Geomicrobiology, Center for Applied Geosciences, University of Tuebingen, Sigwartstrasse 10, D-72076 Tuebingen, Germany.
Environ Sci Technol. 2011 Sep 1;45(17):7533-41. doi: 10.1021/es201522n. Epub 2011 Aug 1.
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 10(7) 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 μmol 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 μmol As(V)/g Fe. Coprecipitation of As(V) with biogenic Fe(III) minerals removed 343.0 μmol 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.
全世界有数百万人受到受砷污染地下水的影响。三价铁（oxy）氢氧化物有效地吸附砷，因此被用于水净化过滤器中。含有非生物成因三价铁（oxy）氢氧化物（GEH）的商业过滤器对砷的去除效果各不相同，而且不清楚是否有亚铁氧化菌会影响过滤器的效率。我们在 GEH 过滤器中发现高达 10(7) 个亚铁氧化菌/g 干重，并确定了在有亚铁氧化菌和无亚铁氧化菌存在的情况下过滤材料的性能。GEH 材料吸附 1.7mmol As(V)/gFe，比仅吸附 208.3μmol As(V)/gFe 的生物成因三价铁矿物的效率高约 8 倍。这也比 GEH 材料与生物成因三价铁矿物的 10:1 混合物的效率高约 5 倍，后者结合了 322.6μmol As(V)/gFe。砷(V)与生物成因三价铁矿物的共沉淀去除了 343.0μmol As(V)/gFe，而在 GEH 材料存在的情况下，砷(V)与生物成因矿物共沉淀的去除效率略低，GEH 材料仅去除了 1.5mmol As(V)/gFe。因此，本研究表明，生物成因三价铁矿物的形成降低了过滤器的砷去除效率，而不是提高了其效率，这可能是由于带负电荷的砷酸盐被带负电荷的生物成因矿物排斥所致。出于这个原因，我们建议从过滤器中排除微生物（例如通过活性炭过滤器），以保持其高砷去除能力。
