Seetha N, Mohan Kumar M S, Majid Hassanizadeh S
Department of Civil Engineering, Indian Institute of Science, Bangalore, 560012, India.
Department of Civil Engineering, Indian Institute of Science, Bangalore, 560012, India; Indo-French Cell for Water Sciences, Indian Institute of Science, Bangalore, 560012, India.
J Contam Hydrol. 2015 Oct;181:82-101. doi: 10.1016/j.jconhyd.2015.01.002. Epub 2015 Jan 28.
A mathematical model is developed to simulate the co-transport of viruses and colloids in unsaturated porous media under steady-state flow conditions. The virus attachment to the mobile and immobile colloids is described using a linear reversible kinetic model. Colloid transport is assumed to be decoupled from virus transport; that is, we assume that colloids are not affected by the presence of attached viruses on their surface. The governing equations are solved numerically using an alternating three-step operator splitting approach. The model is verified by fitting three sets of experimental data published in the literature: (1) Syngouna and Chrysikopoulos (2013) and (2) Walshe et al. (2010), both on the co-transport of viruses and clay colloids under saturated conditions, and (3) Syngouna and Chrysikopoulos (2015) for the co-transport of viruses and clay colloids under unsaturated conditions. We found a good agreement between observed and fitted breakthrough curves (BTCs) under both saturated and unsaturated conditions. Then, the developed model was used to simulate the co-transport of viruses and colloids in porous media under unsaturated conditions, with the aim of understanding the relative importance of various processes on the co-transport of viruses and colloids in unsaturated porous media. The virus retention in porous media in the presence of colloids is greater during unsaturated conditions as compared to the saturated conditions due to: (1) virus attachment to the air-water interface (AWI), and (2) co-deposition of colloids with attached viruses on its surface to the AWI. A sensitivity analysis of the model to various parameters showed that the virus attachment to AWI is the most sensitive parameter affecting the BTCs of both free viruses and total mobile viruses and has a significant effect on all parts of the BTC. The free and the total mobile viruses BTCs are mainly influenced by parameters describing virus attachment to the AWI, virus interaction with mobile and immobile colloids, virus attachment to solid-water interface (SWI), and colloid interaction with SWI and AWI. The virus BTC is relatively insensitive to parameters describing the maximum adsorption capacity of the AWI for colloids, inlet colloid concentration, virus detachment rate coefficient from the SWI, maximum adsorption capacity of the AWI for viruses and inlet virus concentration.
建立了一个数学模型，用于模拟稳态流动条件下非饱和多孔介质中病毒和胶体的共运移。采用线性可逆动力学模型描述病毒与可移动和不可移动胶体的附着。假设胶体运移与病毒运移解耦；也就是说，我们假设胶体不受其表面附着病毒的影响。使用交替三步算子分裂方法对控制方程进行数值求解。通过拟合文献中发表的三组实验数据对模型进行验证：（1）Syngouna和Chrysikopoulos（2013年）以及（2）Walshe等人（2010年），均为饱和条件下病毒和粘土胶体的共运移，以及（3）Syngouna和Chrysikopoulos（2015年）用于非饱和条件下病毒和粘土胶体的共运移。我们发现在饱和和非饱和条件下，观测到的和拟合的突破曲线（BTCs）之间有很好的一致性。然后，利用所建立的模型模拟了非饱和条件下多孔介质中病毒和胶体的共运移，目的是了解各种过程对非饱和多孔介质中病毒和胶体共运移的相对重要性。与饱和条件相比，在非饱和条件下，胶体存在时病毒在多孔介质中的保留率更高，原因如下：（1）病毒附着在气水界面（AWI）上，以及（2）胶体与附着在其表面的病毒在AWI上的共沉积。对模型对各种参数的敏感性分析表明，病毒在AWI上的附着是影响游离病毒和总可移动病毒BTCs的最敏感参数，并且对BTC的所有部分都有显著影响。游离病毒和总可移动病毒的BTCs主要受描述病毒在AWI上的附着、病毒与可移动和不可移动胶体的相互作用、病毒在固水界面（SWI）上的附着以及胶体与SWI和AWI相互作用的参数影响。病毒BTC对描述AWI对胶体的最大吸附容量、入口胶体浓度、病毒从SWI的脱离速率系数、AWI对病毒的最大吸附容量和入口病毒浓度的参数相对不敏感。
