| 运用STOMP数值模拟器进行多空介质中尿素水解以及方解石沉淀数值模拟 |
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| 引用本文： | 郭娈靖,Hai Huang,Bill X.Hu.运用STOMP数值模拟器进行多空介质中尿素水解以及方解石沉淀数值模拟[J].地学前缘,2010,17(6):117-133. |
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| 作者姓名： | 郭娈靖 Hai Huang Bill X.Hu |
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| 基金项目： | 美国能源部地下生物化学研究部门科学重点支持项目 |
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| 摘 要： | 遍布于美国能源部所辖野外场地的地下放射性核素和痕量金属污染对美国能源部的长期监管职能提出了最严峻的挑战。目前较有前景的一个原地固化污染物方法是利用尿素酶催化尿素水解,进而推动方解石沉淀及与之共同沉淀。运用STOMP数值模拟器实施一系列反应性溶质数值模拟来研究系统中水流、运移、反应与反应导致的介质性质变化之间的紧密的非线性耦合,并在研究中系统性增加反应系统的复杂度和物理-化学的非均质性以考察模拟效果。通过调整反应速率表达式中尿素酶浓度和沉淀反应常数,对尿素水解和方解石沉淀速率进行了敏感度分析。结果显示:尿素水解速率是矿物沉淀总量的决定性因素,沉淀物的空间分布既取决于水解速率也取决于沉淀速率;在一维水流柱6个空隙体积的时间段模拟中,观察到了5%的最大空隙度减少;当二维模拟中考虑一个低渗透性包裹体时,被改变的流场重新对生成的沉淀组成物进行了分布,形成了扭曲的反应锋面。模拟结果也显示沉淀在低渗透性区域边界上形成,这说明位于这个区域里面的污染物可能被囊裹而从流线中被隔离起来。
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| 关 键 词： | 数值模拟 原地污染治理 尿素水解 方解石沉淀 STOMP |
NUMERICAL SIMULATIONS OF UREA HYDROLYSIS AND CALCITE PRECIPITATION IN POROUS MEDIA USING STOMP |
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| Luanjing Guo,Hai Huang,Bill X.Hu.NUMERICAL SIMULATIONS OF UREA HYDROLYSIS AND CALCITE PRECIPITATION IN POROUS MEDIA USING STOMP[J].Earth Science Frontiers,2010,17(6):117-133. |
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| Authors: | Luanjing Guo Hai Huang Bill XHu |
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| Abstract: | Subsurface radionuclide and trace metal contaminants throughout the U.S. Department of Energy (DOE) complex pose one of DOE's greatest challenges for long-term stewardship. One promising in situ immobilization approach of these contaminants is engineered mineral (co)precipitation of calcite driven by urea hydrolysis that is catalyzed by enzyme urease. The tight nonlinear coupling among flow, transport, reaction and reaction-induced property changes of media of this approach was studied by reactive transport simulations with systematically increasing level of complexities of reaction network and physical/chemical heterogeneities using a numerical simulator named STOMP. Sensitivity studies on the reaction rates of both urea hydrolysis and calcite precipitation are performed via controlling urease enzyme concentration and precipitation rate constant according to the rate models employed. We have found that the rate of ureolysis is a dominating factor in the amount of precipitated mineral;however, the spatial distribution of the precipitates depends on both rates of ureolysis and calcite precipitation. A maximum 5% reduction in the porosity was observed within the simulation time period of 6 pore volumes in our 1-dimensional (1D) column simulations. When a low permeability inclusion is considered in the 2D simulations, the altered flow fields redistribute mineral forming constituents, leading to a distorted precipitation reaction front. The simulations also indicate that mineral precipitation occurs along the boundary of the low permeability zone, which implies that contaminants in the low permeability zone could be encapsulated and isolated from the flow paths. |
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| Keywords: | numerical simulation in situ remediation urea hydrolysis calcite precipitation STOMP |
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