Bacterially Induced Calcium Carbonate Precipitation and Strontium Coprecipitation in a Porous Media Flow System

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• 作者：Ellen G. Lauchnor ; Logan N. Schultz ; Steven Bugni ; Andrew C. Mitchell ; Alfred B. Cunningham ; Robin Gerlach
• 刊名：Environmental Science & Technology (ES&T)
• 出版年：2013
• 出版时间：February 5, 2013
• 年：2013
• 卷：47
• 期：3
• 页码：1557-1564
• 全文大小：421K
• 年卷期：v.47,no.3(February 5, 2013)
• ISSN：1520-5851

文摘

Strontium-90 is a principal radionuclide contaminant in the subsurface at several Department of Energy sites in the Western U.S., causing a threat to groundwater quality in areas such as Hanford, WA. In this work, we used laboratory-scale porous media flow cells to examine a potential remediation strategy employing coprecipitation of strontium in carbonate minerals. CaCOb>3b> precipitation and strontium coprecipitation were induced via ureolysis by Sporosarcina pasteurii in two-dimensional porous media reactors. An injection strategy using pulsed injection of calcium mineralization medium was tested against a continuous injection strategy. The pulsed injection strategy involved periods of lowered calcite saturation index combined with short high fluid velocity flow periods of calcium mineralization medium followed by stagnation (no-flow) periods to promote homogeneous CaCOb>3b> precipitation. By alternating the addition of mineralization and growth media the pulsed strategy promoted CaCOb>3b> precipitation while sustaining the ureolytic culture over time. Both injection strategies achieved ureolysis with subsequent CaCOb>3b> precipitation and strontium coprecipitation. The pulsed injection strategy precipitated 71鈥?5% of calcium and 59% of strontium, while the continuous injection was less efficient and precipitated 61% of calcium and 56% of strontium. Over the 60 day operation of the pulsed reactors, ureolysis was continually observed, suggesting that the balance between growth and precipitation phases allowed for continued cell viability. Our results support the pulsed injection strategy as a viable option for ureolysis-induced strontium coprecipitation because it may reduce the likelihood of injection well accumulation caused by localized mineral plugging while Sr coprecipitation efficiency is maintained in field-scale applications.