首页|Infiltration of secondary treated wastewater into an oxic aquifer: Hydrochemical insights from a large-scale sand tank experiment

Infiltration of secondary treated wastewater into an oxic aquifer: Hydrochemical insights from a large-scale sand tank experiment

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  • NSTL
  • Elsevier
© 2024To mitigate groundwater level decline, managed aquifer recharge (MAR) with secondary treated wastewater (STWW) is increasingly considered and implemented. However, the effectiveness and potential risks of such systems need evaluation prior to implementation. In this study, we present a large-scale sand tank experiment to analyse processes related to the infiltration of real STWW through the vadose zone and subsequent mixing with oxic native groundwater. The varying composition of STWW from 15 infiltration cycles over six months of operation and the retention times were the main drivers of the observed processes, which were characterized by a wide range of analytical techniques such as in situ high-resolution oxidation–reduction potential (ORP) measurements, closed mass balances of solutes, characterization of dissolved organic carbon (DOC), stable nitrate isotopes analysis, as well as numerical flow and transport modelling. Depending on the composition and infiltration rates of the STWW, both nitrification and denitrification could be observed, even simultaneously at different locations in the tank. Furthermore, due to the variability of the real STWW we observed enhanced arsenic mobilisation during times of elevated phosphate concentrations of the infiltrating STWW. Additionally, uranium was mobilised in our experimental system via carbonate mineral dissolution caused by the infiltrating STWW which was undersaturated of calcite for all infiltration cycles. Overall, our results showed the importance of conducting studies with waters of complex matrix, such as real STWW, and considering mixing with groundwater to assess the full range of possible processes encountered at MAR field sites.

Capillary fringeManaged aquifer rechargeNutrientsSoil aquifer treatmentTrace metals

Horovitz M.、Leitao T.E.、Munoz-Vega E.、Knoller K.、Schuth C.、Schulz S.

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Hydraulics and Environment Department Laboratório Nacional de Engenharia Civil – LNEC||Hydraulics and Environment Department Laboratório Nacional de Engenharia Civil–LNECHydraulics and Environment Department Laboratório Nacional de Engenharia Civil–LNEC||Institute of Applied Geosciences Technische Universität Darmstadt||

Hydraulics and Environment Department Laboratório Nacional de Engenharia Civil – LNEC

Institute of Applied Geosciences Technische Universität Darmstadt

Institute of Applied Geosciences Technische Universität Darmstadt||Department of Catchment Hydrology Helmholtz Center for Environmental Research – UFZ

Institute of Applied Geosciences Technische Universität Darmstadt||Water Resources Management Division IWW Water Centre

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2024

10.1016/j.watres.2024.122542

Water research: A journal of the international water association

Water research: A journal of the international water association

EI
ISSN：0043-1354
年,卷(期)：2024.267(Dec.1)
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