Download or read book Remediation of Chromium VI in the Vadose Zone written by Min Ahn and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Immobilization and detoxification of chromium in the vadose zone is made possible by the existence of an effective reductant, SO2, that exists in a gaseous form at room temperature. Experimental studies were designed to characterize stoichiometry and kinetics of chromium reduction both in aqueous solutions at pH values near neutrality and in soil. First, batch experiments and elemental analyses were conducted to characterize the stoichiometry and kinetics of Cr(VI) reduction in water. The stoichiometric ratio of S(IV) removed to Cr(VI) removed ranged between 1.6 and 1.8. The overall reaction is believed to be the result of a linear combination of two reactions in which dithionate is an intermediate and sulfate is the stable oxidized product. The reaction was also rapid, with the half-time of about 45 minutes at pH 6 and about 16 hours at pH 7. A two-step kinetic model was developed to describe changes in concentrations of Cr(VI), S(IV), and S(V). Nonlinear regression was applied to obtain the kinetic parameters. The rate of reaction was assumed to be second-order with respect to [Cr(VI)] and first-order with respect to [S(IV)], and [S(V)]. The values for the rate coefficient for the first reaction (k1) were found to be 4.5 ("10%), 0.25 ("9.4%) (mM-2h-1) at pH 6 and 7, respectively. The values of the rate coefficient for the second reaction (k2) were 25 ("29%), 1.1 ("30%) (mM-2h-1) at pH 6 and 7, respectively. The reaction rate decreased as pH increased. Experiments showed that the rate at pH 7 was lower than that at pH 6 by one order of magnitude. Second, batch experiments and elemental analyses were conducted to characterize the stoichiometry and kinetics of Cr(VI) reduction in soil. The stoichiometric ratio of S(IV) removed to Cr(VI) removed was almost 2, which is slightly higher than that for the reaction in water. This higher value may be due to S(IV) oxidation by soil-derived Fe(III). The reaction was rapid, with the half-time less than 2 minutes, which is faster than in water. The rate coefficients, k1 and k2, were 22 ("41%) and 13 ("77%) (M-2h-1), respectively.
Download or read book In Situ Treatment of Soil and Groundwater Contaminated with Chromium written by National Risk Management Research Laboratory (U.S.) and published by . This book was released on 2000 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Project Work Plan Chromium Vadose Zone Characterization and Geochemistry written by Calvin C. Ainsworth and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The major objectives of the proposed study are to 1) determine the leaching characteristics of Cr(VI) from contaminated sediments collected from 100 area spill sites, 2) elucidate possible Cr(VI) mineral and/or chemical associations that may be responsible for Cr(VI) retention in the Hanford site 100 areas through the use of i) macroscopic solubility studies and ii) microscale characterization of contaminated sediments, and 3) from these data construct a conceptual model of Cr(VI) geochemistry in the Hanford 100 area vadose zone. These objectives are based on locating and obtaining contaminated sediment with depth and at varying Cr(VI) concentrations as we hypothesize that mineral/chemical-Cr(VI) associations should be related to the total Cr concentration and other master geochemical variables (e.g., pH, counter-cation type and concentration, and water content). In addressing these objectives, additional benefits accrued will be (1) a fuller understanding of Cr(VI) entrained in the vadose zone that will that can be utilized in modeling potential Cr(VI) source terms, and 2) accelerating the Columbia River 100 area corridor cleanup by developing remedial action based on a fundamental understanding of Cr(VI) vadose zone geochemistry.
Download or read book Handbook of Groundwater Remediation using Permeable Reactive Barriers written by David Naftz and published by Academic Press. This book was released on 2002-10-17 with total page 569 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the last century and a half, groundwaters have become contaminated by a growing number of organic and inorganic substances ranging from petroleum-derived hydrocarbons to radioactive compounds, to cancer-causing hexavalent chromium. The importance of uncontaminated groundwater for agriculture, human consumption, and the environmental health of ecosystems is paramount to the health and productivity of industrial society. Water scientists and managers are focused on developing cost-effective methods to reverse this trend.Several methodologies have been developed, however few are as cost-effective as the use of readily available materials, such as iron and organic compost, for absorbing and isolating contaminants within the matrix of a permeable barrier. The Handbook of Groundwater Remediation using Permeable Reactive Barriers presents readers with this latest technology and developments within four main sections:1. Innovations in Design, Construction, and Evaluation of PRBs2. Development of Reactive Materials3. Evaluations of Chemical and Biological Processes4. Case Studies of Permeable Reactive Barrier InstallationsThe Handbook is one of the first references specifically on this topic. It is an excellent fit for graduate students entering this emerging field as well as professionals conducting research or implementing this technology.
Download or read book Chromium VI Handbook written by Jacques Guertin and published by CRC Press. This book was released on 2004-12-28 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt: Put together by a team of scientists, engineers, regulators, and lawyers, the Chromium(VI) Handbook consolidates the latest literature on this topic. The broad scope of this book fills the need for a comprehensive resource on chromium(VI), improving the knowledge of this contaminant at a time when the extent and degree of the problem is still being
Download or read book Abiotic in Situ Technologies for Groundwater Remediation Conference written by and published by . This book was released on 2000 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Remediation of Chromium Contaminated Soil Theory and Practice written by Weichun Yang and published by Springer Nature. This book was released on 2023-10-03 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: In accordance with the global needs of heavy metal-contaminated site remediation, this book systematically introduces the latest theories and technical achievements of microbial and chemical treatment for the chromium pollution in the chromium slag and chromium-contaminated soil, combined with the author's research achievements over the decades. The book focuses on the biological and chemical behavior of chromium in soil, microbial, and chemical remediation for the chromium-contaminated soil and the cases of chromium-contaminated site remediation project. This book is used by the scientific researchers and engineering technicians engaged in chromium chemical industry and environmental protection. It is also used as a textbook and reference book for graduate students in environmental science and engineering, soil science, chemistry and chemical engineering, and other related fields.
Download or read book Results from Recent Science and Technology Investigations Targeting Chromium in the 100D Area Hanford Site Washington Usa written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Sodium dichromate was used in Hanford's 100D Area during the reactor operations period of 1950 to 1964 to retard corrosion in the reactor cooling systems. Some of the sodium dichromate was released to the environment by spills and/or leaks from pipelines used to deliver the chemical to water treatment plants in the area. As a result, hexavalent chromium [Cr(VI)] has migrated through the vadose zone to the groundwater and contaminated nearly 1 km2 of groundwater to above the drinking water standard of 48 [mu]g/L. Three technology tests have recently been completed in this area to characterize the source area of the plumes and evaluate alternative methods to remove Cr(VI) from groundwater. These are (1) refine the source area of the southern plume; (2) test electrocoagulation as an alternative groundwater treatment technology; and (3) test the ability to repair a permeable reactive barrier by injecting micron or nanometer-size zero-valent iron (ZVI). The projects were funded by the US Department of Energy as part of a program to interject new technologies and accelerate active cleanup. Groundwater monitoring over the past 10 years has shown that Cr(VI) concentrations in the southern plume have not significantly diminished, strongly indicating a continuing source. Eleven groundwater wells were installed in 2007 and 2008 near a suspected source area and monitored for Cr(VI) and groundwater levels. Interpretation of these data has led to refinement of the source area location to an area of less than 1 hectare (ha, 2.5 acres). Vadose zone soil samples collected during drilling did not discover significant concentrations of Cr(VI), indicating the source is localized, with a narrow wetted path from the surface to the water table. Electrocoagulation was evaluated through a pilot-scale treatability test. Over 8 million liters of groundwater were treated to Cr(VI) concentrations of ≤20 [mu]g/L. The test determined that this technology has the potential to treat Cr(VI) to these low levels, but system reliability and operational complexity rendered electrocoagulation less cost effective than the baseline technology of ion exchange. Laboratory and field tests were conducted to evaluate the practicality of injecting ZVI into the aquifer to increase the lifespan and effectiveness of an existing permeable reactive barrier. From a database of 30 ZVI materials, 6 were chosen and tested in the laboratory to determine their geochemical and physical performance under simulated 100D aquifer conditions. The best-performing ZVI was injected into the aquifer and met the primary goals of communicating the iron at least 7 meters from the injection point and reducing the aquifer to transform mobile Cr(VI) to trivalent chromium Cr(III), which is effectively immobile in the aquifer.
Download or read book Innovative Measures for Subsurface Chromium Remediation written by and published by . This book was released on 1997 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geochemical Characterization of Chromate Contamination in the 100 Area Vadose Zone at the Hanford Site written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: At the Hanford Site, chromate was used throughout the 100 Areas (100-B, 100-C, 100-D/DR, 100-F, 100-H, and 100 K) as a corrosion inhibitor in reactor cooling water. Chromate was delivered in rail cars, tanker trucks, barrels, and local pipelines as dichromate granular solid or stock solution. In many occasions, chromate was inevitably discharged to surface or near-surface ground through spills during handling, pipeline leaks, or during disposal to cribs. The composition of the liquids that were discharged is not known and it is quite possible that Cr(VI) fate and transport in the contaminated sediments would be a function of the chemical composition of the waste fluids. The major objectives of this investigation which was limited in scope by the financial resources available, were to 1) determine the leaching characteristics of hexavalent chromium [Cr(VI)] from contaminated sediments collected from 100-D Area spill sites; 2) elucidate possible Cr(VI) mineral and/or chemical associations that may be responsible for Cr(VI) retention in the Hanford Site 100 Areas through the use of macroscopic leaching studies, and microscale characterization of contaminated sediments; and 3) provide information to construct a conceptual model of Cr(VI) geochemistry in the Hanford 100 Area vadose zone that can be used for developing options for environmental remediation. The information gathered from this research effort will help to further improve our understanding of Cr(VI) behavior in the vadose zone and will also help in accelerating the 100 Area Columbia River Corridor cleanup by providing valuable information to develop remedial action based on a fundamental understanding of Cr(VI) vadose zone geochemistry. A series of column experiments were conducted with contaminated sediments to study Cr(VI) desorption patterns. Column experiments used the field size fraction of the sediment samples and a simulated Hanford Site groundwater solution. Periodic stop flow events were applied to evaluate the change in elemental concentration during time periods of no flow and greater fluid residence time. Sediments were characterized for the spatial and mineralogical associations of the contamination using some microscale techniques such as X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy.
Download or read book Bioremediation of Contaminated Soils written by Donald L. Wise and published by CRC Press. This book was released on 2000-06-09 with total page 930 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume focuses on innovative bioremediation techniques and applications for the cleanup of contaminated media and sites. It includes quantitative and design methods that elucidate the relationships among various operational parameters, and waste chemistry that defines the cost effectiveness of bioremediation projects. It also presents numerical models.
Download or read book Remediation of Hazardous Waste Contaminated Soils written by DonaldL. Wise and published by Routledge. This book was released on 2018-10-03 with total page 952 pages. Available in PDF, EPUB and Kindle. Book excerpt: ""This unique, single-source reference offers a thorough treatment of the remediation of soils contaminated by hazardous wastes and the scientific and engineering issues that must be addressed in creating practical solutions for their reclamation.
Download or read book Interfacial Reduction Oxidation Mechanisms Governing Fate and Transport of Contaminants in the Vadose Zone written by Jeff Terry and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The mobility of many contaminants is redox sensitive and thus related to the reduction oxidation characteristics of the environment. Immobilization of certain contaminants (e.g., chromium, uranium, and technetium) can be achieved by reducing the contaminant. One remediation approach to achieving this is the application of diluted hydrogen sulfide gas mixtures, which may have particular value in vadose zone applications. Previous work has shown this approach to be viable for Cr(VI) remediation of soil waste sites. The primary objective of the current research is to assess the potential of in situ gaseous treatment to the immobilization of U(VI) and Tc(VII). This work also addresses basic science aspects of understanding the redox-related aspects of the mobility of these contaminants in the natural environment, thus providing a mechanistic-based understanding needed to successfully achieve remediation.
Download or read book Low Level Hexavalent Chromium Treatment Options written by Philip Brandhuber and published by American Water Works Association. This book was released on 2005-07-31 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: In February 1999, the California Office of Environmental Health Hazard Assessment issued a Public Health Goal (PHG) for total chromium of 2.5 μg/L. The PHG, based on a 10^6 risk level for 0.2 μg/L hexavalent chromium [Cr(VI)], was 40 times less than the USEPA's contaminant MCL of 100 μg/L for total chromium [Cr(III) ] Cr(VI)]. The success of the movie Erin Brockovich, which popularized a groundwater chromium pollution lawsuit in Hinkley, California, sensitized the public to the health hazards of chromium in drinking water. In 2001, the California state legislature passed a bill requiring the California Department of Health Services to adopt an MCL for Cr(VI). All of these actions must be viewed from the perspective that, at the time, no technology had been demonstrated to be effective at treating chromium to concentrations consistent with the total chromium PHG or the Cr(VI) 10^6 risk level of 0.2 μg/L. The purpose of this report was to present the results of this partnership study, which included an analysis of chromium occurrence and co-occurrence, an evaluation of Cr(VI) removal technologies, and an examination of chromium oxidation and reduction chemistry. This study investigated nearly all of the potential methods of controlling Cr(VI) either through the use of technologies that remove Cr(VI) directly (adsorption, anion exchange, membrane filtration) or those that remove the reduced form of chromium, Cr(III) (precipitation with membranes or coagulation and precipitation with conventional or membrane filters). These technologies were investigated using laboratory-scale testing methods, including batch isotherm tests, bench membrane systems, flow-through mini-columns, and jar testing techniques. For most technologies, controlled water matrices were used to screen performance. Selected technologies were further assessed using natural groundwater matrices from the Los Angeles Department of Water and Power and the Glendale Water and Power groundwater facilities.
Download or read book In Situ Recovery Remediation of Metals written by Drummond Earley III and published by Society for Mining, Metallurgy & Exploration. This book was released on 2020-03-27 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current trends in mining are driving the demand for subsurface extraction technologies with low surface impacts that protect surface and ground water. Moreover, the necessity for sustainable mineral extraction technologies has increased as regulatory restrictions and technical challenges to traditional mining grow with production from deeper and deeper remaining metal resources. This book provides a state-of-the-art synopsis of in situ metal recovery and remediation technologies based on both research and commercial projects. In situ recovery uses fluid-based metal dissolution and recovery to extract one or more commodities from a largely intact rock mass using similar processes that create ore deposits. The fluid is circulated through ore by gravity and/or pumps using injection and recovery wells. A processing facility is usually established at the surface of the operation to extract the commodity of interest. The barren fluid is then recirculated back into the recovery circuit. In situ remediation uses similar wellfield technology and chemical processes to stabilize metal contaminants by injecting agents that form stable solids or less toxic species when combined with a contaminant. The fluid depleted in the stabilizing agent is then pumped back to the surface and regenerated. In situ mining or recovery has been successfully applied to several commodities, including uranium, sulfur, evaporites, and copper, which have favorable chemical properties and deposit types for in situ recovery.
Download or read book Hexavalent Chromium Remediation by Zero Valent Iron and Calcium Polysulfide written by Tongzhou Wang and published by . This book was released on 2009 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Groundwater Contamination and Remediation written by Timothy D. Scheibe and published by MDPI. This book was released on 2018-12-07 with total page 185 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Groundwater Contamination and Remediation" that was published in Water
