【作者】 马长文；

【导师】 仵彦卿；

【作者基本信息】 上海交通大学 ， 环境科学， 2007， 博士

【摘要】 受氯代烃类有机物污染的地下水环境修复,是环境领域的前沿科学问题之一。了解四氯乙烯（PCE）在含水层中的迁移和转化如对流、弥散、吸附、生物化学降解等环境行为,是研究地下水污染控制的前提,对掌握有机物污染机理及确定控制修复技术具有重要意义。本文采用室内批量试验、砂柱模拟试验及数值模拟方法,在实验室试验研究PCE在地下水环境中的各种行为特点。等温非平衡吸附研究显示:PCE在砂质含水层介质（孔径9 nm左右）中的吸附特性与有机碳含量(f_oc)有关。（1）f_oc为0.080～0.090%的固相介质对PCE的等温吸附能在2小时内达到吸附体系的表观平衡状态;影响吸附过程快慢及表观平衡时的单位介质吸附量的主要因素是孔内充填及毛细凝结作用。（2）f_oc在0.220～0.540%的砂质介质,影响其吸附过程及单位介质吸附量的主要因素是固相有机质的吸收作用。等温平衡吸附研究显示:（1）PCE在f_oc为0.080～0.090%的固相介质上的等温平衡吸附特性用由线性吸附模型和Langmuir吸附模型组合并经修正后的双模式模型描述的效果最好。（2）f_oc为0.220～0.540%的砂质介质对PCE的等温平衡吸附特性用线性模型描述的效果最好。（3）本文定义的与修正的双模式等温吸附模型相对应的阻滞因子（R）表达式,可用于量化描述PCE在此类含水层介质中因吸附作用而滞迟的迁移过程,在特定的溶质迁移环境下,R的大小与溶质液相浓度直接相关。采用零价金属铁、锌或厌氧微生物单独作用、零价铁和厌氧微生物联合作用（FeMB）、零价锌和厌氧微生物联合作用等技术降解去除污染物PCE,研究表明:（1）在25天的运行时间内,FeMB技术对PCE的去除率最高,达到99.9%;约有44%的PCE被降解为乙烯、乙炔、乙烷等无氯碳氢化合物。与其它几种技术相比,FeMB技术不仅对PCE的去除率最高,而且对PCE的降解脱氯程度也最高。（2）PCE及其降解中间产物的衰减过程符合准一级反应动力学模型。（3）在FeMB降解体系中,PCE的主要降解路径为PCE先后经历氢取代反应脱去一个氯原子转化成三氯乙烯（TCE）和二氯乙烯（1,1-DCE）,1,1-DCE再经历α-还原脱氯反应转化为乙烯,再经氢气加成反应转化为乙烷。这个路径不同于铁或微生物单独作用的反应体系,表明铁和微生物联合作用不仅能影响零价金属铁与PCE及其降解产物的反应速率,还能改变脱氯过程的反应路径。（4）根据降解反应动力学模型预测的结果显示,FeMB技术将反应体系中的PCE全部转化为无氯碳氢化合物所需的时间为150天,是所有降解反应体系中耗时最短的。研究结果表明FeMB技术是一项有巨大潜在意义的环境修复技术。基于室内试验结果建立的PCE在地下水中的物理性迁移模型、物理化学性迁移转化模型能很好的描述溶质PCE在模拟砂柱中的迁移转化规律,该模型是在经典对流弥散方程的基础上耦合了修正的双模式等温吸附模型和准一级反应动力学的溶质衰减模型而成,可用作PCE在地下水中的行为规律和最终归宿的预测分析。更多还原

【Abstract】 Advection, dispersion, adsorption and degradation are important factors affecting the transport and fate of chlorinated organics in groundwater. Batch tests, column tests and mathematical methods were applied to investigate the environmental behaviors of perchloroethylene （PCE） in groundwater. The researches aimed at the adsorption characteristics of PCE to sandy materials, the best remediation technique for the groundwater contaminated by PCE, the transport and transformation of PCE in groundwater and the mathematical model to describe the transport, fate and remediation of PCE in groundwater.The batch non-equilibrium adsorption tests of PCE to sandy materials with organic carbon percent (f_oc) ranging from 0.080% to 0.540% show that the apparent equilibrium can be reached in 2 hours. Pore filling and capillary condensation probably play an important role in sorption kinetics for the media with f_oc 0.080～0.090% while the uptake by organic matter plays an important role in sorption kinetics for the media with relatively high f_oc 0.220～0.540%.The adsorption isotherm of PCE to media with f_oc 0.080～0.090% fit the amended dual-mode model developed from Linear and Langmuir isotherm model while the adsorption isotherm of PCE to media with f_oc 0.220～0.540% fit Linear model. The corresponding retardation factor （R） was defined to describe the retardation transport of PCE in aquifer similar to media with f_oc 0.080～0.090%. In given adsorption system, the retardation factor decreases gradually while the solute concentration increases.The degradation tests of PCE was carried out in five groups of degradation systems, that is, zero-valent iron alone, zero-valent zinc alone, anaerobic microbial community alone, the combination of zero-valent iron and anaerobic microbial community （FeMB）, the combination of zero-valent zinc and anaerobic microbial community. The results show that within 25 days, the FeMB degradation system had the highest removal efficiency of PCE （99.9%）, and about 44% of PCE was degraded to the non-chlorinated hydrocarbons, for example, ethylene, acetylene and ethane, it suggests that the FeMB remediation technique can dechlorinate more PCE and the reaction intermediates to less-chlorinated organics or non-chlorinated hydrocarbons. The results also showed that the degradation of PCE and its intermediates fit the pseudo-first-order kinetic reaction model. The major pathways of PCE degradation in FeMB degradation system are different from others. PCE was mainly via hydrogenolysis degraded to trichloroethylene （TCE）, then TCE via hydrogenolysis to 1,1-dichloroethylene （1,1-DCE） and then 1,1-DCE viaα-elimination to ethylene. The integrated technique combining the iron and the microbial community showed better degradation efficiency than the others; it may be viewed as an environmentally desirable remediation.The advection-dispersion transport model coupling amended dual-mode adsorption model and pseudo-first-order kinetic reaction model was developed to simulate the transport process of PCE in modeling column for the FeMB remediation, the simulated transport process accorded with the observed very well. The model can be used to describe the environmental behaviors and forecast the fate of PCE in groundwater.更多还原