Successful unsaturated zone treatment of PCE with sodium permanganate

In situ chemical oxidation (ISCO) with permanganate has been widely used for soil and groundwater treatment in the saturated zone. Due to the challenges associated with achieving effective distribution and retention in the unsaturated zone, there is a great interest in developing alternative injection technologies that increase the success of vadose‐zone treatment. The subject site is an active dry cleaner located in Topeka, Kansas. A relatively small area of residual contamination adjacent to the active facility building has been identified as the source of a large sitewide groundwater contamination plume with off‐site receptors. The Kansas Department of Health and Environment (KDHE) currently manages site remedial efforts and chose to pilot‐test ISCO with permanganate for the reduction of perchloroethene (PCE) soil concentrations within the source area. KDHE subsequently contracted Burns & McDonnell to design and implement an ISCO pilot test. A treatability study was performed by Carus Corporation to determine permanganate‐soil‐oxidant‐demand (PSOD) and the required oxidant dosing for the site. The pilot‐test design included an ISCO injection approach that consisted of injecting aqueous sodium permanganate using direct‐push technology with a sealed borehole. During the pilot test, approximately 12,500 pounds of sodium permanganate were injected at a concentration of approximately 3 percent (by weight) using the methods described above. Confirmation soil sampling conducted after the injection event indicated PCE reductions ranging from approximately 79 to more than 99 percent. A follow‐up treatment, consisting of the injection of an additional 6,200 pounds of sodium permanganate, was implemented to address residual soil impacts remaining in the soil source zone. Confirmation soil sampling conducted after the treatment indicated a PCE reduction of greater than 90 percent at the most heavily impacted sample location and additional reductions in four of the six samples collected. © 2009 Wiley Periodicals, Inc.     

Design considerations of constructed wetlands to reduce landfill leachate contamination in tropical regions

In tropical regions, landfill leachate contamination at municipal solid waste disposal sites is a critical issue because of the large volume of highly contaminated leachate formed during the rainy season. We evaluated the efficacy of constructed wetlands (CWs) with the ability to reduce the water volume and pollutant levels to reduce leachate contamination compared to the most commonly used treatment system, stabilization ponds, based on parameters obtained in a field experiment in Thailand. The simulation indicated that CWs had a higher potential to reduce the water volume than stabilization ponds over the course of a year. Scenario evaluations under varying initial water depths, system depths, and area sizes indicated that the CWs could reduce the treatment area to prevent overflow and leachate pollution. In addition, the CWs were estimated to reduce the leachate amount and pollution by 83–100% and 92–99%, respectively. When there is limited land available, deeper CWs can be used to sustainably prevent contamination from leachate overflow. Effectively designed CW systems may be valuable for both reducing the required area and the contamination; therefore, CWs are a promising option for sustainable landfill leachate treatment systems in developing tropical regions.     

Pollutant source identification and allocation: Advances in hydrocarbon fingerprinting

Often liability for environmental damage and cleanup of contaminated sites is made difficult, especially with chemically complex environments containing different pollutants, by the inability to differentiate potential sources (or “owners”) of pollutants from each other. As a result, unnecessary costs may be associated with having to assume financial responsibility for alleged contamination of a site. This article reviews the advances in chemical fingerprinting as a tool in identifying and differentiating sources of hydrocarbon pollutants in chemically complex environments. Appropriate hydrocarbon target analytes and required analytical methods for hydrocarbon fingerprinting are discussed, and new interpretative tools are presented that may be applied to contaminated soil, sediment, and groundwater environmental situations. With these analytical and interpretative techniques, an appropriate allocation of chemical contamination and costs at a site can be made.     

Evaluating PFAS cross contamination issues

Avoiding cross contamination from per‐ and polyfluoroalkyl substances (PFAS) that may occur during sampling of environmental media is the key to ensure reliable analytical results during a PFAS sampling program. Due to the ubiquitous nature of PFAS in commonly used sampling materials and personal protective equipment, mitigating the risk of cross contamination is a challenge that requires a conservative approach when planning and executing a PFAS sampling program. This article describes a conservative approach to PFAS sampling and includes a case study that evaluated three insect repellent products to determine their suitability for use during PFAS investigation. The three products were verified to be PFAS‐free for the 17 PFAS included in the analysis and, therefore, these products are suitable for use during PFAS sampling activities without concern for cross contamination.     

Net impact of remediation

Following years of progress in designing and executing cleanups of contaminants at waste sites, the U.S. Air Force, state regulatory groups, and others are crafting methods to evaluate broader considerations of risk in remedial decisions. Integrating worker and climate risks into remediation efforts may confer significant benefits, but challenges exist to identifying, assessing, and accounting for them in the remedial process. For sites where future risk posed by contamination far exceeds the risk posed to workers who may be exposed to the contaminants during the remedial process, limiting the range of decision inputs to those presented by the site conditions made sense and provided a net benefit to human health and the environment. There are other sites, however, where future risk posed by the in situ contamination are at levels comparable to the real risks posed to workers, ecology, and even emerging concerns about climate change. For these sites, a net risk reduction cannot be assumed to be a result of remedial action, challenging the remedial community to develop new approaches to ensure positive results. © 2009 Wiley Periodicals, Inc.     

Per‐ and polyfluoroalkyl substances in environmental sampling products: Fact or fiction?

Can per‐ and polyfluoroalkyl substances (PFAS) be transferred from the common field and other commercial products during sampling? Special handling and care are always advised when collecting samples for PFAS analysis to avoid sample contamination. The potential presence of PFAS in common consumer products and in equipment typically used to collect environmental samples, coupled with the need for very low reporting limits heightens this concern. In this paper, the authors investigate what the potential for cross‐contamination is from a number of commonly used products, with the emphasis on evaluating what the possible worst‐case scenario for cross‐contamination could be. Polytetrafluoroethylene (PTFE), low‐density polyethylene (LDPE), and high‐density polyethylene (HDPE) tubing, pump bladders, and other materials are evaluated along with associated products such as aluminum foil and plastic storage bags. In the experimental design of this study, the products themselves are not analyzed directly for PFAS. Rather, a series of experiments are performed utilizing a leaching procedure to evaluate the potential for cross‐contamination and false‐positive environmental sampling results. This study was performed in a series of experimental batches over the course of a 1‐year period. Analytical results are presented along with experimental observations and recommendations.     

石油开采行业土壤污染防治对策与建议

在文献和实地调研的基础上,分析了石油开采行业生产工艺及产排污情况,识别了油井、注水井、输油管道、联合站等主要工艺节点的土壤污染风险,总结了目前行业处理废水和危险废物的主要方法,指出了行业在废弃钻井液处理、地下输油管道泄漏后期处置及突发环境事件应急预案中土壤污染防治等方面存在的问题,并提出了相应的对策和建议。     

Acetone and 2‐butanone creation associated with biological and chemical remediation of environmental contamination

Remediating environmental contamination by either biological or chemical methods typically results in the generation of temporary chemical intermediates as part of the process. These intermediate compounds may be related to either contaminant degradation pathways or reactions generated from the amendment itself. This article summarizes previously researched pathways and representative case studies discussing the authors' experience in generating relatively high concentrations of acetone and 2‐butanone (also referred to as methyl ethyl ketone [MEK]) during both biological and chemical treatments. Experience shows that even relatively high concentrations of acetone and MEK intermediates are quickly attenuated and prove not to be a hazard outside of the treatment area. © 2011 Wiley Periodicals, Inc.     

Uptake and Metabolism of TNT and GTN by Plants Expressing Bacterial Pentaerythritol Tetranitrate Reductase

The manufacture and improper disposal of explosives has resulted in a significant amount of land requiring remediation. The compound 2,4,6-trinitrotoluene (TNT) is the most persistent and toxic of the explosive pollutants with current treatment methods being energy intensive and costly. Bacterial enzymes such as pentaerythritol tetranitrate reductase (PETNR) from Enterobacter cloacae PB2 have been found to have activity against TNT; however, microbes often lack the biomassnecessary for remediation applications. The PETNRgene (onr1) was transformed into tobacco plants in an attempt to combine the metabolic diversity of microbes with the sequestering properties of plants. The resulting transgenic plants were shown to have enhanced tolerance to TNT during germination and as seedlings. Phytoremediation applications with these plants may provide an alternative treatment of TNT contamination.     

Screening method for locating groundwater monitoring wells

The traditional approach to characterizing the extent of groundwater contamination is often phased over a period of several years. A screening method has been developed that allows the investigation process to be reduced to a single phase. Existing data are used to develop a preliminary estimate of the extent of contamination, which is refined by the screening method using groundwater data collected and analyzed in the field. The screening method is applicable at sites with volatile organic compound contamination. Groundwater samples are collected using direct push or drill rig assisted methods, and the groundwater headspace gas is analyzed for the contaminant of interest. The refined estimate is used to locate all of the groundwater monitoring wells necessary to finalize the estimate of the extent of contamination. Therefore, only one investigation phase is required, and time and cost savings are realized with respect to the traditional multiphase approach. The screening method was successfully applied at a CERCLA site in Nebraska with two distinct plumes of TCE-contaminated groundwater. The Nebraska remedial investigation was completed approximately 18 months earlier than the estimated completion of a comparable phased investigation, with a corresponding cost reduction estimated at approximately 10 percent. If data from the screening method were used instead of data from monitoring wells, the estimated cost savings would be over 50 percent. Additional applications and evaluations may lead to industry and regulatory acceptance of the method as a primary characterization tool.     

Contamination of the environment by the current disposal methods of mercury-containing lamps in the state of Minas Gerais, Brazil.

This survey describes the degree of environmental contamination resulting from the current disposal methods of mercury-containing lamps. The territory studied for this purpose is the federal state of Minas Gerais, one of the most populated areas in the Brazilian federation of states. The results of this survey derive in part from answers received to a questionnaire mailed out to industrial firms, commercial business enterprises, hospitals and departments of public work. The sampling technique used was a nonprobabilistic (purposive sampling). Three types of disposal were found to prevail: (1) as an addition to corporate waste disposal (garbage), (2) recycling and (3) disposal by other methods. Overall, our study shows that the majority of mercury lamps are being disposed in the metropolitan area of Belo Horizonte, primarily by the public sector, followed by industrial, commercial and hospital sectors. Although recycling constitutes a relatively high fraction of the disposal methods, we find Federal regulations in Brazil regarding the disposal of hazardous, mercury-containing lamps to be far behind the state of technological achievement. This gap has permitted the adoption of disposal measures that are obsolete, incorrect, and a primary cause for the extensive contamination of the ecosystems with harmful effects to human health.     

Recent applications of phytoremediation technologies

Although the application of microbe biotechnology has been successful with petroleum-based constituents, microbial digestion has met with limited success for widespread residual organic and metal pollutants located above the potentiometric surface. Vegetation-based remediation, on the other hand, shows potential for accumulating, immobilizing, and transforming low levels of persistent contamination from the subsurface. Agricultural bioremediation, called geobotany or phytoremediation, relies on the remediating abilities of contaminant-accumulating plants to remove contamination from soil or groundwater. In natural ecosystems, plants act to filter and metabolize substances generated by nature. Phytoremediation affirmatively applies this process to help clean up contamination created by artificial means. Plants have proven effective at remediating areas contaminated with organic chemical wastes such as petroleum products, solvents, wood preservatives, pesticides, and metals. Phytoremediation is not the best technology for every site but has shown success with lead, cadmium, zinc, and radionuclides. The phytoremediation process takes much longer than conventional methods to clean a site and is dependent upon the type and degree of contamination. Concentrations must be within a narrow range of tolerable levels and the presence of the contamination must be at the appropriate depth. Nevertheless, phytoremediation offers an effective alternative to conventional, engineered remedial plans that usually involve costly activities like excavation, treatment, and disposal of soil or pump-and-treat technologies for groundwater. Phytoremediation also seems to be a promising new technology for the treatment of stormwater, industrial wastewater, and sewage. The relative low costs of capital for start-up together with negligible operations and maintenance costs provide a strong incentive for further investigation and development of phytoremediation projects.     

重金属废水处理与资源化利用现状

重金属废水的排放是重金属污染的重要源头之一。介绍了目前国内外用于处理不同重坌属废水的方法,以及重金属废水资源化可采用的多种工艺。在重金属废水资源化技术中,膜分离技术起着十分重要的作用。     

Adaptive sampling and analysis programs for contaminated soils

Adaptive sampling and analysis programs (ASAPs) provide a cost-effective alternative to traditional sampling program designs. ASAPs are based on field analytical methods for rapid sample turnaround and field-based decision support for guiding the progress of the sampling program. One common objective of ASAPs is to delineate contamination present in soils, either to support feasibility studies or remedial action designs. An ASAP based on portable gas chromatograph/ mass spectrograph (GC/MS) technologies developed at Tufts University combined with decision support tools created at Argonne National Laboratory was used to delineate explosives contamination in soils at Joliet Army Ammunition Plant, Joliet, Illinois. Tufts' GC/MS technologies provided contaminant-specific identification and quantification with rapid sample turnaround and high sample throughput. Argonne's decision support tools estimated contamination extent, determined the uncertainty associated with those estimates, and indicated where sampling should continue to minimize uncertainty. In the case of Joliet, per sample analytical costs were reduced by 75 percent as compared to the cost of off-site laboratory analyses for explosives. The use of an ASAP resulted in a much more accurate identification and delineation of contaminated areas than a traditional sampling program would have with the same number of samples collected on a regular grid. While targeting explosives contamination in soils at Joliet, the ASAP technologies used in this demonstration have much broader application.     

Organic Nitrogen in Precipitation Across the United Kingdom

The concentration of water-soluble organic nitrogen (WSON) in precipitation has been measured at seven sites across the United Kingdom, over a period of 1–2 years, using protocols developed in a pilot study. Samples were collected over 1–2 weeks in continuously open funnels made of stainless steel, draining to a glass bottle, and were preserved during and after collection by the addition of thymol. After chemical analysis, samples were excluded from the long-term average if they showed signs of contamination (significant concentrations of K⁺ or PO₄ ^3–). Two methods of measuring total dissolved N were used, persulphate oxidation and high-temperature chemiluminescence. The latter generally gave the larger values, and has been used to asses the organic component of dissolved N. The long-term data set confirms the original results from the pilot study - organic N contributes between 24 and 40% to the total annual wet deposition of dissolved N across the United Kingdom. The fraction of WSON was greatest at western sites, and was strongly correlated with ammonium concentrations. However, the seasonal pattern across all sites showed a late spring maximum for ammonium and nitrate, but a late summer maximum for WSON. The magnitude of the contribution of WSON to wet-deposited N has implications for the setting and assessment of critical loads for N deposition.     

Remediation of MTBE-Contaminated Water and Soil

As the number of leaking underground fuel tank sites with methyl tertiary butyl ehter (MTBE) contamination continues to grow, there is a need to develop cost-effective solutions for treatment of soil and water contamination. MTBE poses special challenges because of its physicochemical properties, in particular high solubility and low Henry's constant, low affinity for sorption, and very slow rate of microbial degradation. Advanced oxidation processes tend to generate undesirable by-products. Based on laboratory studies with hollow fiber membranes (HFM), a field-scale unit was constructed and tested at a number of sites, to determine the effectiveness of this technology in dealing with MTBE contamination. In addition, to treat the soil contamination, the HFM unit was coupled with a Spray Aeration Vapor Extraction (SAVE) unit, which is based on an internal combustion engine. The engine provides the means to treat soil vapors, as well as organic vapors from the spray aeration and HFM units. The overall treatment objectives of 5μg/l for MTBE and 1 μg/l for benzene were achieved with a treatment train consisting of an ion exchange unit, a spray aeration system, a hollow fiber membrane module and two granular activated carbon (GAC) units, for flowrates ranging from 3.8 to 30 l/min (1 to 8 gal/min). The ion exchange unit sewed to reduce water hardness and avoid scaling in the subsequent treatment units, extending the run-time of the entire system. Overall removal efficiencies for the spray aeration system and hollow fiber membrane module ranged from 85 to over 99 percent. High removal efficiencies (> 97%) were obtained at elevated water temperatures (54°C) or lower flowrates (up to 11 l/min). The GAC units were used only to polish the effluent and meet the discharge requirements. Soil, water, and gas phases are treated with this system. Cost estimates are provided for similar treatment processes, for water flowrates up to 38 l/min (10 gal/min). © 1999 John Wiley & Sons, Inc.     

Characterization of municipal solid waste from the main landfills of Havana city

The city of Havana, the political, administrative and cultural centre of Cuba, is also the centre of many of the economic activities of the nation: industries, services, scientific research and tourism. All of these activities contribute to the generation of municipal solid waste (MSW), which also impact other Cuban cities. Inadequate handling of waste and the lack of appropriate and efficient solutions for its final disposal and treatment increase the risk and possibility of contamination. The main difficulty in the development of a system of management of MSW lies in the lack of knowledge of the chemical composition of the waste that is generated in the country as a whole, and especially in Havana, where solid waste management decisions are made. The present study characterizes MSW in Havana city during 2004. The Calle 100, Guanabacoa and Ocho Vías landfills were selected for physical-chemical characterization of MSW, as they are the three biggest landfills in the city. A total of 16 indicators were measured, and weather conditions were recorded. As a result, the necessary information regarding the physical-chemical composition of the MSW became available for the first time in Cuba. The information is essential for making decisions regarding the management of waste and constitutes a valuable contribution to the Study on Integrated Management Plan of MSW in Havana.     

Removal,Handling, and Thermal Desorption Treatment Techniques for Manufactured Gas Plant Wastes

Due to the nature of contamination typically found at former MGP (manufactured gas plant) sites, excavation and thermal desorption of MGP wastes has proven to be an effective method for the remediation of MGP‐contaminated soil. The use of on‐site thermal desorption enables MGP sites to be quickly remediated at a low cost. Tar pits, holders, and other underground storage structures typically contain coal tar residuals and waste from former operations, and the areas around these structures are often significantly contaminated. Thus, excavation techniques, odor and vapor management, and material preparation for the treatment method are important factors to consider when developing a site remediation strategy. This article reviews typical excavation and handling methods associated with the remediation of former MGP sites and discusses the treatment of MGP wastes using on‐site thermal desorption technology. © 2001 John Wiley & Sons, Inc.     

Borehole‐scale testing of matrix diffusion for contaminated‐rock aquifers

A new method was developed to assess the effect of matrix diffusion on contaminant transport and remediation of groundwater in fractured rock. This method utilizes monitoring wells constructed of open boreholes in the fractured rock to conduct backward diffusion experiments on chlorinated volatile organic compounds (CVOCs) in groundwater. The experiments are performed on relatively unfractured zones (called test zones) of the open boreholes over short intervals (approximately 1 meter) by physical isolation using straddle packers. The test zones were identified with a combination of borehole geophysical logging and chemical profiling of CVOCs with passive samplers in the open boreholes. To confirm the test zones are within inactive flow zones, they are subjected to a series of hydraulic tests. Afterward, the test zones are air sparged with argon to volatilize the CVOCs from aqueous to air phase. Backward diffusion is then measured by periodic passive‐sampling of water in the test zone to identify rebound. The passive (nonhydraulically stressed) sampling negates the need to extract water and potentially dewater the test zone. The authors also monitor active flowing zones of the borehole to assess trends in concentrations in other parts of the fractured rock by purge and passive sampling methods. The testing was performed at the former Pease Air Force Base (PAFB) in Portsmouth, New Hampshire. Bedrock at the former PAFB consists of fractured metasedimentary rocks where the authors investigated back diffusion of cis‐1,2‐dichloroethylene (cis‐1,2‐DCE), a CVOC. Postsparging concentrations of cis‐1,2‐DCE showed initial rebounding followed by declines, excluding an episodic spike in concentrations from a groundwater recharge event. The authors theorize that there are three processes that controlled concentration responses in the test zones postsparging. First, the limited back diffusion of CVOCs from a halo or thin zone of rock around the borehole contributes to the initial rebounding. Second, aerobic degradation of cis‐1,2‐DCE occurred causing declines in concentrations in the test zone. Third, microflow from microfractures contributed to the episodic spike in concentrations following the groundwater recharge event. In active flow zones, the latter two processes are not measurable due to equilibration from groundwater transport between the borehole and active flowing fractures.