Spatiotemporal evolution of iron and sulfate concentrations during riverbank filtration: Field observations and reactive transport modeling

Woonghee Lee; Etienne Bresciani; Seongnam An; Ilka Wallis; Vincent Post; Seunghak Lee; Peter K Kang

doi:10.1016/j.jconhyd.2020.103697

Spatiotemporal evolution of iron and sulfate concentrations during riverbank filtration: Field observations and reactive transport modeling

J Contam Hydrol. 2020 Oct:234:103697. doi: 10.1016/j.jconhyd.2020.103697. Epub 2020 Aug 5.

Authors

Woonghee Lee¹, Etienne Bresciani², Seongnam An³, Ilka Wallis⁴, Vincent Post⁵, Seunghak Lee⁶, Peter K Kang⁷

Affiliations

¹ Department of Earth and Environmental Sciences, University of Minnesota, Twin Cities, MN 55455, USA.
² Water Cycle Research Center, Korea Institute of Science and Technology, Seoul 02792, South Korea.
³ Water Cycle Research Center, Korea Institute of Science and Technology, Seoul 02792, South Korea; Department of Earth and Environmental Sciences, Korea University, Seoul 02841, South Korea.
⁴ College of Science and Engineering, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia; University of Manitoba, Winnipeg, MB R3T 5V6, Canada.
⁵ Federal Institute for Geosciences and Natural Resources (BGR), Stilleweg 2, 30655 Hannover, Germany.
⁶ Water Cycle Research Center, Korea Institute of Science and Technology, Seoul 02792, South Korea; Division of Energy & Environment Technology, KIST School, Korea Institute of Science and Technology, Seoul 02792, South Korea. Electronic address: seunglee@kist.re.kr.
⁷ Department of Earth and Environmental Sciences, University of Minnesota, Twin Cities, MN 55455, USA; Saint Anthony Falls Laboratory, University of Minnesota, Twin Cities, MN 55414, USA. Electronic address: pkkang@umn.edu.

PMID: 32836105
DOI: 10.1016/j.jconhyd.2020.103697

Abstract

Riverbank filtration is a commonly-used technology that improves water quality by passing river water through aquifers. In this study, a riverbank filtration site in Busan, South Korea, was investigated to understand the spatiotemporal evolution of high iron and sulfate concentrations observed in the riverbank-filtered water. Discrepancies between the nonreactive transport results and field measurements suggest that iron-sulfate-related geochemical reactions play a major role in the spatiotemporal evolution of the hydrochemical properties. Pyrite oxidation was hypothesized to be the main process driving the release of iron and sulfate. To test this hypothesis, a reactive transport model was developed, that implemented pyrite oxidation as a kinetic process and subsequent ferrous iron oxidation and ferric iron precipitation as equilibrium processes. The model accurately captured the temporal evolution of sulfate; however, iron concentrations were underestimated. Sensitivity tests revealed that adjusting reaction constants significantly improved the prediction of iron concentrations. The results of this study suggest that pyrite oxidation can affect the hydrochemistry of riverbank-filtered water and highlight the potential limitations of using theoretical reaction constants in field modeling applications.

Keywords: Groundwater; Iron and Sulfate; Pyrite oxidation; Reaction constant; Reactive transport modeling; Riverbank filtration.

MeSH terms

Filtration
Groundwater*
Republic of Korea
Sulfates / analysis
Water Pollutants, Chemical* / analysis
Water Quality

Substances

Sulfates
Water Pollutants, Chemical