Anoxic storage to promote arsenic removal with groundwater-native iron

WATER RESEARCH

卷:202

Article

Annaduzzaman, Md¹  Rietveld, Luuk C.¹  Ghosh, Devanita²  Hoque, Bilqis A.³  van Halem, Doris¹ 

[1] Delft Univ Technol, Water Management Dept, Sanit Engn Sect, Delft, Netherlands

[2] Indian Inst Sci, Ctr Earth Sci, Lab Biogeochem Mystery, Bangalore, Karnataka, India

[3] Environm & Populat Res Ctr, Dhaka, Bangladesh

关键词: Groundwater;    Treatment;    Anoxic;    Storage container;    Arsenic;    Iron;   

DOI  :  10.1016/j.watres.2021.117404

来源: Elsevier

【 摘 要 】

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 nativeFe(2+) in the source water. In this study, it was found that application of anoxic storage enhanced As removal from groundwater, containing >= 300 mu g/L of As(III) and 2.33 mg/L of Fe(2+ )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 mu gAs/mgFe) compared to the oxic storage (45 +/- 5 mu gAs/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 O-2 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 flowthrough 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.

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