In Situ Treatment of Chlorinated Ethene-Contaminated Groundwater Using Horizontal Flow Treatment Wells PDF Download

Author: Derek R. Ferland
Publisher:
ISBN: 9781423539056
Category : Groundwater
Languages : en
Pages : 94

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Book Description
The limitations of conventional containment technologies for groundwater contaminated with chlorinated solvents have motivated development of innovative technologies to achieve national groundwater remediation objectives. One inn9vative technology that is currently under development involves metal reductants or catalysts to chemically destroy the dissolved chlorinated solvent. Models are important tools that can be used to help transition this technology to the field. Model studies can be used to gain understanding about the technology, help determine when the prospective technology might work for a given site, and design full-scale field applications.

Author: Michael L. Shelley
Publisher:
ISBN: 9781423549208
Category :
Languages : en
Pages : 68

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Book Description
This work explores two innovative technologies for the remediation of chlorinated ethene solvents contaminating groundwater: (1) groundwater circulation wells (GCWs) with downwell zero-valent metal reductive dechlorination reactors, and (2) constructed vertical subsurface flow wetlands. Both the natural dechlorination in wetland sediments, and the engineered dechlorination in a well using zero-valent metals have major implications for the treatment of Air Force pollutants, with the potential to save millions of dollars annually in long term remediation at hundreds of sites across the Air Force. Complementary modeling and column studies examined the potential for controlling and treating groundwater contamination using groundwater circulation wells (GCWs) with downwell zero-valent metal reductive dechlorination reactors. The construction of the field scale wetland research facility includes two complete wetland cells (140 x 60 feet each), fully contained. Chemical analysis of samples drawn from the various depths of wetland sediment suggests a very heterogeneous development of microbial activity relevant to reductive dechlorination over the course of one year of operation. Concentration contours of PCE, TCE, and nitrate suggest that reductive dechlorination is taking place when more readily reducible electron acceptors (like nitrate) are depleted. PCE is reduced ten-fold from inflow to outflow, even with significant short- circuiting of flow from the bottom sediments to the outflow. Data suggests 100- fold treatment is possible.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 68

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Book Description
This work explores two innovative technologies for the remediation of chlorinated ethene solvents contaminating groundwater: (1) groundwater circulation wells (GCWs) with downwell zero-valent metal reductive dechlorination reactors, and (2) constructed vertical subsurface flow wetlands. Both the natural dechlorination in wetland sediments, and the engineered dechlorination in a well using zero-valent metals have major implications for the treatment of Air Force pollutants, with the potential to save millions of dollars annually in long term remediation at hundreds of sites across the Air Force. Complementary modeling and column studies examined the potential for controlling and treating groundwater contamination using groundwater circulation wells (GCWs) with downwell zero-valent metal reductive dechlorination reactors. The construction of the field scale wetland research facility includes two complete wetland cells (140 x 60 feet each), fully contained. Chemical analysis of samples drawn from the various depths of wetland sediment suggests a very heterogeneous development of microbial activity relevant to reductive dechlorination over the course of one year of operation. Concentration contours of PCE, TCE, and nitrate suggest that reductive dechlorination is taking place when more readily reducible electron acceptors (like nitrate) are depleted. PCE is reduced ten-fold from inflow to outflow, even with significant short-circuiting of flow from the bottom sediments to the outflow. Data suggests 100-fold treatment is possible.

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 270

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Book Description
The U.S. Environmental Protection Agency (EPA) estimated in 1996 that approximately 70% of the 8,336 Department of Defense (DoD) sites requiring cleanup had contaminated groundwater, usually from chlorinated solvents such as trichloroethylene (TCE) and tetrachloroethylene (PCE). Palladium (Pd) catalysis is a rapid destruction method that, in the presence of hydrogen gas, transforms many chlorinated ethylenes into ethane and some other halogenated volatile organic compounds (VOCs) into their respective hydrocarbon compounds. The dechlorination reactions for chlorinated ethylenes are complete and rapid and occur in water under ambient temperature, pH and pressure conditions. Hydrogen gas is used as the reducing agent, with residence times on the order of minutes. Catalytic contaminant destruction in a one-pass process has many potential advantages such as eliminating the secondary waste stream created by other processes that transfer contaminants to another medium (e.g. air or activated carbon). The technology is also effective in areas of high contaminant concentrations making it applicable to source control. The objective of this project was to demonstrate the feasibility of catalytic destruction of chlorinated VOCs in groundwater using reactors containing palladium-coated beads that were operated in-situ within two previously established horizontal flow treatment wells (HFTWs). Although installation of the reactors inside the treatment wells could be possible in a full scale application, it is not recommended due to complications associated with installing feed lines for backflushing and regenerating reactors coupled with high costs for removing reactors from the wells for maintenance, leak checks, etc.

Author: Hans F. Stroo
Publisher: Springer Science & Business Media
ISBN: 1441914013
Category : Technology & Engineering
Languages : en
Pages : 807

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Book Description
In the late 1970s and early 1980s, our nation began to grapple with the legacy of past disposal practices for toxic chemicals. With the passage in 1980 of the Comprehensive Envir- mental Response, Compensation, and Liability Act (CERCLA), commonly known as Sup- fund, it became the law of the land to remediate these sites. The U. S. Department of Defense (DoD), the nation’s largest industrial organization, also recognized that it too had a legacy of contaminated sites. Historic operations at Army, Navy, Air Force, and Marine Corps facilities, ranges, manufacturing sites, shipyards, and depots had resulted in widespread contamination of soil, groundwater, and sediment. While Superfund began in 1980 to focus on remediation of heavily contaminated sites largely abandoned or neglected by the private sector, the DoD had already initiated its Installation Restoration Program in the mid-1970s. In 1984, the DoD began the Defense Environmental Restoration Program (DERP) for contaminated site assessment and remediation. Two years later, the U. S. Congress codified the DERP and directed the Secretary of Defense to carry out a concurrent program of research, development, and demonstration of innovative remediation technologies. As chronicled in the 1994 National Research Council report, “Ranking Hazardous-Waste Sites for Remedial Action,” our early estimates on the cost and suitability of existing techn- ogies for cleaning up contaminated sites were wildly optimistic. Original estimates, in 1980, projected an average Superfund cleanup cost of a mere $3.

Author: James M. Waldron
Publisher:
ISBN:
Category : Groundwater
Languages : en
Pages : 242

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Book Description

Author: Michael R. Staples
Publisher:
ISBN: 9781423511700
Category : Chlorohydrocarbons
Languages : en
Pages : 108

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Book Description
Past research has shown that there is a rising public concern with environmental issues in the Republic of Korea (ROK). As Korean government and public interest in the environment grow, there is likely to be increased pressure to remediate environmental contamination at United States Department of Defense (DoD) installations in Korea. Impacting DoD's ability to remediate contaminated sites overseas is the fact that limited environmental funds must compete with high priority mission requirements. Thus, particularly at overseas bases, there is an urgent need for inexpensive and effective groundwater remediation technologies. Horizontal Flow Treatment Well (HFTW) systems have been demonstrated in the U.S. to be an effective technology for managing groundwater contamination. However, the problem of finding a technology that is appropriate for use in Korea is particularly challenging due to the fractured aquifer systems that are ubiquitous throughout the Korean peninsula. The model analyses conducted in this study found that HFTWs have the potential to be a cost effective alternative to conventional technologies for contaminant management in the fractured media found in Korea. This study focused on the containment of groundwater contaminated with chlorinated solvents in the fractured rock aquifers that are commonly encountered at DoD installations in the ROK. Horizontal Flow Treatment Wells were analyzed as a potentially cheaper, safer, and more effective technology for the containment of chlorinated solvent contaminated groundwater. In this study, an HFTW numerical model that was developed for porous media was applied to the fractured systems encountered in the ROK. It was concluded that at the scale of interest, use of a porous media model was appropriate. Both hydrogeologic and design parameters were varied to determine their effects on the technology performance.

Author: Jeffrey C. Parr
Publisher:
ISBN: 9781423511878
Category : Groundwater
Languages : en
Pages : 155

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Book Description
Groundwater contamination by perchlorate has recently been recognized as a significant environmental problem across the United States, and especially at Department of Defense facilities. In this study, a model is used to evaluate the potential of a innovative in situ bioremediation technology using Horizontal Flow Treatment Wells (HFTWs) to manage perchlorate-contaminated groundwater. The technology uses HFTWs to mix an electron donor into perchlorate-contaminated groundwater in order to promote reduction of the perchlorate by indigenous microorganisms in bioactive zones within the aquifer, as well as recirculate the contaminated water between treatment well pairs to achieve multiple passes of contaminated water through the bioactive zones. The model used in this study couples a three-dimensional fate and transport model, which simulates advective/ dispersive transport of solutes induced by regional groundwater flow and operation of the HFTW's, with a biodegradation model that simulates perchlorate reduction, as well as reduction of competing electron acceptors in the groundwater, by indigenous microorganisms. The model was applied to an example site to demonstrate how in situ perchlorate treatment might be implemented. A sensitivity analysis using the model is also conducted to evaluate which engineered and environmental parameters most affect technology performance. Model simulation results demonstrate that this technology may be effective in managing perchlorate-contaminated groundwater. The recirculation induced by the HFTW system results in increased treatment efficiency, as compared to treatment that would be achieved by a single pass of contaminated water through the bioactive zones. It was observed that the model was very sensitive to several kinetic parameters, indicating that a fruitful area for future research would be to study how these important parameters can be accurately quantified for given geochemical and microbiological conditions.

Author:
Publisher:
ISBN:
Category : Chlorohydrocarbons
Languages : en
Pages : 90

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Book Description

Author: Preston F. Rufe
Publisher:
ISBN: 9781423518570
Category : Butyl methyl ether
Languages : en
Pages : 227

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Book Description
This study utilized a three-dimensional numerical model to evaluate the potential application of HFTWs to manage MTBE-contaminated groundwater. HFTWs consist of two dual-screened treatment wells. One well operates in an upflow mode, with MTBE-contaminated water extracted from an aquifer through a screen in the deep portion of an aquifer and injected into the aquifer through a shallow well screen, while the adjacent well operates in a downflow mode, extracting water from the shallow zone of the aquifer and injecting it into the deep zone. As the MTBE-contaminated water flows through the wells, an electron acceptor and/or another electron donor is introduced in order to promote oxidation of MTBE by indigenous microorganisms that grow in bioactive zones adjacent to the injection screens of the treatment wells. The model used in this study couples a model that simulates the complex three-dimensional flow field that results from HFTW operation with a transport model to simulate MTBE fate due to advective/dispersive transport and biodegradation. The biodegradation model allows simulation of either direct or cometabolic oxidation of MTBE by indigenous microorganisms. The model was applied to a hypothetical MTBE- contaminated site to demonstrate how this technology might effect in situ MTBE treatment. A sensitivity analysis was conducted using the model to determine the engineering and environmental parameters that impact technology performance. This study demonstrates that the HFTW technology has potential for application in managing MTBE-contaminated groundwater.