Download or read book A Plan for Study of Natural and Man made Hexavalent Chromium Cr VI in Groundwater Near a Mapped Plume Hinkley California written by John A. Izbicki and published by . This book was released on 2016 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Natural and Anthropogenic human made Hexavalent Chromium Cr VI in Groundwater Near a Mapped Plume Hinkley California written by and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Natural Attenuation of Hexavalent Chromium in Ground Water and Soils written by Carl D. Palmer and published by . This book was released on 1994 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Investigation of Hexavalent Chromium Flux to Groundwater at the 100 C 7 written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Deep excavation of soil has been conducted at the 100-C-7 and 100-C-7:1 waste sites within the 100-BC Operable Unit at the Department of Energy (DOE) Hanford Site to remove hexavalent chromium (Cr(VI)) contamination with the excavations reaching to near the water table. Soil sampling showed that Cr(VI) contamination was still present at the bottom of the 100-C-7:1 excavation. In addition, Cr(VI) concentrations in a downgradient monitoring well have shown a transient spike of increased Cr(VI) concentration following initiation of excavation. Potentially, the increased Cr(VI) concentrations in the downgradient monitoring well are due to Cr(VI) from the excavation site. However, data were needed to evaluate this possibility and to quantify the overall impact of the 100-C-7:1 excavation site on groundwater. Data collected from a network of aquifer tubes installed across the floor of the 100-C-7:1 excavation and from temporary wells installed at the bottom of the entrance ramp to the excavation were used to evaluate Cr(VI) releases into the aquifer and to estimate local-scale hydraulic properties and groundwater flow velocity.
Download or read book Draft Initial Study mitigated Negative Declaration written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The Soquel Creek Water District (District) proposes to construct a well head water treatment system to treat naturally-occuraing hexavalent chromium (chromiun-6) (Project). The Project will bring the District into compliance with the California Sate Water Resource Control Board (SWRCB) Division of Drinking Water's (DDW) final maximum contaminant level (MCL) of 10 micrograms per liter (ug/L) or part per billion (ppb) for chromium-6 ... The Project site is located in unincorporated Santa Cruz County in between the communities of Rio Del Mar and La Selva Beach (See Figure 2: Project overview). The Project consists of a new treatment facility at the District's Bonita well site at 1500 Bonita Drive (referred to as treatment facility site" -- page 1-1.
Download or read book Hexavalent Chromium Removal Using Anion Exchange and Reduction with Coagulation and Filtration written by and published by American Water Works Association. This book was released on 2007 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Following the discovery of high hexavalent chromium Cr(VI) concentrations in several groundwater extraction wells and plumes heading toward production wells, the City of Glendale, California devoted significant resources to identify effective Cr(VI) removal technologies from drinking water. Glendale initiated a 4 phase research program: Phase 1- Bench-scale study that improved the understanding of fundamental chromium chemistry and screened promising treatment technologies. Phase 2 - Pilot scale study that evaluated Cr(VI) treatment technologies under field conditions. Phase 3 - Bridge project and demonstration scale study to further test a promising technology, to construct a demonstration-scale treatment facility, and finalise the technology and cost evaluation. Phase 4 - Full scale implementation. This reports presents the findings and results of phase 3.
Download or read book A Field Laboratory and Modeling Study of Natural Attenuation Processes Affecting the Fate and Transport of Hexavalent Chromium in a Redox Variable Groundwater Environment written by Lucas Ammi Hellerich and published by . This book was released on 2004 with total page 560 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Meeting the New California MCL for Hexavalent Chromium with Strong Base Anion Exchange Resin written by Xue Li and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Following a public health goal (PHG) of 0.02 [mu]g/L set in 2011 in California, a hexavalent chromium (Cr(VI)) maximum contaminant level (MCL) of 10 [mu]g/L became effective on July 1, 2014. The potential non-compliance of several hundred potable water systems is driving the search for cost-effective treatment techniques and was the motivating force behind this research. One of the techniques to remove Cr(VI) is Strong Base Anion Exchange (SBA-IX). Until recently, SBA-IX studies have been conducted mainly with high concentrations of Cr(VI) (50-4000 mg/L) on wastewater or synthetic (industrial) water. Additionally, no comprehensive studies have been conducted with respect to the management of regeneration brines following chromium removal. In this study, the chromium removal performance of flow-through columns packed with commercially available resins was quantitatively investigated with/ at different potable groundwater sources, empty bed contact times, and hydraulic loading rates. The bench tests were also scaled up to field tests for comparison of chromium removal performance. Extended regeneration cycles with fresh brine were conducted to obtain a complete picture of the resin performance after repeated usages. Direct brine reuse to minimize the disposal volumes of potentially hazardous waste was tested. While SBA-IX is a feasible option for chromium removal from potable water sources, the application of SBA-IX is sometimes challenging due to lack of effective treatment and /or disposal options of the hazardous brine. As direct brine reuse minimizes the waste brine volume, the study of brine management options aimed to reduce the hazardous characteristics of the brine. One alternative regenerant, i.e., sodium bicarbonate, to replace sodium chloride was studied for its elution efficiency of chromium during regeneration and its affinity for chromium during ion exchange. Brine treatment with metal salts (i.e., ferrous sulfate), reductive media (i.e., sulfur modified iron), and weak base anion exchange (WBA-IX) resin was investigated for their capacity for chromium and feasibility to reduce the hazardous characteristics of the regeneration brine. By investigating three aspects of the SBA-IX technique, i.e., removal of low-level chromium from natural groundwater, regeneration of the exhausted resin, and management of the waste brine, this study aims to provide a comprehensive understanding of the SBA-IX.
Download or read book Assessment of Hexavalent Chromium Natural Attenuation for the Hanford Site 100 Area written by and published by . This book was released on 2015 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hexavalent chromium (Cr(VI)) plumes are present in the 100 Area at the Hanford Site. Remediation efforts are under way with objectives of restoring the groundwater to meet the drinking-water standard (48 æg/L) and protecting the Columbia River by ensuring that discharge of groundwater to the river is below the surface-water quality standard (10 æg/L). Current remedies include application of Pump-and-Treat (P & T) at the 100-D, 100-H, and 100-K Areas and Monitored Natural Attenuation (MNA) at the 100-F/IU Area. Remedy selection is still under way at the other 100 Areas. Additional information about the natural attenuation processes for Cr(VI) is important in all of these cases. In this study, laboratory experiments were conducted to demonstrate and quantify natural attenuation mechanisms using 100 Area sediments and groundwater conditions.
Download or read book A Steady state Model for Hexavalent Chromium Reduction in Simulated Biological Reactive Barrier written by Phalazane Johanna Mtimunye and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Biological remediation of Cr(VI) contaminated soil and groundwater is an emerging field. In this study, the in situ bioremediation technology for treating Cr(VI) contaminated groundwater aquifers was evaluated using a laboratory microcosm system. The study was conducted using columns with five equally spaced intermediate sampling ports along the length to facilitate finite difference modelling of the Cr(VI) concentration profile within the column. Cr(VI) concentration was continuously measured in the influent, in five equally spaced intermediate ports within the column and in the effluent port. The change or the shift in microbial community within the inoculated column was also monitored due to exposure to toxic conditions after seven weeks of operation using the 16S rRNA genotype fingerprinting method. The effect of introducing a natural carbon source (sawdust) in inoculated columns in comparison with the performance of sterile controls under various loading conditions was also evaluated. Near complete Cr(VI) removal was achieved in an inoculated carbon source reactor, whereas only 69.5% of Cr(VI) removal was achieved in an inoculated column without an added carbon source after 4 days of operation at 20 mg/L. In a sterile control reactor less than 2% of Cr(VI) was removed after 4 days of operation at 20 mg/L. Experimental cores demonstrated a successful Cr(VI) reduction process in the simulated microbial barrier system that was evaluated internally. The model that simulates Cr(VI) removal and transport in the subsoil environment was developed. The Cr(VI) mass balance model across the reactor that accounts for the flow characteristics and biological removal mechanism successfully captured the trends of Cr(VI) response profiles under quasi-steady state conditions for different loading conditions. This study demonstrate the potential of applying effective Cr(VI) reducers in the reactive barrier systems to contain or attenuate the spread of Cr(VI) contaminant in groundwater aquifer systems. The finite difference model developed in this study to evaluate the behaviour of Cr(VI) in the reactor could contribute towards improved designs of future in situ bioremediation systems that can be implemented for remediation of Cr(VI) on site.
Download or read book Geochemical Controls on Chromium Occurrence Speciation and Treatability written by Janet G. Hering and published by International Water Assn. This book was released on 2005-01-01 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this project was to improve the scienc
Download or read book Hexavalent Chromium written by U.S. Department of Labor and published by CreateSpace. This book was released on 2014-03-15 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication is intended to supplement OSHA's Small Entity Compliance Guide for the Hexavalent Chromium Standards published in 2006 and to give readers an overview of the provisions and requirements of the Hexavalent Chromium standards for general industry (29 CFR 1910.1026), shipyards (29 CFR 1915.1026), and construction (29 CFR 1926.1126). Hexavalent chromium (Cr(VI)) is a toxic form of the element chromium. Hexavalent chromium is rarely found in nature and is generally man-made. Cr(VI) is widely used in pigments, metal finishing (electroplating), wood preservatives and fungicides, and in chemical synthesis as an ingredient and catalyst. Hexavalent chromium may also be present in fumes generated during the production or welding of chrome alloys. Chromium metal is often alloyed with other metals or plated on metal and plastic substrates to improve corrosion resistance and provide protective coatings. The steel industry is a major consumer of chromium metal in the production of stainless steel. Since 2000, there has been a decline in the use of chromates in pigments for paints and coatings; printing inks; ceramic, glass and construction materials; roofing and plastics. Employers are substituting less toxic inorganic and organic pigments where possible (SRI Consulting, 2008). Workplace exposure to Cr(VI) may cause the following health effects: lung cancer in workers who breathe airborne Cr(VI); irritation or damage to the nose, throat and lungs (respiratory tract) if Cr(VI) is inhaled; and irritation or damage to the eyes and skin if Cr(VI) contacts these organs. Workers can inhale airborne Cr(VI) as a dust, fume or mist while, among other things, producing chromate pigments, dyes and powders (such as chromic acid and chromium catalysts); working near chrome electroplating; performing hot work and welding on stainless steel, high chrome alloys and chrome-coated metal; and applying and removing chromate-containing paints and other surface coatings. Skin exposure can occur while handling solutions, coatings and cements containing Cr(VI).
Download or read book Proposed Hexavalent Chromium Control Plan Staff Report written by and published by . This book was released on 1988 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Occurrence and Treatment of Hexavalent Chromium and Arsenic in Arizona Municipal and Industrial Waters written by Alexandra Bowen and published by . This book was released on 2014 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: Arsenic (As) and chromium (Cr) occur naturally in AZ surface and groundwaters, pose different health impacts, and exhibit different treatment efficacies. Hexavalent chromium (Cr(VI)) has newly recognized human health concerns, and state and federal agencies are evaluating a low Cr(VI)-specific maximum contaminant level (MCL) for drinking water. Occurrence of Cr and As in municipal drinking waters and industrial cooling tower waters was quantified by grab samples and compared with sampling results obtained from a new passive sampler developed specifically for Cr(VI). Cr(VI) and As concentrations in groundwater used for cooling tower make-up water concentrations were ~3 ppb and ~4 ppb, respectively, and were concentrated significantly in blowdown water (~20 ppb and ~40 ppb). Based upon pending Cr(VI), As, and other metal regulations, these blowdown waters will need routine monitoring and treatment. Cr(VI) concentrations in a water treatment plant (WTP) raw and finished water samples varied from 0.5 and 2 ppb for grab samples collected every 4 hours for 7 consecutive days using an ISCO sampler. The development of an ion exchange (IX) based passive sampler was validated in the field at the WTP and yielded an average exposure within 1 standard deviation of ISCO sampler grab data. Sampling at both the WTP and cooling towers suggested sources of Cr(III) from treatment chemicals or wood preservatives may exist. Since both facilities use chlorine oxidants, I quantified the apparent (pH=5) second-order rate constant for aqueous chlorine (HOCl/OCl- ) with Cr(III) to form Cr(VI) as 0.7 M-1s-1. Under typical conditions (2 ppb Cr(III) ; 2 mg/L Cl2) the half-life for the conversion of Cr(III) to the more toxic form Cr(VI) is 4.7 hours. The occurrence studies in AZ and CA show the Cr(VI) and As treatment of groundwaters will be required to meet stringent Cr(VI) regulations. IX technologies, both strong base anion (SBA) and weak base anion (WBA) resin types were screened (and compared) for Cr removal. The SBA IX process for As removal was optimized by utilizing a reactive iron coagulation and filtration (RCF) process to treat spent IX brine, which was then reused to for SBA resin regeneration.
Download or read book Alternatives for Managing the Nation s Complex Contaminated Groundwater Sites written by National Research Council and published by National Academies Press. This book was released on 2013-02-27 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: Across the United States, thousands of hazardous waste sites are contaminated with chemicals that prevent the underlying groundwater from meeting drinking water standards. These include Superfund sites and other facilities that handle and dispose of hazardous waste, active and inactive dry cleaners, and leaking underground storage tanks; many are at federal facilities such as military installations. While many sites have been closed over the past 30 years through cleanup programs run by the U.S. Department of Defense, the U.S. EPA, and other state and federal agencies, the remaining caseload is much more difficult to address because the nature of the contamination and subsurface conditions make it difficult to achieve drinking water standards in the affected groundwater. Alternatives for Managing the Nation's Complex Contaminated Groundwater Sites estimates that at least 126,000 sites across the U.S. still have contaminated groundwater, and their closure is expected to cost at least $110 billion to $127 billion. About 10 percent of these sites are considered "complex," meaning restoration is unlikely to be achieved in the next 50 to 100 years due to technological limitations. At sites where contaminant concentrations have plateaued at levels above cleanup goals despite active efforts, the report recommends evaluating whether the sites should transition to long-term management, where risks would be monitored and harmful exposures prevented, but at reduced costs.
