Biogenic Fe(III) Minerals Lower the Efficiency of Iron-Mineral-Based Commercial Filter Systems for Arsenic Removal

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• 作者：Susanne Kleinert ; Eva M. Muehe ; Nicole R. Posth ; Urs Dippon ; Birgit Daus ; Andreas Kappler
• 刊名：Environmental Science & Technology
• 出版年：2011
• 出版时间：September 1, 2011
• 年：2011
• 卷：45
• 期：17
• 页码：7533-7541
• 全文大小：972K
• 年卷期：v.45,no.17(September 1, 2011)
• ISSN：1520-5851

文摘

Millions of people worldwide are affected by As (arsenic) contaminated groundwater. Fe(III) (oxy)hydroxides sorb As efficiently and are therefore used in water purification filters. Commercial filters containing abiogenic Fe(III) (oxy)hydroxides (GEH) showed varying As removal, and it was unclear whether Fe(II)-oxidizing bacteria influenced filter efficiency. We found up to 10⁷ Fe(II)-oxidizing bacteria/g dry-weight in GEH-filters and determined the performance of filter material in the presence and absence of Fe(II)-oxidizing bacteria. GEH-material sorbed 1.7 mmol As(V)/g Fe and was 8 times more efficient than biogenic Fe(III) minerals that sorbed only 208.3 渭mol As(V)/g Fe. This was also 5 times more efficient than a 10:1-mixture of GEH-material and biogenic Fe(III) minerals that bound 322.6 渭mol As(V)/g Fe. Coprecipitation of As(V) with biogenic Fe(III) minerals removed 343.0 渭mol As(V)/g Fe, while As removal by coprecipitation with biogenic minerals in the presence of GEH-material was slightly less efficient as GEH-material only and yielded 1.5 mmol As(V)/g Fe. The present study thus suggests that the formation of biogenic Fe(III) minerals lowers rather than increases As removal efficiency of the filters probably due to the repulsion of the negatively charged arsenate by the negatively charged biogenic minerals. For this reason we recommend excluding microorganisms from filters (e.g., by activated carbon filters) to maintain their high As removal capacity.