Cyclodextrin‐enhanced remediation of organic and metal contaminants in porous media and groundwater

Heavy metals and toxic organic contaminants are found at numerous industrial and military sites. The generally poor performance of conventional pump‐and‐treat schemes has made the development of improved methods for contaminated site remediation a significant environmental priority. One such innovative method is cyclodextrin‐enhanced flushing of the contaminated porous media and groundwater. Cyclodextrin is a glucose‐based molecule that is produced on industrial scales by microorganisms. Over the last years, several cyclodextrin derivatives have received extensive research interest. It was shown that cyclodextrins can significantly enhance the solubility of toxic organics, and in some cases, heavy metals and radioactive isotopes. As a sugar, cyclodextrin is considered relatively non‐toxic to humans, plants, and soil microbes. Thus, there are minimal health‐related concerns associated with the injection of cyclodextrin into the subsurface, which is an inherent advantage for use of cyclodextrins as a remediation agent. This paper provides a review of the available literature concerning use of cyclodextrin for remediation of groundwater and soil.     

Fate and behavior of metal(loid) contaminants in an organic matter-rich shooting range soil: Implications for remediation

This study investigates the fate and behavior of lead (Pb), copper (Cu), antimony (Sb), and arsenic (As) in a shooting range soil. The soil samples were collected from the surface (0–15 cm) and the subsurface (15–40 cm and 40–55 cm) of a grassy and wood chip covered impact area behind a firing position. Optical microscopy images indicate significant amounts of corroded bullet fragments and organic wood chips in the surface soil. Analysis by X-ray powder diffraction (XRPD) and scanning electron microscopy electron dispersive X-ray spectroscopy (SEM-EDS) showed that metallic Pb was transformed into lead oxides (litharge PbO and massicot PbO) and lead carbonates (hydrocerussite Pb₃(CO₃)₂(OH)₂, cerussite PbCO₃, and plumbonacrite Pb₅(CO₃)₃O(OH)₂). Rietveld quantification indicated the surface soil contained 14.1% metallic Pb, 17.9% hydrocerussite, 5.2% plumbonacrite, 5.9% litharge, and 3.9% massicot on a dry weight basis, or a total of 39.7% Pb, far in excess of lead concentrations typically found in US shooting range soils. Metallic Cu (bullet jacket material) appeared stable as no secondary minerals were detected in the surface soil. As and Sb concentrations were on the order of 1,057 mg/kg and 845 mg/kg respectively. The elevated soil pH coupled with high organic carbon content is thought to have caused downward migration of metals, especially for Pb, since 4,153 mg Pb/kg was observed at a depth of 55 cm. More than 60% of Pb was concentrated in the coarse soil (> 0.425 mm) fraction, suggesting soil clean-up possible by physical soil washing may be viable. The concentrations of Pb, As, and Sb in the toxicity characteristic leaching procedure (TCLP) extracts were 8,869 mg/L, 6.72 mg/L, and 6.42 mg/L respectively, were above the USEPA non-hazardous regulatory limit (As and Pb) of 5 mg/L. The elevated Sb and As concentrations draw concern because there is historically limited information concerning these metals at firing ranges and several values exceeded local soil cleanup criteria. As the high Pb concentrations appeared to be linked to the presence of organic-rich berm cover materials, the use of wood chips as berm cover to prevent soil erosion requires reconsideration as a shooting range management practice.     

Radiolytic decomposition of environmental contaminants and site remediation using an electron accelerator

Halogenated and nonhalogenated hydrocarbon contaminants are currently found in natural waterways, groundwater, and soils as a result of spills and careless disposal practices. The development of proper treatment methodologies for the waste streams producing this environmental damage is now a subject of growing concern. A significant number of these waste stream compounds are chemically stable and are thus resistant to environmental degradation. Numerous researchers have investigated the use of ionizing radiation to decompose chlorinated hydrocarbons in diverse matrices and have proposed various free-radical-induced reaction mechanisms. This article is divided into two sections. First, we present data on experimentally measured, radiolytically induced decomposition of hazardous wastes and toxic substances using accelerator-generated bremsstrahlung sources and gamma radiation from cobalt-60. Data are presented on the radiolytically induced reduction in concentration of volatile organic compounds (VOCs) dissolved in water and in air, polychlorinated biphenyls (PCBs) dissolved in oil, high explosives dissolved in groundwater, and chemical weapon surrogates. The results of these studies suggest the potential use of ionizing radiation as a method of hazardous waste treatment. The second section of this article describes the technical aspects of a field-scale radiolytic decomposition site cleanup demonstration using an electron accelerator. A portable, commercially available electron accelerator was set up at the Lawrence Livermore National Laboratory's (LLNL's) Site 300, a Superfund site, where vacuum extraction wells were removing trichloroethylene (TCE) vapor from a ground spill into the unsaturated soil zone. The accelerator was retrofitted into the existing vacuum extraction system such that the extracted TCE-containing vapor passed through the accelerator beam for treatment. The concentration of TCE in the vapor was reduced by an amount dependent on the accelerator beam power. Production of reaction products in the vapor was measured as a function of absorbed dose.     

Literature review: Electrodialytic remediation and potential environmental applications of oil fly ash

Oil fly ash (OFA) contains environmentally toxic heavy metal and substituted polycyclic aromatic hydrocarbons. This review discusses the physical and chemical properties of OFA and presents information from other types of fly ash that can be used as concepts for the remediation and uses of OFA. Electrokinetic remediation is useful to remove some of the heavy metals for broader uses of the fly ash in agriculture, for making construction material, for contaminated wastewater treatment, and also for carbon dioxide sequestration. This review can be useful to develop approaches for the remediation and environmental management of OFA. © 2012 Wiley Periodicals, Inc.     

Noncombustion technologies for remediation of persistent organic pollutants in stockpiles and soil

Persistent organic pollutants (POPs) are a set of chemicals that are toxic, persist in the environment for long periods of time, and biomagnify as they move up through the food chain. Combustion technologies have been the principal technology used to destroy POPs. However, combustion technologies can create polychlorinated dibenzo‐p‐dioxins and polychlorinated dibenzo‐p‐furans, which are human carcinogens. Two organizations, the United Nations Environment Programme (UNEP) and the International HCH and Pesticides Association (IHPA) have developed detailed reports and fact sheets about noncombustion technologies for POP treatment. This article is intended to update and summarize these reports in a concise reader's guide, with links to sources of further information. The updated information was obtained by reviewing various Web sites and documents, and by contacting technology vendors and experts in the field. © 2006 Wiley Periodicals, Inc.     

Literature overview: Microbial metabolism of high molecular weight polycyclic aromatic hydrocarbons

High molecular weight polycyclic aromatic hydrocarbons (HMW PAHs) increase in hydrophobicity with increases in their molecular weight and ring angularity. Microbial strategies to deal with PAH hydrophobicity include biofilm formation, enzyme induction, and biosurfactants, the effect of which is variable on PAH metabolism depending on the surfactant type and concentration, substrate, and microbial strain(s). Aerobic HMW PAH metabolism proceeds via mineralization, partial degradation, and cometabolic transformations. Generally, bacteria and nonlignolytic fungi metabolize PAHs via initial PAH ring oxidation by dioxygenases to form cis‐dihydrodiols, which are transformed to catechol compounds by dehydrogenases and other mono‐ and dioxygenases to substituted catechol and noncatechol compounds, all ortho‐ or metacleaved and further oxidized to simpler compounds. However, lignolytic fungi form quinones and acids to CO₂. This review discusses the pathways for HMW PAH microbial metabolism. © 2008 Wiley Periodicals, Inc.     

Case study: On-site remediation of soil and groundwater for a michigan town's water supply

In 1993 environmental consultants, working in concert with the State of Michigan, discovered groundwater contamination that threatened the drinking water supply of the town of Big Rapids. The contamination originated from leaking underground storage tanks and gasoline lines, which were removed. A pilot study indicated the contaminated area extended to 240′ x 180′ and affected soil as well as groundwater. A remediation plan was designed by and implemented by Continental Remediation Systems, Inc., a Natick, Massachusetts, firm. The remediation plan is ongoing and includes an interceptor trench to stop gasoline from flowing into the creek, as well as air sparging to vent and treat the contaminated soil. It is anticipated that the remediation project will take six months to complete. The chief advantage of on-site remediation is that it avoids the costs and liabilities associated with landfill disposal and no materials need leave the site.     

Reducing salinity and organic contaminants in the Pearl Harbor dredged material using soil amendments and plants

Phytoremediation is an emerging technique that can be used to economically remediate sites contaminated with trace elements and/or man‐made organic contaminants. This technique was used on Pearl Harbor (Oahu, Hawaii) dredged material (PHDM) containing polycyclic aromatic hydrocarbons (PAHs) and some heavy metals. The dredged material was first amended with a high‐calcium soil (Waialua Mollisol) and a biosolids‐based compost at different proportions to yield varying salinity levels. A mixture that yielded an electrical conductivity (EC, a measure of salinity) of the saturated paste extract of 15 to 20 dS/m was identified and used to evaluate the salt tolerance of five plant species. Relative germination and one‐month‐old biomass indicated that common bermuda grass (Cynodon dactylon), seashore paspalum (Paspalum vaginatum), beach pea (Vigna marina), and cow pea (Vigna unguiculata) can produce at least 40 percent of biomass of the control at an EC of approximately 18 dS/m, suggesting the four plants are relatively salt tolerant. In contrast, Desmodium intortum either did not germinate or died within two weeks after germination at the same salinity level. A subsequent greenhouse experiment, using mixtures of the PHDM (0 or 25 percent dry weight), organic amendments (10 percent leucaena green manure or biosolids‐based compost), and a Mollisol (65 or 90 percent dry weight) in 6‐liter pots containing 4 kilograms of material yielded the following results: (1) A combination of transplanted seashore paspalum, seeded bermuda grass, and seeded beach pea was effective in taking up sodium (Na), thereby reducing salinity and making the medium more amenable to diversified microbes and plants, which may be effective PAH degraders; (2) total PAH concentration was reduced by about 30 percent after three months of active plant growth, but degradation of individual PAH members varied significantly, however; (3) leguminous green manure, as a soil amendment, was more effective than compost for use in bio‐ and/or phytoremediations; and (4) soil amendments, when applicable, could supplement living plants in reducing organic contaminants, such as PAHs. © 2002 Wiley Periodicals, Inc.     

火电厂节水技术综述

对火电厂用水、废水的产生情况进行了研究,提出相应的废水处理及再利用对策,并介绍了国内外火电厂的节水技术方案和措施,可为火电厂的节水工作提供借鉴.     

Performance of water cut-off and remediation promotion techniques at coastal waste landfill sites

This paper proposes the construction of steel pipe sheet pile (SPSP) cutoff walls for promoting remediation of water-soluble toxic substances and containment of water-soluble toxic substances at landfill sites in order to maintain and ensure the environmental safety of waste landfill sites over time. It investigates environmental safety at coastal waste landfill sites by applying water cut-off and remediation promotion techniques to the joint sections of SPSP water cut-off walls that provide shore protection for waste landfills. Results from the research herein show that the construction of SPSP water cut-off walls with features such as the containment of water-soluble toxic substances and remediation promotion is possible by applying water cut-off and remediation techniques to H–H joints, which are structural joint components of SPSP walls. In addition, they show that the performance of remediation in H–H joints can be controlled by adjusting the water cut-off efficiency of the H–H joint flange.     

Citrus essential oils and their influence on the anaerobic digestion process: An overview

Citrus waste accounts for more than half of the whole fruit when processed for juice extraction. Among valorisation possibilities, anaerobic digestion for methane generation appears to be the most technically feasible and environmentally friendly alternative. However, citrus essential oils can inhibit this biological process. In this paper, the characteristics of citrus essential oils, as well as the mechanisms of their antimicrobial effects and potential adaptation mechanisms are reviewed. Previous studies of anaerobic digestion of citrus waste under different conditions are presented; however, some controversy exists regarding the limiting dosage of limonene for a stable process (24–192 mg of citrus essential oil per liter of digester and day). Successful strategies to avoid process inhibition by citrus essential oils are based either on recovery or removal of the limonene, by extraction or fungal pre-treatment respectively.     

Translating a remediation technology into the required air,water, and rcra permits

Because remediation techniques and technologies are themselves generally viewed as contaminant source by hazardous waste laws and regulations, permits are required to use them, even if it is only to contain or remove a site's principal contaminants. Referring to such major environmental laws as the Clean Air Act, the Clean Water Act, RCRA, TSCA, and CERCLA, this article outlines the steps needed to translate cleanup projects into the appropriate permits.     

Superfund site remediation by landfilling—overview of landfill design,operation, closure,and postclosure issues

This article discusses the appropriateness of using landfills as part of remediating hazardous chemical and Superfund sites, with particular emphasis on providing for true long‐term public health and environmental protection from the wastes and contaminated soils that are placed in the landfills. On‐site landfilling or capping of existing wastes is typically the least expensive approach for gaining some remediation of existing hazardous chemical/Superfund sites. The issues of the deficiencies in US EPA and state landfilling approaches discussed herein are also applicable to the landfilling of municipal and industrial solid “nonhazardous” wastes. These deficiencies were presented in part as “Problems with Landfills for Superfund Site Remediation” at the US EPA National Superfund Technical Assistance Grant Workshop held in Albuquerque, New Mexico, in February 2003. They are based on the author's experience in investigating the properties of landfill liners and the characteristics of today's landfills, relative to their ability to prevent groundwater pollution and to cause other environmental impacts. Discussed are issues related to both solid and hazardous waste landfills and approaches for improving the ability of landfills to contain wastes and monitor for leachate escape from the landfill for as long as the wastes in the landfill will be a threat. © 2004 Wiley Periodicals, Inc.     

Adsorbable organic halides (AOX), AOX formation potential, and PCDDs/DFs in landfill leachate and their removal in water treatment processes

Adsorbable organic halides (AOX) and AOX formation potential (AOXFP) were investigated in 46 landfill lea-chates as potentially toxic parameters. AOX in landfill leachate was within the range <10–2200 μg Cl/l, and AOXFP was within 51–15 000 μg Cl/l. AOX and AOXFP correlated with chemical oxygen demand (COD). AOX discharge from closed landfills was generally lower than that from operating landfills. The molar ratio of AOXFP/total organic carbon (TOC) suggested that organic compounds in a leachate have a double bond every 15–190 carbons under the supposition that one chlorine would add to one double bond. The five landfills discharging high-level AOXFP (>4000 μg Cl/l) were all landfills where sludge had been dumped. The removal efficiencies of three parameters through leachate treatment processes were as follows: polychlorinated dibenzo-dioxins/dibenzo-furans (PCDDs/DFs) > TOC > AOX. PCDDs/DFs were substantially removed at p.p.t. levels, while AOX was hardly removed at relatively low levels. Received: February 14, 2000 / Accepted: January 9, 2001     

Nanotechnology and groundwater remediation: A step forward in technology understanding

Nanotechnology application to contaminated site remediation, and especially the use of nanoscale zero‐valent iron particles to treat volatile organic compound (VOC)‐impacted groundwater, is now recognized as a promising solution for cost‐effective in situ treatment. Results obtained during numerous pilot tests undertaken by Golder Associates between 2003 and 2005 in North America (United States and Canada) and Europe have been used to present a synthetic cross‐comparison of technology dynamics. The importance of a comprehensive understanding of the site‐specific geological, hydrogeological, and geochemical conditions, the selection of appropriate nanoscale particles, the importance of monitoring geochemical parameters during technology application, and the potential of nanoparticle impact on microbial activity are discussed in this article. The variable technology dynamics obtained during six pilot tests (selected among numerous other tests) are then presented and discussed. © 2006 Wiley Periodicals, Inc.     

Biogas from the organic fraction of municipal solid waste: Dealing with contaminants for a solid oxide fuel cell energy generator

The present work investigates electricity production using a high efficiency electrochemical generator that employs as fuel a biogas from the dry anaerobic digestion of the organic fraction of municipal solid waste (OFMSW).The as-produced biogas contains several contaminants (sulfur, halogen, organic silicon and aromatic compounds) that can be harmful for the fuel cell: these were monitored via an innovative mass spectrometry technique that enables for in-line and real-time quantification.A cleaning trap with activated carbons for the removal of sulfur and other VOCs contained in the biogas was also tested and monitored by observing the different breakthrough times of studied contaminants.The electrochemical generator was a commercial Ni anode-supported planar Solid Oxide Fuel Cell (SOFC), tested for more than 300 h with a simulated biogas mixture (CH₄ 60 vol.%, CO₂ 40 vol.%), directly fed to the anode electrode. Air was added to promote the direct internal conversion of CH₄ to H₂ and CO via partial oxidation (POx).The initial breakthrough of H₂S from the cleaning section was also simulated and tested by adding ～1 ppm(v) of sulfur in the anode feed; a full recovery of the fuel cell performance after 24 h of sulfur exposure (～1 ppm(v)) was observed upon its removal, indicating the reliable time of anode exposure to sulfur in case of exhausted guard bed.