EAGER: Deterioration of Stormwater Filter Media by Deicing Salts: X-ray Micro Computed Tomography (µCT)

1548901

Kakuturu

This project proposes to explore an innovative use of x-ray micro computed tomography to investigate the effect of deicing salt on stormwater filter media. Stormwater filters are critical in preventing floods and protecting the environment by allowing stormwater to infiltrate to ground and entrapping the pollutants. Prior studies have raised concerns about the deicing salts' role in deterioration of stormwater filter media and environmental contamination. This project outlines a plan to conduct flow tests, using NaCl as a deicing salt, and to evaluate the pre- and post-salt-application pore structures' in stormwater filter media using x-ray micro computed tomography.

This project will explore x-ray micro computed tomography to examine stormwater filter media pore structure. The data will be analyzed using computer simulations for developing an understanding of deterioration, a critical research need. Two hypotheses are to be tested: (1) There is a statistical correlation between 'flow rate' and 'ratio of active porosity to total porosity.' (2) Given that the total amount of NaCl is similar, differences in stormwater filter media degradation (the ratio of 'active porosity' to 'total porosity') will not be significantly different at three different NaCl concentrations. The results of this research will address two scientific questions: (1) How does the pore structure of a SFM change due to application of NaCl? (2) Is there a relationship between the 'ratio of active porosity to total porosity' and infiltration rate? This project's goal is to explore and test this radically different research approach for addressing the critical need to scientifically understand the deterioration of stormwater filter media. The PI proposes to achieve this goal by using state-of-the-art of x-ray micro computed tomography, and a combination of discrete element and lattice Boltzmann methods simulations. This approach has demonstrated success in other research fields, for example, medicine, biology, agriculture, geology, industrial, etc. The PI has successfully conducted a pilot study using x-ray micro computed tomography for visualization of SFMs' pore structure. The same samples will be scanned before and after salt application. The three dimensional image data will be used for constructing three dimensional pore structures of stormwater filter media. The three dimensional pore spaces will be used in morphological analysis and model simulations. Results (distribution of porosity, gradients, etc.) will help us in understanding the mechanism of SFM deterioration. This project will establish x-ray micro computed tomography as a suitable method for studying porous media, and will transform the scientific understanding of different porous media.