【作者】 孟庆玲；

【导师】 张凤君；

【作者基本信息】 吉林大学 ， 环境工程， 2012， 博士

【摘要】 在石油勘探开发过程中，从钻井工程施工到采油、工艺处理、输油、储油等各个环节，都不同程度地存在着石油的泄漏，造成地下水的严重污染。石油中含有许多毒性较强的物质，其中许多组分具有致癌、致畸和致突变作用，对人体健康和生态系统的安全都构成巨大威胁。因此，对石油类污染地下水的修复和治理研究已经迫在眉睫。目前，用于石油类污染地下水的治理主要包括异位修复和原位修复两种方式。其中，空气曝气技术（Air-sparging,AS）术和生物曝气技术（Bio-sparging,BS），是近年来迅速发展起来的地下水污染原位修复技术，因其具备可持续原位处理多种污染物、处理效果好、对环境扰动小、安装施工方便及成本低等显著优点，已成为国际上地下水污染原位修复的主要发展方向。国外在空气曝气和生物曝气技术修复石油类污染地下水方面已有成功实例，但在我国少见相关文献报道，因此，积极开展有关空气曝气和生物曝气技术修复石油类污染地下水的尝试和探索研究是十分必要的。本论文以国家水体污染控制与治理科技重大专项“松花江沿岸地下水污染控制关键技术及工程示范课题”的子专题“松花江沿岸地区浅层地下水石油类污染的修复技术”为依托，以地下水中石油类污染物为修复目标，采用经济、高效、对环境扰动小的生物曝气和空气曝气技术作为修复手段。结合场地水文地质条件及地下水污染特征，开展室内模拟实验。模拟污染场地地下水为第四系松散岩类孔隙微承压水，含水层厚度约17m，由上至下，含水介质由黄褐色细纱、粉砂逐渐过渡到砂砾，岩性颗粒逐渐变粗。地下水位观测资料显示，污染场地地下水流方向为东南至西北方向，水位埋深约3.4m，平均水力坡度为5‰。污染场地地下水的主要补给来源为微波岗地地下水侧向径流补给，径流条件和赋存规律与地形地貌、岩性密切相关，排泄方式主要为侧向径流排泄。论文以0#柴油为石油基底，选取苯、二甲苯、萘作为目标石油污染物，砾砂、粗砂和中砂为模拟含水层介质。首先进行了静态吸附实验研究，考察了污染物在介质中的吸附时间和吸附特性。实验结果表明：污染物在各含水层介质的吸附平衡时间为24h，污染物在介质中的吸附符合线性吸附，污染物在介质中吸附容量大小顺序依次为柴油、萘、二甲苯、苯；3种含水层介质对污染物的吸附能力大小顺序为中砂、粗砂、砾砂，污染物在中砂上吸附量最大。表明砂土的粒径越小，对污染物的吸附越大，在AS处理污染物的过程中，去除难度就越大。AS运行过程中影响因素研究通过土柱模拟实验进行，实验结果表明：曝气量和介质渗透性对AS的修复效果有较大影响，污染物的去除效率随着曝气量的增加而增大，但曝气量超过300mL/min，污染物的去除率不随曝气量的增加而增加；介质渗透性越强，污染物的去除率越高；对于渗透系数较低的中砂介质，间歇曝气污染物的去除率好于连续曝气效果，对于渗透系数相对较高的砾砂和粗砂介质，两种曝气方式效果相差不大。AS运行过程中的影响半径和修复效果研究通过砂槽实验进行，采用电阻层析成像技术测定AS过程中的影响半径。实验结果表明：随着曝气量的增加，影响半径不断增大，但当曝气量增大到一定量后，影响半径不再增大；在有边界的槽子存在边壁效应，即当曝气量达到极限值后，气体随着槽子的边壁逸出，影响曝气效果；单井曝气时，曝气量为0.16m3/h的影响半径明显大于曝气量为0.12m3/h；在非均匀介质中曝气影响半径不是以曝气井为中心对称分布的，存在气体偏流和绕流现象，曝气影响区域基本呈倒锥形分布；双井曝气曝气量为0.28m3/h，在砾砂层、粗砂层及中砂层的影响半径分别为24cm、27cm和55cm。TPH和苯在含水层介质中的迁移速度较快，二甲苯在介质中具有中等程度的迁移，萘在土壤中具有比较低的迁移性；由于地下水流作用污染物在水平方向的迁移速度大于在垂直方向的迁移速度。曝气15天后，AS对TPH、苯和二甲苯的去除率分别为77.4%、75.6%和71.3%；在不同土壤介质层中AS去除效果也有差异，苯和二甲苯在中砂层中的去除效果要好于砾砂层和粗砂层，这主要是抽提井深入位置影响所致，抽提井穿过粉砂层深入中砂5cm，使得中砂层附近空气阻力较小，空气沿着阻力小的方向上升到中砂层，故在中砂层气体分布较多，AS的去除效果好；苯的总体去除率好于二甲苯。AS在去除污染物的过程中，还有相当一部难挥发的石油污染物残留而未被去除，一旦曝气停止，残留在介质孔隙中的污染物又重新向地下水中释放。对空气曝气前后出水水样进行GC/MS全扫描分析，空气曝气后污染物组分与曝气前基本相同。空气曝气技术去除了约为75%的污染物，还有相当一部难挥发的石油污染物残留而未被去除，同时在空气曝气技术存在曝气停止后，还会有部分吸附的污染物重新释放现象，因此对于地下水石油类污染仅采用空气曝气技术不能达到彻底去除污染物的目的，需要采用生物曝气技术对地下水石油类污染进行进一步的修复研究。通过筛选和驯化得到污染物降解菌群，分离得到5株降解单菌，其中2株为高效降解菌，菌B对苯、二甲苯、萘降解效果良好，菌C对TPH降解效果良好，菌B和菌C所属菌属分别为假单胞菌属和无色杆菌属。污染物最佳降解条件为，在8-15℃的低温环境下，最佳pH范围为6-8、DO浓度为4-7mg/L、投加氮磷营养盐。筛选得到高效降解菌满足本研究对菌种的要求，可以作为后续实验的菌种来源。微生物在地下水中的迁移规律、BS修复效果及去除机制研究在砂槽实验中进行。实验结果表明：微生物在介质中的迁移速度从大到小依次为砾砂、粗砂、中砂；介质吸附微生物量的顺序从大到小为中砂、粗砂、砾砂，微生物的迁移能力随着介质粒径的减小而降低，介质粒径是影响介质吸附微生物量的重要因子。生物曝气4个月后，TPH、苯和二甲苯最高去除率分别为88.2%、86.4%和81.7%，介质吸附微生物量对污染物的去除有重要影响，中砂的去除率好于粗砂和砾砂，苯的去除效果好于二甲苯，生物曝气对TPH、苯和二甲苯的去除较为彻底，污染物去除率均能达到75%以上。实验进行初期挥发作用是主要的去除机制，实验进行的中后期生物作用是主要的去除机制，由挥发去除污染物的百分比为46.24%，生物降解去除污染物的百分比为36.98%。生物曝气结束后，各混合烷烃都被显著降解。微生物降解后，碳原子数较少的直链烷烃优先被生物降解。对于目标污染物萘适合用生物曝气技术去除，不适合用空气曝气技术去除。苯、二甲苯、萘的降解动力学方程大部分与1级反应动力学方程拟合效果良好，苯的降解半衰期在0.4-1.7d之间，二甲苯降解半衰期在1.5-3.6d之间，萘的降解半衰期在4.4-7d之间。萃取不同时刻污染物代谢产物，通过全扫描图谱及检索出的代谢产物明确了微生物降解苯、二甲苯、萘的降解途径。更多还原

【Abstract】 In petroleum exploration and development process, drilling construction,petroleum extraction, fabrication processing, transportation and storage lead topetroleum leak inordinately and consequently cause serious pollution of groundwater.Petroleum contains many highly toxic substances that are carcinogenic, teratogenicand mutagenic, leading to a great threaten to human health and ecological systemsafety. Therefore, developing the cost-efficient remediation technology of petroleumcontamination groundwater is imminent.For petroleum contamination groundwater, the remediation technologies areex-situ and in-situ remediation technology. Recently, the air-sparging andbio-sparging are widely used in remediation of contaminated groundwater, due to itsmany advantages such as in situ treatment a variety of pollutants sustainable, goodtreatment efficiency, little disturbance to environment, easy installation andconstruction and low cost. There are many successful examples on petroleumcontaminated groundwater remediation by using air-sparging and bio-sparging abroad,but rare related reports exist in the literature in China. Therefore, it’s essential to carryout air-sparging and bio-sparging technology in remediation of contaminatedgroundwater.This paper supported by The National Water Pollution Control and ManagementTechnology Major Projects–Shallow Groundwater Pollution Control Subject of KeyRemediation Technology and Engineering Demonstration along the Bank ofSonghuajing River which was sub-project of The Remediation Technology of shallowgroundwater petroleum contamination along the Bank of Songhuajing River. By usingairsparging and biosparging which were economic, efficient, little disturbance ofenvironment technology as repair measures remediate petroleum contaminatedgroundwater.Based on the hydro-geological conditions of petroleum contaminated sites in Northeast of China, the lab scale experiments were setup. The groundwater ofcontamination site is Quaternary loose rock pore micro-pressure water. Thickness ofaquifer is about17m. Aquifer is brown fine sand, silty sand gradually transition togravel sand, rock particles gradually thicken from top to bottom. The groundwaterflow direction of contaminated sites is southeast to northwest, water depth is about3.4m, the average hydraulic gradient is5‰which showed the obtained observations data.The main supply source of the groundwater is lateral recharge from groundwater ofmicrowave form mound. The runoff conditions and occurrence regularity and areclosely related to topography and lithology. The main mode of excretion is lateral runoff discharge.In this study,0#diesel was selected as petroleum basement. Benzene, xylene andnaphthalene were selected as target petroleum pollutants. Gravel sand, coarse sand,medium sand and silty sand were used to simulated aquifers. The static adsorptionexperiments were investigated including pollutants of adsorption equilibrium time andadsorption characteristics in the media. The experimental results showed that thepollution adsorption equilibrium time were24h in aquifer and the adsorption ofpollutants fitted linear adsorption. The sequence of adsorption capacity of pollutantsin aquifer follows as: diesel, naphthalene, xylene and benzene. The sequence ofaquifer media adsorption capacity of pollutants follows as: medium sand, coarse sandand gravel sand. The largest adsorption capacity of pollutants was medium sand. It isdemonstrated that the smaller the particle size of sand is, the greater the adsorption ofpollutants is.A one-dimensional column was set up to study the effect of factors on theremoval rate of contaminants. The results showed that the air flow rate and mediumpermeability greatly affected AS remediation efficiency. The contaminant removalrate increased with the increment of air flow rate, but the removal rate increasedslightly when the flow rate exceeding300mL/min. The bigger the hydraulicconductivity is, the better the removal efficiency is with AS remediate contaminations.In the same operating time, pulsed air injection had advantages over continuous airinjection for medium sand with low hydraulic conductivity, while the effects of two air injection modes were similar for coarse sand and gravel sand with higher hydraulicconductivity.A two-dimensional laboratory sand tank was setup to study removal rate andradius of influence during AS operation. The results showed that increased air flowrate led to wider radius of influence. But when the air flow rate increased to a certainamount, the radius of influence was no longer increased. The tank which has side wallexist boundary effect during AS operation. The gas escapes with the side wall of thetank when the air flow rate reached maximum value influencing aeration effect. Thegas distribution is not presented axisymmetric around aeration well, existing bios flowand flow around in heterogeneous media. The shape of influence aeration area wasbasically inverter cone distribution. The radius of influence with air flow rate of0.16m3/h was greater than0.12m3/h with single aeration well. The radius of influencewere24cm,27cm,55cm in gravel sand coarse sand and medium sand with air flowrate of0.28m3/h.The migration rate of TPH and benzene were faster. Xylene hasmoderate migration rate while naphthalene was lowest. The migration rate ofpollutant was faster in horizontal than in vertical. In different media layers AS removeeffects are also different. The removal efficiency in medium sand is better than that incoarse sand and gravel sand. After15days’ running, the removal efficiencies of TPH,benzene and xylene reached up to77.4%，75.6%and71.3%. The removal efficiencyof benzene is better than of xylene. A number of non-volatile organic contaminantswhich remain exist in aquifer are difficult to remove. Once the aeration is stopped, theresidual contaminants in the medium will release to the groundwater.The75percents of contaminants was removed by air-sparging. A number ofnon-volatile organic contaminants which remain exist in aquifer are difficult toremove. Once the aeration is stopped, the residual contaminants in the medium willrelease to the groundwater. Therefore, petroleum contaminated groundwater was onlyused air-sparging which not achieve the purpose of completely remove pollutants, so this paper continue to remediate petroleum contaminated groundwater by usingbio-sparging. Through the screening and domestication get pollution degradationbacteria flora.5strains were obtained after separation and purification. Two strainswere high efficiency degradation bacterium. Bacteria B had good degradation effecton benzene, xylene and naphthalene while the bacteria C has good degradation effecton TPH. Bacteria B and C respectively belongs to Pseudomonas and Achromobacter.The optimal condition of pollutants degradation is that the temperature is8-15°C, pHis6-8, DO concentration is4-7mg/L, adding nitrogen and phosphorus nutrient source.Screened bacteria flora achieved the requirements in this study, the degrading bacteriacan be used as bacteria sources of follow-up experiments.A laboratory sand tank was setup to study migration rule of bacteria ingroundwater, removal rate of contaminants and removal mechanism by usingbio-sparging technique. The results showed that the sequence of transport velocity ofbacteria follows as gravel sand, coarse sand and medium sand. The sequence ofadsorption of bacteria in the aquifer follows as medium sand, gravel sand and coarsesand. After4months’ bio-sparging running, the removal efficiencies of TPH, benzeneand xylene were reached up to88.2%,86.4%and81.7%. The percentage of removalcontamination is46.24%by volatilization and36.98%by biodegradation.Naphthalene was fitted to remove by using bio-sparging not by air-sparging.Benzene, xylene and naphthalene degradation kinetic equation fit well tofirst-order kinetic equation. The degradation half-life of benzene was0.4-1.7d, ofxylene was1.5-3.6d, of naphthalene was4.4-7d. Extraction metabolites of pollutants atdifferent times and through the scan analyze the degradation pathway of benzene,xylene and naphthalene.Benzene, xylene, naphthalene degradation kinetic equation fit first-orderkinetic equation well. The degradation half-life of benzene was0.4-1.7d, of xylenewas1.5-3.6d, of naphthalene was4.4-7d. Extraction metabolites of pollutants atdifferent times and through the scan analyse the degradation pathway of benzene,xylene and naphthalene.更多还原