Dissertation Proposal - Md Khorshed Alam

Coupled Multidimensional Seepage and Transport Models to Simulate Fate and Transport of PFAS Through Soil

Presented by Md Khorshed Alam, Computational Math Science and Engineering emphasis

Hybrid presentation: Attend in-person at Environmental Research Building Room 3127 or register to attend online via Zoom

Abstract

Per- and polyfluoroalkyl substances (PFAS) are a class of extremely stable, man-made chemicals well-known for their heat and moisture resistance. As a result, manufacturers utilize them in the production of a wide range of products, including aqueous film-forming foams (AFFF) for firefighting. The release of these chemicals into surface water, soils, sediments, and groundwater occurs when they are introduced into the environment through various means, such as being deposited in landfills or being used in firefighting foams and related products. This poses significant health risks to humans and other animals. Having a comprehensive understanding of the fate and transport of PFAS is of utmost importance in advancing the development of remediation strategies and minimizing pertaining hazards. Researchers have modeled the behavior of PFAS in soil environments using a variety of computational tools and numerical techniques, and they have made great strides in comprehending the transport mechanism. Despite a great number of modeling and experimental investigations of the transport of PFAS and its effects, various contributing factors are still poorly understood because of their complex nature in the environment and the heterogeneity of porous mediums like soil. Therefore, in this work, we aim to present numerical simulation frameworks for further understanding the impact of factors like lateral and longitudinal mechanical dispersion, non-diagonal tortuosity tensor, variable degree of saturation-dependent air-water interfacial areas, and biological and chemical decay on the fate and transport of PFAS through anisotropic soil mediums, especially when soil stratigraphy is not axisymmetric. To carry out this goal, two-dimensional groundwater seepage and PFAS transport models will be constructed in this proposal to investigate the influence of the nature or artificially induced orientation of the soil stratigraphic plane on seepage flow and to analyze the impact of diffusion, advection, and adsorption onto the air-water and solid-phase interface mechanisms on PFAS transport through numerical simulations. This work can guide the development of multidimensional seepage and PFAS transport models and enhance understanding of the contribution of mechanical dispersion, tortuosity, varied air-water interfacial area, and degradation factors to the fate and transport of PFAS through anisotropic soil mediums by coupling them. In addition, our future endeavors include the validation of these models against experimental data for different types of soil as well as the stability of these models through sensitivity analysis. It is expected that the proposed models will help to scale down the knowledge gaps in understanding the behaviors of PFAS transport in the soil environment and help environmental engineers and scientists design effective remediation plans.

Committee

Dr. Arvin Farid, Dr. Jodi Mead, Dr. Krishna R. Reddy, Dr. Michal Kopera