【作者】 杨乐巍；

【导师】 李鑫钢；

【作者基本信息】 天津大学 ， 材料学， 2006， 硕士

【摘要】 土壤气相抽提(Soil Vapor Extraction, SVE)是用于修复挥发性有机物污染不饱和区土壤的一种新兴环境技术,其有效性在许多实验和现场测试中均被证实。国内主要停留在实验室研究阶段,对于土壤污染调查及现场试验研究不够,工程化应用问题急待解决。本文在此背景下,通过探讨现场SVE技术方法和过程参数分析,以现场试验为主,系统分析了SVE原位修复中的流体力学问题,对该过程中的传质现象和生物降解也做了一定研究。通过对土壤区域调查和场址评估,确定了现场SVE的设计和操作条件。拟选试验场址土壤为天津地区典型粘性土壤,其地下水水位埋藏较浅,具备现场SVE修复研究的可行性。采用常规土工实验方法和激光粒度分析方法,研究了现场各层土壤的主要物性参数。通过一维土柱通风实验,测定了现场具有代表性的土壤第二层的渗透性质,确定了SVE原位修复中的重要参数——空气相对渗透率与水饱和度的关系。在现场土壤调查分析以及土柱实验基础上,设计并建立了SVE试验装置、抽提及监测井系统。通过速率步进法确定了气泵的工作特性曲线及SVE系统曲线,获得了本场地SVE气相抽提能力数据。以单井抽提系统为研究对象,研究了土壤中气相的压力分布及流场,确定了现场SVE抽提压力影响半径及土壤的空气渗透性等重要参数。采用现场空气呼吸试验获得了二氧化碳浓度本底值及其变化趋势,进而考虑了SVE的生物强化过程。建立了现场SVE对单组分污染物(正己烷)去除的传质试验,研究了通风体系中污染物的传质机理和通风过程地下水提升的影响。气相流动原理及污染物传质机理分析探讨,建立了二维轴对称流动模型,并借助AIRFLOW/SVE软件进行了数值求解。将模拟结果与试验结果进行了分析验证,模拟结果与试验结果吻合良好。更多还原

【Abstract】 Soil vapor extraction (SVE) is a rising environmental technology for unsaturated soils contaminated with volatile organic compounds (VOCs). Its effectiveness has been demonstrated in laboratory and field tests. The study of SVE technology is still stayed at laboratory stage in domestic and the contamination survey and research of oilfield is deficient. Engineering applications of soil remediation is not taken into account.This paper is to systematically explore SVE in respects of technical methods and procedure parameter analysis mainly in field study of in-situ remediation vapor flow item, elementary mass transfer and biodegradation study involved at the same time. Soil and groundwater condition of SVE site is ascertained through soil survey and field evaluation. The main soil style is representative clay which typically distributes in Tianjin region. Shallow water table makes the field experiments feasible for in-situ SVE remediation. The main soil parameters are achieved according to regular civil engineering experimental method and laser particle size analysis at laboratory. One-dimensional column venting experiments of muddy clay simulating the SVE field is used to measure permeability properties of the representative soil of layer②and ascertain the relationship between relative permeability and saturation of air and water.On the basis of soil survey analysis and soil column study, Soil Vapor Extraction Equipment installation and SVE extracting and monitoring system are designed and built-up. The Stepped-rate procedure is used to test performance characteristics curve of vortex pump and curve of SVE system to achieve data of extraction ability of this SVE system. Take single-well extraction system as the study object, gaseous pressure distribution and flow field in the soil are studied to ascertain some important parameters such as the radius of influence of SVE extracting pressure and air permeability of the soil.Site air respiration experiment is taken place to test the local blank value of CO2 and its changing trend SVE bio-strengthen process is thereafter considered. Monocomponent contaminant (n-hexane) removing mass transfer experiment of site SVE system is founded and the contaminant mass transfer mechanism of SVE system and water table rising influenced by venting process are studied.更多还原