有毒有机化合物在土壤水环境中生物降解过程及规律研究

Engineered biodegradation in soil-water-microbes system is an economical and effective method in degrading organic contaminants in soil. In order to guide scientifically the biodegradation operation in remediation site, it is very necessary to study its regularity extensively. Based on the mass-balance, chemical thermodynamics and chemical kinetics theories, using the methods of theoretical analysis, mathematical simulation, as well as the bench scale and pilot scale experiments, the issues concerning organic chemical biodegradation in soil-water-microbes system were studied in this research. The results obtained can be addressed as follows The concepts of bioavailability and bioactivity were proposed in this research in order to illustrate the effect of sorption on the biodegradation of organic contaminants in oil-water-microbes system. Through the theorical analysis and spherical model calculation, it is clear that the rate of biodegradation for organic chemical in soil-water-microbes system is much slower than the one in pure water phase. And the chemical overall removal rate decreases quite sensitively as sorption partition coefficient Kd increases.The effect of sequestration inside soil particle on organic chemical biodegradation in soil-water-microbes system was studied in this research. It is pointed that the mechanism of equestration comes from the strong interaction between organic contaminant and soil organic matter. The result of sequestration causes organic chemical sequestrated inside soil particle, losing its original chemical and biological activities, and hence, much less available, toxic and mobile than the "free" compounds. Based on the sequestration theory, a kinetic equation, which could quantitatively describe the sequestration inside the soil particle, was firstly proposed in this research. It should be very useful in determining the environmental acceptable endpoint in soil..Based on the mass-balance theory, a comprehensive mathematical model, which could predict organic chemical biodegradation process in remediation site, concerning the effects of diffusion, sorption/desorption, biodegradation, especially intraparticle irreversible sequestration, has been firstly developed in this research. In this model, diffusion is represented by Fick's second law, local sorption-desorption by a linear isotherm, irreversible sequestration by a pseudo-first order kinetics, and biodegradation by Monod kinetics. Numerical solutions were obtained to provide estimates of chemical concentrations. A sensitivity analysis was performed to assess the effect of several parameters on model behavior. It is noteworthy that chemical's concentrations in soil, in particle water phase, and in bulk water, which change with the disposal time, could be predicted using this model. The time needed to reach the environmental acceptable endpoint in remediation site could be predicted either. .Bench-scale low-molecular-weight organic chemical's sorption experiment in soil/water system, biodegradation experiment in pure water phase, and biodegradation experiment in soil-water-microbes system were conducted in this paper. Using the experimental data, the model parameters were evaluated and the comprehensive mathematical model was verified either. It is showed that the model is reliable in simulating low-molecular-weight organic chemical's biodegradation process in the soil-water-microbes system.Polynuclear aromatic hydrocarbons (PAHs) iodegradation process in remediation site was studied in this research. Results from a multi-year pilot-scale land treatment project for PAHs' biodegradation were evaluated in this research. The comprehensive mathematical model, which was proposed in this research, was further verified using the field experimental data. The regularities about the typical organic contaminant PAHs' biodegradation process in remediation site, such as PAHs' degradation behavior, the necessary treatment time to reach the endpoint in the system were studied and predicted in this research.Polychlorinated biphenyls (PCB

在深入研究土壤颗粒内部屏蔽反映的基础上，通过室内实验、野外实验以及野外长期实验资料的分析，建立数学模型，并进行有机物降解过程的风险分析，以研究有毒有机化合物在土壤水环境中降解可以接受的降解终点所需的时间，为科学指导和管理土地生物处理基地的工作提供决策依据。