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Anoxic storage to promote arsenic removal with groundwater-native iron

Journal Article (2021)
Author(s)

Md Annaduzzaman (TU Delft - Sanitary Engineering)

Luuk C. Rietveld (TU Delft - Water Management)

D. Ghosh (Indian Institute of Science)

Bilqis Amin Amin Hoque (Environment and Population Research Centre)

D. Van Halem (TU Delft - Sanitary Engineering)

Research Group
Sanitary Engineering
Copyright
© 2021 M. Annaduzzaman, L.C. Rietveld, D. Ghosh, Bilqis A. Hoque, D. van Halem
DOI related publication
https://doi.org/10.1016/j.watres.2021.117404
More Info
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Publication Year
2021
Language
English
Copyright
© 2021 M. Annaduzzaman, L.C. Rietveld, D. Ghosh, Bilqis A. Hoque, D. van Halem
Related content
Research Group
Sanitary Engineering
Volume number
202
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Abstract

Storage containers are usually used to provide a constant water head in decentralized, community groundwater treatment systems for the removal of iron (Fe) and arsenic (As). However, the commonly practiced aeration prior to storage assists in rapid and complete Fe2+ oxidation, resulting in poor As removal, despite sufficient native-Fe2+ in the source water. In this study, it was found that application of anoxic storage enhanced As removal from groundwater, containing ≥300 µg/L of As(III) and 2.33 mg/L of Fe2+ in an As affected village of Rajshahi district in Bangladesh. Although the oxidation of Fe2+ and As(III) during oxic storage was considerably faster, the As/Fe removal ratio was higher during anoxic storage (61–80±5 µgAs/mgFe) compared to the oxic storage (45±5 µgAs/mgFe). This higher As removal efficacy in anoxic storage containers could not be attributed to the speciation of As, since As(V) concentrations were higher during oxic storage due to more favorable abiotic (As(III) oxidation by O2 and Fenton-like intermediates) and biotic (As(III) oxidizing bacteria, e.g., Sideroxydans, Gallionella, Hydrogenophaga) conditions. The continuous, in-situ hydrous ferric oxide floc formation during flow-through operation, and the favorable lower pH aiding higher sorption capacities for the gradually formed As(V) likely contributed to the improved performance in the anoxic storage containers.