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Enhancement of in situ bioremediation by pneumatic fracturing: Field demonstration, laboratory studies and systems modeling.

机译：通过气力压裂增强原位生物修复：现场演示，实验室研究和系统建模。

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Currently available remediation options for the decontamination of pollutants in low permeability formations are expensive and time-consuming. The goal of this research was to design, develop and implement integrated pneumatic fracturing/bioremediation technology at pilot-scale. Specific objectives included quantification of the underlying adsorption, diffusion and biodegradation phenomena in detail using laboratory batch and column experiments. A mathematical model was developed for the design of the integrated technology and to perform sensitivity analysis of field process parameters on contaminant removal rates.; The integrated system was applied at field pilot-scale to create artificial fractures in a BTX-contaminated geologic formation, resulting in enhanced subsurface air flow and transport rates. Following the fracturing, the system was used to inject biological amendments directly into the formation to stimulate biodegradation. Results indicated that fracturing increased subsurface permeability by an average of 36 times. Information gained from periodic vapor sampling indicated that the production of carbon dioxide was enhanced following subsurface injections, due to increased biological activity. Following a lag period, the methanogens became active and an increase in methane production was also observed. After one year of process operation and monitoring, soil samples obtained from the site indicated a 79% reduction in BTX concentrations, over 85% of which was assigned to biodegradation.; Laboratory column experiments for simulation of the fracture interface were conducted. These studies provided rate and kinetic information on the aerobic and denitrifying biodegradation processes in the presence of coupled diffusion and reaction. A transport model incorporating the phase partitioning, diffusion and reaction phenomena was developed and validated. Experiments involving solid-liquid adsorption, vapor diffusion and biodegradation were conducted to obtain model parameters. These parameter values were used in a diffusion model which was compared against the laboratory column results.; A design model to predict the fate and transport of solute and gaseous electron acceptors in fractured soil beds was developed and validated. The model accounted for vapor diffusion, vapor-liquid partitioning, solute adsorption and biodegradation in the soil bed, and vapor convection in the fracture region. Simulation studies were performed to examine the effect of several field process parameters such as extraction flow rates, solute biodegradation rates and fracture interval on relative rates of contaminant removal. The model was also capable of predicting the bed oxygen diffusion profiles; thus, providing information on the ability of the formation to support aerobic biodegradation.
机译：对于低渗透性地层中污染物的去污，目前可用的补救措施既昂贵又费时。这项研究的目的是在中试规模设计，开发和实施集成的气动压裂/生物修复技术。具体目标包括使用实验室分批和色谱柱实验详细量化潜在的吸附，扩散和生物降解现象。开发了用于集成技术设计的数学模型，并执行了现场过程参数对污染物去除率的敏感性分析。该集成系统以现场试验规模应用，在受BTX污染的地质构造中形成了人工裂缝，从而提高了地下空气流量和传输速率。压裂之后，使用该系统将生物修正剂直接注入地层中以刺激生物降解。结果表明，压裂平均提高了地下渗透率36倍。从定期蒸汽采样中获得的信息表明，由于生物活性的提高，地下注入后二氧化碳的产量增加了。滞后一段时间后，产甲烷菌变得活跃起来，甲烷产量也有所增加。经过一年的过程操作和监控，从现场获得的土壤样品表明BTX浓度降低了79％，其中超过85％的生物降解被指定为生物降解。进行了模拟断裂界面的实验室柱实验。这些研究提供了在耦合扩散和反应存在下好氧和反硝化生物降解过程的速率和动力学信息。开发并验证了包含相分配，扩散和反应现象的传输模型。进行了涉及固液吸附，蒸气扩散和生物降解的实验以获得模型参数。这些参数值用于扩散模型，并与实验室色谱柱结果进行比较。建立并验证了预测破裂土壤床中溶质和气态电子受体的命运和运移的设计模型。该模型考虑了蒸汽扩散，气液分配，溶质在土壤床中的吸附和生物降解以及裂缝区域中的蒸汽对流。进行了仿真研究，以检验几个现场过程参数（例如萃取流速，溶质生物降解率和断裂间隔）对污染物去除率的影响。该模型还能够预测床氧扩散曲线。因此，提供有关地层支持需氧生物降解能力的信息。

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