Uranium immobilization by sulfate-reducing biofilms
Uranium immobilization by sulfate-reducing biofilms
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DOI：
10.1021/es0348703
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发表时间：
2004-04-01
影响因子：
11.4
通讯作者：
Lewandowski, Z
中科院分区：
文献类型：
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作者：
Beyenal, H;Sani, RK;Lewandowski, Z
用硫酸盐还原细菌(SRB)脱硫弧菌G20的生物膜固定化六价铀[U(VI)]。生物膜生长在平板连续流反应器中，以乳酸为电子供体，硫酸盐为电子受体。将铀(VI)以126微米的浓度连续投加到反应器中32周。在此期间，可溶性铀(VI)被从溶液中去除(占料液的88%~96%)，并固定在生物膜中。硫酸盐还原生物膜中U的固定化动力学通过估计：(1)SRB生物膜中的微生物活性，定义为硫化氢(H_2S)的产生速率，并根据生物膜上使用微电极测量的H_2S浓度分布估计；(2)溶液中溶解U的浓度；以及(3)生物膜中U的沉淀量。结果表明，U被固定在生物膜中是两个过程的结果：(1)酶法和(2)化学方法，通过与微生物产生的硫化氢反应-目测显示，溶解的硫化物物种与U(VI)反应生成黑色沉淀物。同步加速器U L三边X射线吸收近边结构(XANES)对硫化钠非化学沉淀U的分析表明，U(VI)被还原为U(IV)。选区电子衍射图和透射电子显微镜晶格条纹图的结晶学分析证实了析出的铀为铀矿结构。
Hexavalent uranium [U(VI)] was immobilized using biofilms of the sulfate-reducing bacterium (SRB) Desulfovibrio desulfuricans G20. The biofilms were grown in flat-plate continuous-flow reactors using lactate as the electron donor and sulfate as the electron acceptor. U(VI) was continuously fed into the reactor for 32 weeks at a concentration of 126 muM. During this time, the soluble U(VI) was removed (between 88 and 96% of feed) from solution and immobilized in the biofilms. The dynamics of U immobilization in the sulfate-reducing biofilms were quantified by estimating: (1) microbial activity in the SRB biofilm, defined as the hydrogen sulfide (H2S) production rate and estimated from the H2S concentration profiles measured using microelectrodes across the biofilms; (2) concentration of dissolved U in the solution; and (3) the mass of U precipitated in the biofilm. Results suggest that U was immobilized in the biofilms as a result of two processes: (1) enzymatically and (2) chemically, by reacting with microbially generated H2S- Visual inspection showed that the dissolved sulfide species reacted with U(VI) to produce a black precipitate. Synchrotron-based U L-3-edge X-ray absorption near edge structure (XANES) spectroscopy analysis of U precipitated abiotically by sodium sulfide indicated that U(VI) had been reduced to U(IV). Selected-area electron diffraction pattern and crystallographic analysis of transmission electron microscope lattice-fringe images confirmed the structure of precipitated U as being that of uraninite.