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Arsenic removal from iron-containing groundwater by delayed aeration in dual-media sand filters

Journal Article (2021)
Author(s)

Md Annaduzzaman (TU Delft - Sanitary Engineering)

Luuk Rietveld (TU Delft - Sanitary Engineering)

Bilqis Amin Hoque (Environment and Population Research Center)

Md Niamul Bari (Rajshahi University of Engineering & Technology)

D. Van Halem (TU Delft - Sanitary Engineering)

Research Group
Sanitary Engineering
Copyright
© 2021 M. Annaduzzaman, L.C. Rietveld, Bilqis Amin Hoque, Md Niamul Bari, D. van Halem
DOI related publication
https://doi.org/10.1016/j.jhazmat.2020.124823
More Info
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Publication Year
2021
Language
English
Copyright
© 2021 M. Annaduzzaman, L.C. Rietveld, Bilqis Amin Hoque, Md Niamul Bari, D. van Halem
Related content
Research Group
Sanitary Engineering
Volume number
411
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Abstract

Generally, abstracted groundwater is aerated, leading to iron (Fe2+) oxidation to Fe3+ and precipitation as Fe3+-(hydr)oxide (HFO) flocs. This practice of passive groundwater treatment, however, is not considered a barrier for arsenic (As), as removal efficiencies vary widely (15–95%), depending on Fe/As ratio. This study hypothesizes that full utilization of the adsorption capacity of groundwater native-Fe2+ based HFO flocs is hampered by rapid Fe2+ oxidation-precipitation during aeration before or after storage. Therefore, delaying Fe2+ oxidation by the introduction of an anoxic storage step before aeration-filtration was investigated for As(III) oxidation and removal in Rajshahi (Bangladesh) with natural groundwater containing 329(±0.05) µgAs/L. The results indicated that As(III) oxidation in the oxic storage was higher with complete and rapid Fe2+ oxidation (2±0.01 mg/L) than in the anoxic storage system, where Fe2+ oxidation was partial (1.03±0.32 mg/L), but the oxidized As(V)/Fe removal ratio was comparatively higher for the anoxic storage system. The low pH (6.9) and dissolved oxygen (DO) concentration (0.24 mg/L) in the anoxic storage limited the rapid oxidation of Fe2+ and facilitated more As(V) removal. The groundwater native-Fe2+ (2.33±0.03 mg/L) removed 61% of As in the oxic system (storage-aeration-filtration), whereas 92% As removal was achieved in the anoxic system.