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

申请人提议审查水文地质系统强化生物修复的数值模拟专题。这将涉及将多相组成数值模型CompFlow BioF扩展到包括传输和反应速率限制的方法，以模拟电子从基质到生物体，最后到土壤空隙空间内的接受者的化学计量交换。这种生物降解配方的目的是能够模拟脉冲喷气的高度瞬变过程，以刺激汽油源区的好氧生物降解。问题的几何结构涉及可变饱和的多孔介质或离散的裂隙多孔岩石含水层，其中多组分汽油混合物从位于包气带内的地下储油罐泄漏。汽油形成轻非水相(LNAPL)，随后流动并浮在地下水位上，随后汽油组分(底物)的质量传递和平流扩散输送进入原始地下水。当汽油组分在地下水中发生含水层尺度的质量传输时，KLA导出了电子供体和受体从多孔介质空隙空间内的水相到附着在多孔介质上的生物体的质量传输的传质系数。然后，该模型将电子供体(汽油成分作为底物)到电子受体(用于好氧降解的氧气)之间的电子进行化学计量平衡，并在增加生物质浓度的同时去除溶解的底物。生物反应在不同的速率限制条件下发生，包括以下三个过程：电子供体限制传质，电子受体限制传质，以及由于生物质促进电子传递过程的能力而限制微生物密度。传输和反应速率限制方法允许连续过渡到限制生物反应过程的三个过程中的任何一个，并最终限制羽流规模的生物降解的时空演变。该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，这项提议的结果是有助于建立所需的知识库，以便在包括大气喷气和水相养分注入等强化反应的技术的条件下，对好氧和厌氧生物降解进行多相多组分模拟。这一成果将使增强生物降解技术的模拟成为可能，以设计、实施并可能优化污染物羽流修复系统。

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.