Engineering and Implementation Challenges for Chlorinated Solvent Remediation

Simpkin, Thomas J.; Norris, Robert D.

doi:10.1007/978-1-4419-1401-9_5

Cited by 6 publications

(6 citation statements)

References 27 publications

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“…Additions of cofactors such as vitamin B 12 and complex nutrient supplements have been found to enhance both the dechlorination and growth of Dehalococcoides (24). Identification of other important growth factors for the robust and sustained cultivation of Dehalococcoides could lead to improved understanding of the physiology of this organism and to potentially more successful bioremediation strategies (36,41). Conventional cultivation-dependent screening techniques, such as a monofactorial analysis in batch culture experiments by stepwise omission of single amino acids, can be used for such identification as demonstrated by Holliger et al (13) in their study with Dehalobacter restrictus.…”

Section: Discussionmentioning

confidence: 99%

“…However, bioremediation applications are limited by several physiological characteristics of Dehalococcoides that make these bacteria challenging to stimulate in the environment or to cultivate in the laboratory, including long doubling times (0.8 to 2.4 days), low cell yields (0.24 to 4.9 g of protein/mol of Cl Ϫ released) (8), and specific requirements for a variety of exogenously supplied compounds (e.g., hydrogen as an electron donor, acetate as a carbon source, and cobalamin as a cofactor) (9,24,35). Further, it has been reported that generating large quantities of active Dehalococcoides in a timely manner can represent a significant challenge (36,41). Recent genome sequencing and annotation of several Dehalococcoides isolates have enabled novel molecular and biochemical approaches to improve our understanding of their physiology (16,17,20,39), which in turn can lead to the identification of biological mechanisms that limit bioremediation applications using Dehalococcoides species.…”

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confidence: 99%

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Selective Utilization of Exogenous Amino Acids by Dehalococcoides ethenogenes Strain 195 and Its Effects on Growth and Dechlorination Activity

Zhuang

Feng

et al. 2011

Appl Environ Microbiol

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Bacteria of the genus Dehalococcoides are important members of bioremediation communities because of their ability to detoxify chloroethenes to the benign end product ethene. Genome-enabled studies conducted with Dehalococcoides ethenogenes 195 have revealed that two ATP-binding cassette (ABC)-type amino acid transporters are expressed during its exponential growth stages. In light of previous findings that Casamino Acids enhanced its dechlorination activity, we hypothesized that strain 195 is capable of importing amino acids from its environment to facilitate dechlorination and growth. To test this hypothesis, we applied isotopomerbased dilution analysis with 13 C-labeled acetate to differentiate the amino acids that were taken up by strain 195 from those synthesized de novo and to determine the physiological changes caused by the significantly incorporated amino acids. Our results showed that glutamate/glutamine and aspartate/asparagine were almost exclusively synthesized by strain 195, even when provided in excess in the medium. In contrast, phenylalanine, isoleucine, leucine, and methionine were identified as the four most highly incorporated amino acids, at levels >30% of respective proteinogenic amino acids. When either phenylalanine or all four highly incorporated amino acids were added to the defined mineral medium, the growth rates, dechlorination activities, and yields of strain 195 were enhanced to levels similar to those observed with supplementation with 20 amino acids. However, genes for the putative ABC-type amino acids transporters and phenylalanine biosynthesis exhibited insignificant regulation in response to the imported amino acids. This study also demonstrates that using isotopomer-based metabolite analysis can be an efficient strategy for optimizing nutritional conditions for slow-growing microorganisms.

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Selective Utilization of Exogenous Amino Acids by Dehalococcoides ethenogenes Strain 195 and Its Effects on Growth and Dechlorination Activity

Zhuang

Feng

et al. 2011

Appl Environ Microbiol

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“…When groundwater or soil contamination occurs near buildings, volatile contaminants can migrate upward and result in vapor-phase contaminant intrusion into the indoor air, a phenomenon called vapor intrusion. Chlorinated volatile organic compounds (CVOCs) are among the most frequently detected groundwater contaminants at hazardous waste sites in the United States, persist in the environment, are difficult to remediate, and hence may pose long-term exposure risks. − …”

Section: Introductionmentioning

confidence: 99%

Screening Houses for Vapor Intrusion Risks: A Multiple Regression Analysis Approach

Johnston

Gibson

2013

Environ. Sci. Technol.

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The migration of chlorinated volatile organic compounds from groundwater to indoor air-known as vapor intrusion-can be an important exposure pathway at hazardous waste sites. Because sampling indoor air at every potentially affected home is often logistically infeasible, screening tools are needed to help identify at-risk homes. Currently, the U.S. Environmental Protection Agency (EPA) uses a simple screening approach that employs a generic vapor "attenuation factor," the ratio of the indoor air pollutant concentration to the pollutant concentration in the soil gas directly above the groundwater table. At every potentially affected home above contaminated groundwater, the EPA assumes the vapor attenuation factor is less than 1/1000--that is, that the indoor air concentration will not exceed 1/1000 times the soil-gas concentration immediately above groundwater. This paper reports on a screening-level model that improves on the EPA approach by considering environmental, contaminant, and household characteristics. The model is based on an analysis of the EPA's vapor intrusion database, which contains almost 2,400 indoor air and corresponding subsurface concentration samples collected in 15 states. We use the site data to develop a multilevel regression model for predicting the vapor attenuation factor. We find that the attenuation factor varies significantly with soil type, depth to groundwater, season, household foundation type, and contaminant molecular weight. The resulting model decreases the rate of false negatives compared to EPA's screening approach.

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“…Hydraulic fracturing can aid in overcoming geologic constraints that limit adequate in situ delivery of substrates and/or nutrients required for sustained microbial metabolism or oxidative/reductive reactions in the subsurface environment (G. Lu & Zheng, 2003). In particular, a major limitation on the effectiveness of in situ treatment processes is achieving adequate distribution of treatment amendments beyond the injection point and into the contaminated soil mass and groundwater (Nyer & Page, 2004;Simpkin & Norris, 2010). Hydraulic fracturing has been shown to effectively distribute amendment around an injection zone Sorenson et al, 2002); however, the fractures can have a random orientation and may propagate to previously installed monitoring wells that provide a pressure relief during injections (Suthersan, Horst, Nelson, & Schnobrich, 2011).…”

Section: Hydraulic Fracturing For Environmental Remediationmentioning

confidence: 99%

Remediating TCE‐contaminated groundwater in low‐permeability media using hydraulic fracturing to emplace zero‐valent iron/organic carbon amendment

Swift¹,

Rothermel²,

Peterson³

et al. 2012

Remediation Journal

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A field pilot test in which hydraulic fracturing was used to emplace granular remediation amendment (a mixture of zero‐valent iron [ZVI] and organic carbon) into fine‐grained sandstone to remediate dissolved trichloroethene (TCE)‐contaminated groundwater was performed at a former intercontinental ballistic missile site in Colorado. Hydraulic fracturing was used to enhance the permeability of the aquifer with concurrent emplacement of amendment that facilitates TCE degradation. Geophysical monitoring and inverse modeling show that the network of amendment‐filled fractures extends throughout the aquifer volume targeted in the pilot test zone. Two years of subsequent groundwater monitoring demonstrate that amendment addition resulted in development of geochemical conditions favorable to both abiotic and biological TCE degradation, that TCE concentrations were substantially reduced (i.e., greater than 90 percent reduction in TCE mass), and that the primary degradation processes are likely abiotic. The pilot‐test data aided in re‐evaluating the conceptual site model and in designing the full‐scale remedy to address a larger portion of the TCE‐contaminated groundwater plume. © 2012 Wiley Periodicals, Inc.

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Engineering and Implementation Challenges for Chlorinated Solvent Remediation

Cited by 6 publications

References 27 publications

Selective Utilization of Exogenous Amino Acids by Dehalococcoides ethenogenes Strain 195 and Its Effects on Growth and Dechlorination Activity

Selective Utilization of Exogenous Amino Acids by Dehalococcoides ethenogenes Strain 195 and Its Effects on Growth and Dechlorination Activity

Screening Houses for Vapor Intrusion Risks: A Multiple Regression Analysis Approach

Remediating TCE‐contaminated groundwater in low‐permeability media using hydraulic fracturing to emplace zero‐valent iron/organic carbon amendment

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