The results of a field experiment designed to test the effectiveness of a novel approach for long-term, in situ bioimmobilization of toxic and soluble Cr(VI) in groundwater using a hydrogen release compound (HRC)--a slow release glycerol polylactate--are described. The field experiment was conducted at the Hanford Site (Washington), a U.S. Department of Energy nuclear production facility, using a combination of hydrogeological, geophysical, geochemical, and microbiological measurements and analyses of water samples and sediments. The results of this experiment show that a single HRC injection into groundwater stimulates an increase in biomass, a depletion of terminal electron acceptors O2, NO3-, and SO4(2-), and an increase in Fe2+, resulting in a significant decrease in soluble Cr(VI). The Cr(VI) concentration has remained below the background concentration in the downgradient pumping/ monitoring well, and below the detection limit in the injection well for more than 3 years after the HRC injection. The degree of sustainability of Cr(VI) reductive bioimmobilization under different redox conditions at this and other contaminated sites is currently under study.
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http://dx.doi.org/10.1021/es801383r | DOI Listing |
Water Res
September 2024
School of Environment and Resources, Taiyuan University of Science and Technology, Taiyuan 030024, China.
Microbes possessing electron transfer capabilities hold great promise for remediating subsurface contaminated by redox-active radionuclides such as technetium-99 (TcO) through bio-transformation of soluble contaminants into their sparingly soluble forms. However, the practical application of this concept has been impeded due to the low electron transfer efficiency and long-term product stability under various biogeochemical conditions. Herein, we proposed and tested a pyrite-stimulated bio-immobilization strategy for immobilizing ReO (a nonradioactive analogue of TcO) using sulfate-reducing bacteria (SRB), with a focus on pure-cultured Desulfovibrio vulgaris.
View Article and Find Full Text PDFEnviron Sci Technol
December 2019
Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing 100085 , P. R. China.
Removal of uranium from groundwater is of great significance as compared to in situ bioimmobilization technology. In this study, a novel direct electro-reductive method has been developed to efficiently remove and recover uranium from carbonate-containing groundwater, where U(VI)O(CO) and CaU(VI)O(CO) are the dominant U species. The transferred electron calculations and XPS, XRD analyses confirmed that U(VI) was reduced to U(IV)O and accumulated on the surface of the Ti electrode (defined as Ti@U(IV)O electrode) with high current efficiencies (over 90.
View Article and Find Full Text PDFChemosphere
October 2011
Ecology Department, Earth Sciences Division, Lawrence Berkeley National Laboratory, CA 94720, United States.
To evaluate the efficacy of bioimmobilization of Cr(VI) in groundwater at the Department of Energy Hanford site, we conducted a series of microcosm experiments using a range of commercial electron donors with varying degrees of lactate polymerization (polylactate). These experiments were conducted using Hanford Formation sediments (coarse sand and gravel) immersed in Hanford groundwater, which were amended with Cr(VI) and several types of lactate-based electron donors (Hydrogen Release Compound, HRC; primer-HRC, pHRC; extended release HRC) and the polylactate-cysteine form (Metal Remediation Compound, MRC). The results showed that polylactate compounds stimulated an increase in bacterial biomass and activity to a greater extent than sodium lactate when applied at equivalent carbon concentrations.
View Article and Find Full Text PDFJ Contam Hydrol
March 2010
Department of Civil Engineering, Oregon State University, USA.
'Bioimmobilization' of redox-sensitive heavy metals and radionuclides is being investigated as a way to remediate contaminated groundwater and sediments. In one approach, growth-limiting substrates are added to the subsurface to stimulate the activity of targeted groups of indigenous microorganisms and create conditions favorable for the microbially-mediated reductive precipitation ('bioreduction') of targeted contaminants. We present a theoretical framework for modeling this process that modifies conventional geochemical reaction path modeling to include thermodynamic descriptions for microbial growth and may be called biogeochemical reaction path modeling.
View Article and Find Full Text PDFEnviron Sci Technol
November 2008
Lawrence Berkeley National Laboratory, Berkeley, California, USA.
The results of a field experiment designed to test the effectiveness of a novel approach for long-term, in situ bioimmobilization of toxic and soluble Cr(VI) in groundwater using a hydrogen release compound (HRC)--a slow release glycerol polylactate--are described. The field experiment was conducted at the Hanford Site (Washington), a U.S.
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