InterPore2025

Connecting continuum REV-scale models with laboratory and field experiments of Soil-Aquifer Treatment (SAT) systems

21 May 2025, 10:05

1h 30m

Poster Presentation (MS05) Microbial Dynamics in Porous Media: Advances in Biofilms, Biogeochemistry, and Biotechnology Poster

Speaker

Edwin Saavedra Cifuentes (Northwestern University)

Description

Soil-Aquifer Treatment (SAT) is a well-established water storage and tertiary wastewater treatment strategy with low energy requirements. For example, effluent from the Shafdan Wastewater Treatment Plant (WWTP) in Israel is processed through SAT systems to improve water quality before its reuse for crop irrigation. SAT systems operate by allowing water to infiltrate the subsurface, where microbial communities metabolize organic carbon, nitrogen species, and other constituents and pollutants transported in the water.

SAT operation is limited by bioclogging, as microbial growth, supported by nutrient-rich effluent from WWTPs, fills soil voids with biomass, reducing the system's infiltration capacity. Bioclogging is reversed through alternating drying periods, which interrupt nutrient delivery, replenish oxygen, and desiccate biofilms. However, this approach significantly reduces the total volume of water treated. An alternative strategy being tested in field experiments is active air injection into the subsurface (Air-SAT), which has shown the potential to allow greater effluent infiltration than traditional flooding-drying regimes (Arad et al., 2023).

In parallel with laboratory and field experiments in the Shafdan WWTP, we developed a 3D finite-volume modeling tool to characterize SAT functioning at the REV scale. This model is employed to optimize wetting-drying strategies by integrating infiltration, unsaturated flow, reactive transport, and microbial growth, while accounting for changes in hydraulic conductivity caused by bioclogging (Saavedra Cifuentes et al., 2024). A simplified constraint on the dissolved oxygen field is incorporated into the model to simulate Air-SAT applications.

This presentation will showcase data from various SAT experiments alongside results of our numerical models, focusing on how the latter has helped to test additional hypotheses and extend our understanding of processes governing SAT function. We will explore alternatives for characterizing air injections in the same modeling environment and discuss the extent to which we can capture complex air injection mechanics in our continuum model. Finally, we will examine the trade-offs between achieving fast numerical solutions to inform field applications while sacrificing pore-scale resolution due to the generalization inherent in REV-scale modeling.

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References:

Arad, I., Ziner, A., Ben Moshe, S., Weisbrod, N., & Furman, A. (2023). Improving soil aquifer treatment efficiency using air injection into the subsurface. In Hydrology and Earth System Sciences (Vol. 27, Issue 13, pp. 2509–2522). Copernicus GmbH. https://doi.org/10.5194/hess-27-2509-2023

Saavedra Cifuentes, E., Furman, A., Rosenzweig, R., and Packman, A. I.: Continuum modeling of bioclogging of soil aquifer treatment systems segregating active and inactive biomass, Hydrol. Earth Syst. Sci. Discuss. [preprint], https://doi.org/10.5194/hess-2024-251, in review, 2024.