Download or read book Characterization of Chlorinated Solvent Degradation in a Constructed Wetland written by Nathan D. Clemmer and published by . This book was released on 2003-03 with total page 159 pages. Available in PDF, EPUB and Kindle. Book excerpt: Widespread chlorinated ethene contamination of aquifers coupled with high costs of current treatment technologies demand innovative remediation solutions. Wetlands, maintaining anaerobic and aerobic zones promoting the complete degradation of chlorinated ethenes such as Tetrachloroethylene (PCE), could be the answer. This thesis characterized the chlorinated solvent contamination levels in three strata of an upward flow constructed wetland. Analysis of samples was accomplished by purge-and-trap gas chromatography. Water quality parameters, Dissolved Oxygen (DO), Oxidation Reduction Potential (ORP), pH, Conductivity, and Temperature, were also measured in monitoring wells with a water monitoring sonde. After removing data outliers caused by short-circuiting flow, PCE concentrations declined from an average of 32,59 +/- 0,699 ppb (+/- 95% confidence interval) in the inflow stream to an average of 0.171 +/- 0.079 ppb in the upper layer (99,3% reduction). Concentration trends of PCE degradation products cis-1,1 -Dichloroethylene (cis-DCE), Vinyl Chloride (VC), and Trichloroethylene TCE) indicate dechlorination processes are occurring. In addition to PCE, TCE at concentrations below 0,6 ppb was the only other analyte detected in the inflow and outflow, Water quality measurements (DO and 0RP) decreased from the bottom to the middle layer to a level that supports anaerobic reductive dechlorination but not methanogenesis. The DO increased slightly from the middle to the top layer while 0RP continued to decrease.

Download or read book Characterization of Chlorinated Solvent Degradation Profile Due to Microbial and Chemical Processes in a Constructed Wetland written by Teresa A. Sobolewski and published by . This book was released on 2004-03 with total page 97 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perchloroethene (PCE) and its degradation products are among the most common organic groundwater contaminants in the United States. Constructed wetlands are a relatively new approach to dealing with this contamination problem. With their upward flow capability it is possible to introduce an aerobic and anaerobic environment with a consortium of microorganisms available to degrade the contaminants to within acceptable levels established by the Environmental Protection Agency (EPA). This study is a follow-up to the previous two years of research on PCE degradation in cell 1 at Wright-Patterson Air Force Base. This thesis was conducted in order to study the wetland and determine the mechanisms that exist to degrade the chlorinated solvent contamination that is present. It also provided additional evidence that the constructed wetland is degrading PCE to its innocuous byproducts. A purge-and-trap gas chromatograph was used to determine the concentrations of PCE, TCE, DCE isomers, and VC throughout the three layers of the constructed wetland. Inflow and outflow were also sampled and analyzed. In this year's data, PCE was detected at a level that was below the maximum contaminant level established by the EPA. However, it is clear that Cell 1 is still developing. This wetland cell has been in existence for three years and it is obvious that the development of a constructed wetland is a lengthy process. If a constructed wetland were to be used as a treatment process for contaminated water sources, time would have to be allowed for it to develop before it would reach maximum treatment efficiency.

Download or read book Characterization of Chlorinated Ethene Degradation in a Vertical Flow Constructed Wetland written by James M. Waldron and published by . This book was released on 2007 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization of Microbial Processes that Degrade Chlorinated Solvents in a Constructed Wetland Using Organic Acid and Inorganic Anion Concentration Profiles written by and published by . This book was released on 2004-03 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chlorinated solvents have been used in industrial cleaning and degreasing processes in the United States since the early 1900s, and their induction into the environment increased significantly with the growth of industrial processes over the past century. PCE, TCE and their daughter products have been associated with a number of human health concerns and are currently the most common contaminants found in groundwater in the United States. Wetlands possess characteristics necessary for the complete degradation of chlorinated ethenes by microorganisms via anaerobic and aerobic regions that foster the necessary oxidation-reduction conditions. Organic acid and inorganic anion concentrations were evaluated in samples taken from a constructed wetland at Wright-Patterson Air Force Base, Ohio during the summer and fall of 2003. These analyses are indicative of redox conditions in the subsurface and suggest the occurrence of microbial activities that degrade chlorinated ethenes to innocuous end products. Organic acid concentrations decreased by 100% from July 2003 to fall 2003. Combined with data collected previously during the months of December and January, this suggested that changing seasons and temperature fluctuations have a significant influence on microbial metabolisms. Nitrate and sulfate reduction above stratum C indicated mildly reducing conditions in the lowest stratum that became more highly reducing in the upper two strata. Based on the changing analyst concentrations throughout the wetland cell over several seasons, it was evident that the appropriate subsurface conditions existed for the reductive dechlorination of chlorinated ethenes.

Download or read book Characterization of Microbial Processes that Degrade Chlorinated Solvents in a Constructed Wetland Using Organic Acid and Inorganic Anion Concentration Profiles written by Chad B. BonDurant and published by . This book was released on 2004 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Determination of Chlorinated Solvent Contamination in an Upward Flow Constructed Wetland written by Bryan C. Opperman and published by . This book was released on 2002-03-01 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study is to determine chlorinated solvent contamination levels in an upward flow constructed wetland at Wright-Patterson Air Force Base (WPAFB), Ohio. A stratified grid sampling methodology will be used in sampling the contaminated groundwater. Analysis will be accomplished by means of purge-and-trap gas chromatography. The contaminant concentration levels will be used to enhance the design and construction of man-made wetlands used to remove chlorinated solvents from aquifers. PCE levels declined from an average of 33.97 ppb in the inflow stream to an average of 3.65 ppb in the upper layer, a 91% reduction. High concentrations occurred in areas where high hydraulic pressure gradients and hydraulic conductivities combined to allow contaminated water to migrate to the upper layers of the wetland with minimal contact time for reduction. Removing these areas from the data set increased the PCE reduction efficiency to nearly 98% with an upper level concentration average of 0.84 ppb. Trichloroethene (TCE) inflow rates averaged 0.63 ppb while TCE concentrations in the upper layer averaged 0.175 ppb. TCE concentrations peaked in the middle layer of the wetland suggesting that reduction of PCE was occurring there and in the bottom layer.

Download or read book Analysis of Anion Distributions in the Developing Strata of a Constructed Wetland Used for Chlorinated Ethene Remediation written by Joshua D. Kovacic and published by . This book was released on 2003-03 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: Perchloroethene (PCE), Trichloroethene (TCE) and their degradation products are among the most common organic groundwater contaminants in the United States. Constructed wetlands utilizing upward flow harbor reduction- oxidation conditions that have demonstrated the potential to promote both partial and total mineralization of PCE and TCE through the process of natural attenuation. Organic acid and inorganic anion concentrations are indicative of reduction-oxidation processes that drive chlorinated ethene degradation. These analytes were investigated to assess their development within three vertically stratified regions of a constructed wetland cell at Wright-Patterson Air Force Base fed by groundwater contaminated with PCE and TCE. Data collected during the months of January 2002, December 2002, and January 2003 revealed changes in the organic acid pool over time and in space that correlated with changes in the inorganic anion pool. Overall organic acid concentrations decreased by an average of 93% over 11 month period, indicating a substantial geochemical evolution of the organic acid pool over this time frame. Measurements dissolved oxygen and ORP supported the existence of an aerobic region at the base of the wetland, followed by an anaerobic region in the strata above. Significant nitrate and sulfate reduction in the anaerobic region occurred in unison with the emergence of higher concentrations of lactate and formate. Results indicate the reducing conditions and substrates required to support reductive dechlorination of chlorinated ethenes were present in the subsurface of the wetland.

Download or read book Chlorinated Solvent Source Zone Remediation written by Bernard H. Kueper and published by Springer Science & Business. This book was released on 2014-04-22 with total page 759 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this book is to help engineers and scientists better understand dense nonaqueous phase liquid (DNAPL) contamination of groundwater and the methods and technology used for characterization and remediation. Remediation of DNAPL source zones is very difficult and controversial and must be based on state-of-the-art knowledge of the behavior (transport and fate) of nonaqueous phase liquids in the subsurface and site specific geology, chemistry and hydrology. This volume is focused on the characterization and remediation of nonaqueous phase chlorinated solvents and it is hoped that mid-level engineers and scientists will find this book helpful in understanding the current state-of-practice of DNAPL source zone management and remediation.

Download or read book In Situ Remediation of Chlorinated Solvent Plumes written by Hans F. Stroo and published by Springer Science & Business Media. This book was released on 2010-09-10 with total page 807 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Coastal Hydrogeology written by Jimmy Jiao and published by Cambridge University Press. This book was released on 2019-05-09 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: Offers a comprehensive volume discussing groundwater problems in coastal areas, spanning fundamental science to practical water management.

Download or read book A Comparison of Modeling Approaches in Simulating Chlorinated Ethene Removal in a Constructed Wetland by a Microbial Consortia written by Jason S. Campbell and published by . This book was released on 2002-03 with total page 113 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this study is to compare different approaches to modeling the reductive dechlorination of chlorinated ethenes in the anaerobic region of an upward flow constructed wetland by microbial consortia. A controlled simulation experiment that compares three different approaches to modeling the degradation of chlorinated ethenes in wetland environments is conducted and investigates how each of the modeling approaches affect simulation results. Concepts like microbial growth in the form of a biofilm and spatially varying contaminant concentrations bring the validity of the CSTR assumption into question. These concepts are incorporated into the different modeling approaches to evaluate the CSTR assumption. Model simulations show that spatially varying contaminant concentrations have a significant effect on contaminant effluent concentrations. Additionally, the significance of the incorporation of a biofilm concept depends on the time characteristics of both diffusive mass transport and reaction kinetics.

Download or read book Natural Attenuation of Chlorinated Solvent Ground Water Plumes Discharging Into Wetlands written by and published by . This book was released on 2002 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: A substantial number of chlorinated solvent ground-water plumes at hazardous waste sites may potentially discharge into ecologically sensitive wetland environments. Although chlorinated solvents tend to be relatively resistant to degradation within most aquifer systems, rapid and complete transformations can occur within the organic-rich reducing environment typical of wetland sediments, suggesting that monitored natural attenuation may be an effective remediation option for discharges into wetlands. A previous study by the U.S. Geological Survey (USGS) in a freshwater tidal wetland at Aberdeen Proving Ground (APG), Maryland, showed complete attenuation of chlorinated solvents before the wetland surface or creek was reached. A collaborative study by the USGS and the Air Force Research Laboratory under the Department of Defense Environmental Security Technology Certification Program (ESTCP) was conducted to determine if the natural attenuation of chlorinated solvents that occurs at the APG wetland site can occur at wetland sites located in different hydrogeologic environments and to assist in the transfer of this technology to other potential users. The objectives of this ESTCP demonstration project were to (1) assess and compare the extent of natural attenuation of chlorinated solvent at three wetland sites in different hydrogeologic environments; (2) to demonstrate and compare different methods of sampling and analysis for collecting the site data needed to evaluate natural attenuation in wetlands; and (3) to develop a technical protocol for the assessment of natural attenuation of chlorinated solvent plumes discharging into wetlands.

Download or read book Chemical and Structural Characterization of Material Formed in Constructed Wetlands Treated with Metal Based Coagulants and Their Effects on Wetland Vegetation written by Yan Ling Liang and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Sacramento-San Joaquin Delta (Delta) provides two-thirds of the drinking water used by Californians. Various issues affecting water quality have resulted from the regions agricultural activities. There is a need to mitigate the effect of agricultural practices to meet ever increasingly strict regulations on drinking water quality and in conserving this resource. An on-site coagulation wetland system was implemented to reduce dissolved organic carbon (DOC) in the agricultural drainage water being released back into the Delta channels. This model wetland system was used to assess DOC removal effectiveness, coagulated material stability and vegetative health impacts of on-site coagulation water treatment on Delta islands. Two coagulation treatments were studied, polyaluminum chloride (PAC) and ferric sulfate (FeSO4), and compared to a control treatment, which did not receive any coagulants. Results from these investigations provided a better understanding of the substances produced by on-site coagulation systems and the systems’ viability to be used for water treatment and carbon sequestration purposes without negatively impacting native Typha spp. populations. The first study investigated the nature of control material, PAC and FeSO4 coagulated materials being formed upon coagulation and collected in sediment traps and at inflows to tests the hypothesis that PAC and FeSO4 coagulation will result in coagulated materials that are similar to control material in size, component and structure but differ in elemental nature. The second study investigated the bonding nature of coagulant metals to organic matter and comparisons were made to control material (inflow flocs and sediment trap material). This second study tested the hypotheses that PAC and FeSO4 coagulated materials (sediment trap material and inflow flocs) will consist of the similar functional groups as control material, and both coagulants will bind to organic matter through similar mechanisms. The last study investigated the effect of coagulated material accumulation on Typha spp. populations within the constructed wetlands to test the hypotheses that coagulation will not reduce nutrient availability to support Typha growth over two growing cycles and soil nutrient content will be correlated to plant biomass, allometrics and nutrient content. These studies demonstrated that control material, PAC and FeSO4 coagulated material were similar in their component composition and particle size, but differed slightly in structural and chemical aspects. PAC sediment trap material was found to be more stable compared to FeSO4 sediment trap material under conditions studied. PAC sediment trap material was unlikely to re-disperse back into solution when subjected to long term reducing redox conditions. Coagulation treatment with PAC and FeSO4 were demonstrated to be viable options for on-site water treatment that will not disrupt the normal growth of Typha populations over a two-year period. This body of research supported the use of both PAC and FeSO4 for the use in on-site coagulation wetland systems for the dual purpose of wetland restoration and water treatment for a continuous period of two years. These coagulation systems represent a feasible option for complying with agricultural drainage water regulations and in helping improve the water quality of the Delta channels.

Download or read book Evaluation of Chlorinated Solvent Removal Efficiency Among Three Wetland Plant Species written by Jun Yan and published by . This book was released on 2006 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Assessment of in Situ Biodegradation of Chlorinated Solvents in Aquifers and Constructed Wetlands Using an Integrative Approach written by Gwenaël Imfeld and published by . This book was released on 2009 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Characterization And Monitoring Of Natural Attenuation Of Chlorinated Solvents In Ground Water written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Assessment of in Situ Biodegradation of Chlorinated Solvents in Aquifers and Constructed Wetlands Using an Integrative Approach written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: