Bioremediation of strontium and technetium contaminated groundwater using glycerol phosphate
Bioremediation of strontium and technetium contaminated groundwater using glycerol phosphate
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DOI：
10.1016/j.chemgeo.2019.02.004
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发表时间：
2019-03-30
期刊：
影响因子：
3.9
通讯作者：
Morris, K.
中科院分区：
文献类型：
--
作者：
Cleary, A.;Lloyd, J. R.;Morris, K.
世界各地遗留核设施的地下水受到放射性核素的污染，包括锶-90和锝-99，它们通常作为共同污染物存在。在这里，我们调查了是否可以通过掺入磷酸盐生物矿物的生物刺激土著微生物群落的Sr-90，和Tc-99通过微生物诱导的沉积物的还原，以形成较少的移动的Tc（IV）相通过与还原物种（如Fe（II））的反应。结果表明，95%的Sr被从溶液中去除，在用磷酸甘油处理的沉积物微宇宙，和连续提取表明，类似于18%的Sr在所得的固相与pH 5的乙酸钠馏分和75%的离子可交换馏分。这种去除和分配的柠檬酸相在甘油磷酸盐处理过程中是大于在未经处理的控制，其中只有60%的Sr从溶液中除去，和固体相关的Sr，95%是存在于可交换的部分。锶K-边EXAFS光谱拟合证实了这些发现，与壳的壳拟合建议类似的30%的沉积物相关的Sr是存在于一个协调的环境中与磷酸盐生物矿物甘油磷酸盐处理后，而Sr只作为外层复合物的控制。此外，用磷酸甘油刺激的沉积物的16 S rRNA测序证明了潜在的磷酸盐溶解物种如金黄杆菌和沙雷氏菌属的生长。最后，甘油磷酸盐处理刺激生物还原，通过添加电子供体的形式，甘油的系统，反过来，这刺激去除Tc-99从溶液中伴随着微生物的Fe（III）还原，形成难溶性水合Tc（IV）O-2样相。在沉积物中修订的电子供体，微生物群落也反映了生物还原的发病与Fe（III）和硫酸盐还原菌，如Geothrbc，Geophyll和Desulfobulbus属的相对丰度增加。总的来说，这些结果表明，甘油磷酸盐的应用提供了一个有前途的生物修复策略，共同处理Sr-90和Tc-99污染的地下水，并促进Sr-磷酸盐和Tc（IV）轴承生物矿物的形成时，保持还原条件。结合过去的工作，显示清除铀从溶液中加入甘油磷酸盐，这扩大了甘油磷酸盐作为地下水放射性污染的治疗范围。
Groundwater at legacy nuclear facilities around the world is contaminated with radionuclides including strontium-90 and technetium-99, which are often present as co-contaminants. Here we investigated whether biostimulation of indigenous microbial communities by glycerol phosphate can co-treat Sr-90 through incorporation into phosphate biominerals, and Tc-99 through microbially-induced reduction of the sediment to form less mobile Tc(IV) phases via reaction with reduced species (e.g. Fe(II)). Results showed that 95% of Sr was removed from solution in sediment microcosms treated with glycerol phosphate, and sequential extraction showed that similar to 18% of the Sr in the resulting solid phase was associated with the pH 5 Na-acetate fraction and 75% was in the ion exchangeable fraction. This removal and partitioning to recalcitrant phases during glycerol phosphate treatment was greater than in the untreated controls, where only 60% of Sr was removed from solution, and of the solid-associated Sr, 95% was present in the exchangeable fraction. Fitting of Sr K-edge EXAFS spectra confirmed these findings, with shell by shell fitting suggesting similar to 30% of sediment-associated Sr was present in a coordination environment consistent with phosphate biominerals following glycerol phosphate treatment, whilst Sr was present only as outer-sphere complexes in the controls. In addition,16S rRNA sequencing of sediments stimulated with glycerol phosphate demonstrated the growth of potential phosphate-solubilising species such as Chryseobacterium and Serratia spp. Finally, glycerol phosphate treatment stimulated bioreduction via addition of electron donor in the form of glycerol to the system, in turn this stimulated the removal of Tc-99 from solution concomitant with microbial Fe(III) reduction to form poorly soluble hydrous Tc (IV)O-2 like phases. In sediments amended with an electron donor, the microbial community also reflected the onset of bioreduction with an increased relative abundance of Fe(III) and sulfate-reducing bacteria such as Geothrbc, Geobacter and Desulfobulbus spp. Overall these results suggest application of glycerol phosphate offers a promising bioremediation strategy to co-treat both Sr-90 and Tc-99 contaminated groundwaters, and promotes the formation of Sr-phosphate and Tc(IV) bearing biominerals when reducing conditions are maintained. Combined with past work which shows the scavenging of uranium from solution following addition of glycerol phosphate, this extends the scope for glycerol phosphate as a treatment for radioactive contamination in groundwaters.