔隙度及形态特征.结果表明: 与对照点相比, 污水灌溉区上层土壤总孔隙数和大孔隙数(当量直径≥1.00 mm)均显著升高, 而下层土壤总孔隙数、大孔隙数、粗孔隙数(当量直径为0.26~1.00 mm)、总孔隙度、大孔隙度和粗孔隙度均显著降低(p＜0.05);在模拟悬浮液和盐液灌溉条件下, 土壤总孔隙数、粗孔隙数和粗孔隙度均有所升高, 而大孔隙数、总孔隙度、大孔隙度和孔隙成圆率均有所降低; 在模拟营养液灌溉条件下, 土壤总孔隙数、大孔隙数、粗孔隙数和粗孔隙度均有所增加, 而孔隙成圆率有所降低; 对于研究区土壤来说, 悬浮液灌溉对土壤孔隙的影响效应强于盐液灌溉; 对于同种性质的污水灌溉来说, 污灌对对照点土壤孔隙的影响效应强于污灌区土壤.      

Kinetics of biodegradation of diesel fuel by enriched microbial consortia from polluted soils

Three microbial consortia were isolated from three polluted soils located at an oil refinery and acclimated to grow on diesel fuel as the sole carbon source. Batch experiments were then conducted with the three consortia to study the kinetics of diesel biodegradation. The effects of temperature (25, 30 and 35?°C) and diesel concentration (0.5, 1 and 3?%) on the biodegradation of diesel were analysed. Several species were identified in the acclimated microbial consortia, and some of them appeared in more than one consortium. Thermal inhibition was observed at 35?°C. In the rest of experiments, over 80?% of the substrate was degraded after 40?h of treatment. These results proved the good feasibility of using the polluted sites as sources of mixed consortia for hydrocarbon degradation. However, diesel degradation efficiencies and rates were very similar, suggesting that the acclimation process produced mixed consortia with very similar characteristics; in this context, origin of the soil sample was not a decisive factor. A simple Monod-type kinetic model was used to simulate the biodegradation process, and accurate results were obtained. The ?? _max values were between 0.17 and 0.34?h^?1. The results of this study revealed that the consortia can function at high concentrations of hydrocarbons without any sign of growth inhibition, which is important for the design of bioreactors for wastewater treatment with high concentrations of fuel.     

菲降解菌的降解特性及酶促反应动力学研究

通过对取自MBR膜生物反应器中的活性污泥加入菲进行富集培养、驯化,分离、纯化出一株能以菲为唯一碳源和能源的短杆状革兰氏阴性菌J-1,细菌长2～5μm,宽1～3μm;研究了初始底物浓度、温度、pH对菌株J-1降解菲的影响,探讨了菌株J-1胞内酶对菲降解的底物抑制动力学。试验表明:菌株J-1在48h内能将不同浓度菲的水溶液中的菲完全降解;菲浓度增加,达到完全降解的时间延长。温度对细菌的降解能力影响较大,菌株J-1对菲降解的最佳温度为28℃。1.15mg·L-1的菲,28℃时48h内能完全降解,而相同时间内10℃时的降解率仅为36.65%。菌株J-1对pH的波动具有一定的适应性,pH在一定范围内(6.0～8.4)变化对菲降解的影响不大,降解反应的最佳pH为7.2。菌株J-1对菲的降解符合一级动力学反应方程。较高的底物浓度对酶促降解反应具有抑制作用,酶促反应的最大速率常数vm=1.17mg·L-1·h-1,米氏常数Km=61.70mg·L-1;底物抑制常数kS=49.60mg·L-1;最佳底物浓度[S]opt=55.32mg·L-1。     

Impact of treated sewage sludge application on phosphorus release kinetics in some calcareous soils

Treated sewage sludge contains significant amount of phosphorus and is widely used in agriculture. Kinetics of P release in soils is a subject of importance in soil and environmental sciences. There are few studies about P release kinetics in treated sewage sludge amended soils. For this purpose, sludge was mixed with ten soils at a rate equivalent to 100 Mg sludge ha⁻¹, and P desorption was determined by successive extraction using 0.01 M CaCl₂ over a period of 65 days at 25 ± 1°C. Phosphorus release rate was rapid at first (until about first 360 h) and then became slower until equilibrium was approached. Average of P released within 360 h for the unamended and amended soils was about 65 and 73% of the total desorbed P, respectively. Zero-order, first-order, second-order, power function, simplified Elovich and parabolic diffusion law kinetics models were used to describe P release. First-order, Elovich, power function and parabolic diffusion models could well describe P release in the unamended and amended soils. Correlation coefficients between P release rate parameters and selected soil properties showed that in the control soils, calcium carbonate equivalent and Olsen-extractable P; and in the amended soils, calcium carbonate equivalent, cation exchange capacity, organic matter and Olsen-extractable P were significantly correlated with P release parameters. The results of this study showed that application of sewage sludge can change P release characteristics of soils and increase P in runoff.     

Impact of sewage sludge application on zinc desorption kinetics in some calcareous soils

Sewage sludge usually contains significant amount of Zinc (Zn) and is widely used in agricultural lands. A laboratory experiment was performed to determine Zn desorption characteristics in unamended and amended soils with sewage sludge. Ten calcareous soils were amended with 1 % (w/w) sewage sludge. Amended and unamended soils were incubated at field capacity at 25 ± 1 °C for 1 month. After incubation, the kinetics of Zn desorption in amended and unamended soils were determined by successive extraction with DTPA-TEA (diethylenetriaminepentaacetic acid-triethanolamine) in a period of 1–504 h at 25 ± 1 °C. The results of kinetics study showed that extracted Zn and desorption rate constants in the amended soils were significantly (p < 0.01) higher than in the unamended soils. The results showed that Zn desorption increased from 201 to 343 % in amended soil with respect to unamended soils. The amounts of desorbed Zn in the unamended soils ranged from 3.73 to 8.79 mg kg^?1, while the amounts of desorbed Zn in amended soils ranged from 11.47 to 17.66 mg kg^?1. Desorption kinetics of Zn in two soils conformed fairly well to first-order, parabolic diffusion and power function equations. The results of stepwise regression analysis indicated that calcium carbonate equivalent and clay could be used to estimate Zn desorption characteristics in DTPA-TEA solution in the amended and unamended calcareous soils. It can be concluded that sewage sludge applied to calcareous soils may enhance the source of Zn for the plants.     

Improved assessment of biodegradation extent and prediction of petroleum quality

Biodegradation of crude oil causes volumetrically important compositional changes, which lead to significant deterioration in quality, in particular during the early stages of alteration. To better understand these effects we focussed on a detailed assessment of light to moderate levels of alteration. We investigated a suite of 40 crude oil samples from five different petroleum systems to evaluate the extent of alteration occurring in reservoirs. Based on a comprehensive geochemical characterization, five individual crude oil sequences were defined, where compositional variability is mainly due to microbial activity in the reservoir. In particular, samples from the Gullfaks field (offshore Norway) and from a petroleum system offshore Angola illustrate that conventional molecular biodegradation parameters, such as the Pr/n-C₁₇ and Ph/n-C₁₈ alkane ratios are not suitable for defining the extent of biodegradation in petroleum reservoirs. Here, we suggest a new molecular biodegradation parameter, the degradative loss, that can be used to quantify depletion in individual crude oil constituents. The approach allows improved assessment of the extent of biodegradation in crude oil samples by means of the mean degradative loss. It is demonstrated that crude oil quality, as assessed from API gravity, can be predicted directly from the molecular composition of crude oils. Our data clearly indicate that the degradation patterns of light hydrocarbons and n-alkanes differ in different petroleum systems. This suggests that microbial communities are different and therefore generate different molecular degradation patterns which have to be evaluated individually for each system.