【作者】 陆建生；

【导师】 仵彦卿；

【作者基本信息】 上海交通大学 ， 环境科学， 2008， 硕士

【摘要】 研究氯代溶剂在含水层中的迁移转化规律,对评价其对环境的影响、预测其行为规律及确定相应的修复策略有着重要意义。通过对比三氯乙烯(TCE)在石英砂和细砂中的批量吸附试验结果,建立了描述表面吸附与分配作用的Linear-Langmuir-Freundlich(LLF)等温非线性吸附模型。该模型能最佳地描述TCE单溶质在细砂中的非线性等温吸附规律。但砂柱试验结果表明,最佳的吸附模式为Langmuir模型,即由批试验与柱实验得到的吸附模式不同,这表明在运移模型中应用非平衡吸附理论需慎重。根据实验结果和模型反演参数确定TCE在多孔介质中运移的一维非线性吸附-对流-扩散模型。应用BP神经网络研究四氯乙烯(PCE)和TCE的竞争吸附关系,建立了在BP神经网络基础上的多溶质系统下多组分竞争性吸附-对流-扩散模型。金属降解PCE和TCE的实验表明,零价锌(Zn(0))降解有机物最有效。假设各化学反应符合准一级动力学,建立多级链式平行反应数学模型,用混合函数遗传算法进行动力学参数的反演。确定主要反应路径为PCE→TCE→t-DCE→C2H2→C2H4和PCE→C2Cl2→t-DCE→C2H2→C2H4。最终有94.77%的PCE转化为C2H4,5.23%转化成氯乙烯(VC)。Zn(0)降解TCE时,各物质主要反应类型和路径与前述有所差别,表明PCE,TCE及各产物之间相互影响。根据反应柱试验结果,建立了多组分反应性溶质的一维非线性吸附-对流-扩散-降解模型,应用遗传算法进行模型参数反演,确认TCE,c-DCE, t-DCE的不同吸附模式及其时空分布规律,进一步用于渗透反应墙厚度的最优化设计。更多还原

【Abstract】 It is significant to investigate the transport of chlorinated solvent in porous media for analysis of natural attenuation and remediation of groundwater pollution. Based on the batch test of trichloroethylene (TCE) adsorbed to fine sand and to quartz, the Linear-Langmuir-Freundlich (LLF) model, which can reveal the mechanisms of adsorption and partition, was established through fitted curves with calculated and tested values. In the sandy column experiments, Langmuir isotherm model could describe best the adsorption mechanisms of TCE. The nonlinear adsorption-advection- diffusion model, which reveals the transport mechanisms of TCE in porous media, was established based on the experiments and the inversed parameters with genetic algorithm. The competition adsorption between perchlorethylene(PCE) and TCE was studied by BP Neural Network, the multicomponent competitive adsorption-advection-diffusion model was established on the base of BP Neural Network.In many kinds of metals which was used to degrading PCE and TCE, the Zn(0) was most effective. Through the batch experiment of reductive degradation of PCE using Zn(0), the mathematical model of multi-chain and parallel reaction was established assuming each reaction fitting pseudo first order kinetic reaction. The kinetic parameters were inversed with hybrid function generic algorithm. The primary reaction pathway was PCE→TCE→t-DCE(trans-dichloroethylene)→C2H2→C2H4 and PCE→C2Cl2→t-DCE→C2H2→C2H4. At the end of tests 94.77% of PCE was degraded to C2H4, 5.23% to vinyl chloride (VC). Comparison the degradation of TCE by Zn(0), the primary pathways and reaction model were different from the degradation PCE by Zn(0), so there may be interactions among PCE, TCE and intermediates.In the reaction column, the 1-D nonlinear adsorption-advection-diffusion-reaction model of multi-component reaction solute was established. According to the experiment result, the model parameters were inversed by using generic algorithm. The different adsorption models and the spatio-temporal distribution of TCE,c-DCE and t-DCE were confirmed. At last the thickness of PRB can be designed by using the nonlinear adsorption-advection-diffusion-reaction model.更多还原