Iron-based subsurface arsenic removal (SAR): Results of a long-term pilot-scale test in Vietnam

Edgardo E Cañas Kurz; Vu T Luong; Ulrich Hellriegel; Felix Leidinger; Tran L Luu; Jochen Bundschuh; Jan Hoinkis

doi:10.1016/j.watres.2020.115929

Iron-based subsurface arsenic removal (SAR): Results of a long-term pilot-scale test in Vietnam

Water Res. 2020 Aug 15:181:115929. doi: 10.1016/j.watres.2020.115929. Epub 2020 May 16.

Authors

Edgardo E Cañas Kurz¹, Vu T Luong², Ulrich Hellriegel¹, Felix Leidinger³, Tran L Luu⁴, Jochen Bundschuh⁵, Jan Hoinkis⁶

Affiliations

¹ Center of Applied Research, Karlsruhe University of Applied Sciences, Moltkestr. 30, 76133, Karlsruhe, Germany; Laboratory of Industrial and Synthetic Organic Chemistry (LISOC), Department of Chemistry and Chemical Technologies, University of Calabria, Via Pietro Bucci 12/C, 87036, Arcavacata di Rende, CS, Italy; Institute on Membrane Technology, National Research Council (ITM-CNR), Via Pietro Bucci 17/C, 87036, Arcavacata di Rende, CS, Italy.
² Department of Mechatronics and Sensor Systems Technology, Vietnamese-German University, Le Lai Street, 822096, Binh Duong Province, Viet Nam; Department of Separation Science, School of Engineering Science, Lappeenranta-Lahti University of Technology, Sammonkatu 12, 50130, Mikkeli, Finland.
³ Center of Applied Research, Karlsruhe University of Applied Sciences, Moltkestr. 30, 76133, Karlsruhe, Germany.
⁴ Department of Mechatronics and Sensor Systems Technology, Vietnamese-German University, Le Lai Street, 822096, Binh Duong Province, Viet Nam.
⁵ School of Civil Engineering and Surveying, University of Southern Queensland, West Street, Toowoomba, 4350, Queensland, Australia; UNESCO Chair on Groundwater Arsenic within the 2030 Agenda for Sustainable Development, University of Southern Queensland, West Street, Toowoomba, 4350, Queensland, Australia.
⁶ Center of Applied Research, Karlsruhe University of Applied Sciences, Moltkestr. 30, 76133, Karlsruhe, Germany; School of Civil Engineering and Surveying, University of Southern Queensland, West Street, Toowoomba, 4350, Queensland, Australia. Electronic address: jan.hoinkis@hs-karlsruhe.de.

PMID: 32505884
DOI: 10.1016/j.watres.2020.115929

Abstract

The principle of subsurface arsenic removal (SAR) from groundwater is based on oxidation and adsorption reactions by infiltrating oxygen into the anoxic aquifer and the immobilization of arsenic (As) onto freshly formed iron (Fe)-(hydr)oxides. In this study, a pilot-scale plant for SAR has been subject to long term testing in the Mekong Delta, Vietnam. Initial concentrations of Fe (8.4 ± 1.3 mg L^-1) and As (81 ± 8 μg L^-1) in the exploited groundwater were successfully lowered to below the WHO guideline value limits for drinking water of 0.3 mg L^-1 and 10 μg L^-1, respectively. Adsorption and co-precipitation of As with Fe-(hydr)oxides could be identified as the principal mechanism responsible for the As removal from groundwater, demonstrating the feasibility of SAR as a low-cost and zero-waste solution over a period of two years. However, naturally occurring geochemical reducing conditions and high ammonium levels in the groundwater delayed the removal of manganese (Mn). An additional post-treatment filtration for Mn-removal was temporarily used to comply with the Vietnamese drinking water standard until a Mn-mitigation was achieved by the SAR process. In contrast to most As-remediation technologies, SAR appears to be a long-term, sustainable treatment option with the salient advantage of negligible production of toxic waste, which with ex-situ processes require additionally management costs.

Keywords: Groundwater contamination; Low-cost; Mekong delta; Oxidation/adsorption; Subsurface arsenic mitigation; Zero-waste.

MeSH terms

Arsenic*
Groundwater*
Iron
Vietnam
Water Pollutants, Chemical*
Water Purification*

Substances

Water Pollutants, Chemical
Iron
Arsenic