A Transport-Rate-Limited Numerical Model for Simulating Cell Growth and Biodegradation Rates in Porous Soil and Rock

申请方建议审查水文地质系统中强化生物修复的数值模拟专题。这将涉及扩展多相组成的数值模型CompFlow BioF，以包括运输和反应速率限制的方法来模拟电子从基质到生物质的化学计量交换，最后到土壤空隙空间内的受体。该生物降解制剂的目的是能够模拟脉冲空气喷射的高度瞬态过程，以刺激汽油源区的好氧生物降解。问题的几何形状涉及一个饱和的多孔介质或离散断裂的多孔岩石含水层，其中多组分汽油混合物从位于渗流区的地下储罐泄漏。汽油形成轻的非水相（LNAPL），其随后在地下水位上流动并变得漂浮，随后汽油组分（基质）发生传质和平流扩散运输到原始地下水中。由于在地下水中发生了汽油组分的含水层规模的质量传输，因此KLA导出了电子供体和受体从多孔介质的空隙空间内的水相到附着于多孔介质的生物质上的质量传输的传质系数。然后，该模型从电子供体（汽油组分作为底物）到电子受体（有氧降解的氧气）的电子化学计量平衡反应，并在增加生物质浓度的同时去除溶解的底物。生物反应在各种限速条件下发生，包括由于以下三个过程：电子供体限制的传质、电子受体限制的传质和由于生物质促进电子传递过程的能力而导致的微生物密度限制。运输和反应速率限制的方法允许连续过渡到三个过程中的任何一个限制生物反应过程，并最终限制羽流尺度生物降解的时空演变。这种方法还支持牛顿迭代的二次收敛，允许CompFlow BioF多相组成模型模拟真实世界规模的含水层问题。因此，本提案的结果将有助于建立所需的知识库，以便在包括大气喷射和水相营养物注入等强化反应技术的条件下，对需氧和厌氧生物降解进行多相多组分模拟。这一结果将使模拟增强生物降解技术的设计，实施，并可能优化污染物羽补救系统。

The applicant proposes to examine the topic of the numerical simulation of enhanced bioremediation in hydrogeological systems. This will involve extending the multi-phase compositional numerical model CompFlow BioF to include a transport and reaction rate limited approach to simulate the stoichiometric exchange of electrons from the substrate, to the biomass, and finally to the acceptor within the void space of the soil. The objective of this biodegradation formulation is to be able to simulate the highly transient processes of pulsed air sparging to stimulate aerobic biodegradation of gasoline source zones. The problem geometry involves a variably saturated porous media or discretely fractured porous rock aquifer in which a multi-component gasoline mixture is leaked from an underground storage tank located within the vadose zone. The gasoline forms a light-non-aqueous phase (LNAPL) which subsequently mobilizes and becomes buoyant on the water table, with subsequent mass transfer and advective-diffusion transport of the gasoline components (substrate) into the pristine groundwater. As aquifer-scale mass transport of the gasoline components occurs in the groundwater, a KLA derived mass transfer coefficient for the mass transport of electron donor and acceptor from the aqueous phase within the void space of the porous media onto the biomass that is attached to the porous media. The model then reacts a stoichiometric balance of electrons from the electron donor (gasoline components as substrate) to the electron acceptor (oxygen for aerobic degradation) and removes dissolved substrate while increasing the biomass concentration. Bioreactions occur under various rate-limiting conditions including due to the following three process: electron donor-limiting mass transfer, electron acceptor-limiting mass transfer, and microbial density-limiting due to the capacity of the biomass to facilitate the electron transfer process. The transport and reaction rate limited approach allow for a continuous transition to whichever of the three processes is limiting the bioreaction process and ultimately the spatial-temporal evolution of the plume-scale biodegradation. This approach also supports quadratic converge of the Newton iteration allowing the CompFlow BioF multi-phase compositional model to simulate real-world scale aquifer issues. The outcome of this proposal is therefore to contribute to the knowledge base required for the multi-phase multi-component simulation of aerobic and anaerobic biodegradation under conditions that include technologies to enhance reactions such as atmospheric air sparging and aqueous phase nutrient injection. This outcome will enable simulation of enhanced biodegradation technologies to design, implement, and potentially optimize contaminant plume remediation systems.