(357f) Micro and Macro-Heterogeneities Effects on Transport of Pollutants in Porous Media: Fundamental Modeling Aspects

Soils are very complex porous media with a variety of scales playing a role on solutes and contaminants transport. Complete fundamental understanding about transport in complex porous media, such as soils, is far to be complete. Experimental approaches when an electrical-field-based technique is applied in homogeneous porous media are commonly reported in the literature. However, there are few modeling studies on this field to predict the role of multiple scales and driving forces on the soil-cleaning efficiency. Regarding heterogeneous porous media, where heterogeneities at the micro and macro-scale are included are in general difficult to find in the literature. Based on this motivation, this study attends to develop a more effective, systematic, and predictive description of transport of contaminants under removal operations for soils. Here, the porous structure of a soil is described by idealized micro-capillaries of a single dimension; which change both their orientation and geometry in the soil matrix. Therefore, Micro-heterogeneities will be analyzed by switching two micro-capillary geometries and assessing their impact on contaminant transport. By using an Area Averaging Approach the transport of a contaminant in micro-capillaries is scaled-up to a macro-transport equation within the capillary scale where the geometry changes will be assessed. In addition, the role of macro-heterogeneities is described by including gravity effects that depends on the capillaries inclination angle. Preliminary results show effective parameters varying according to micro and macro-heterogeneities as well as  operating conditions. These results show an important effect of macro-heterogeneities on the effective parameters and averaged species concentration profile.  Important outcomes from this study include, for example, cleaning soil times, and relevance of porous media structure; useful for technology developments such as site selection for waste disposal, and geo-membranes design.