The use of enhanced bioremediation at the Savannah River Site to remediate pesticides and PCBs

Enhanced bioremediation is quickly developing into an economical and viable technology for the remediation of contaminated soils. Until recently, chlorinated organic compounds have proven difficult to bioremediate. Environmentally recalcitrant compounds, such as polychlorinated biphenyls (PCBs) and persistent organic pesticides (POPs) such as dichlorodiphenyl trichloroethane (DDT) have shown to be especially arduous to bioremediate. Recent advances in field‐scale bioremedial applications have indicated that biodegradation of these compounds may be possible. Engineers and scientists at the Savannah River Site (SRS), a major DOE installation near Aiken, South Carolina, are using enhanced bioremediation to remediate soils contaminated with pesticides (DDT and its metabolites, heptachlor epoxide, dieldrin, and endrin) and PCBs. This article reviews the ongoing remediation occurring at the Chemicals, Metals, and Pesticides (CMP) Pits using windrow turners to facilitate microbial degradation of certain pesticides and PCBs. © 2003 Wiley Periodicals, Inc.     

Remediation of PCB‐Contaminated Soil Using Extraction and Destruction: Bench‐Scale Test

Polychlorinated biphenyls (PCBs) are a persistent environmental issue worldwide. This study summarizes the results obtained from a bench‐scale test of remediating PCB‐impacted soil. The research aimed to evaluate the effectiveness of extracting the PCB Aroclor 1260 from soil, transferring it to a liquid matrix, and then treating the PCB‐containing liquid using an Activated Metal Treatment System, a technology developed by NASA based on zero valent magnesium (ZVMg). The soil was from a former electrical plant area impacted by PCBs. The initial concentration of untreated soil contained an average of 4.7 ± 0.15 mg/kg of Aroclor 1260. The results showed that the mass transfer phenomena is possible using ethanol as a liquid matrix, reaching transfer results up to 93 percent. The ZVMg enabled the destruction of the Aroclor 1260, which reached 20 percent without any buildup of undesirable by‐products, such as less chlorinated PCBs.  ©2016 Wiley Periodicals, Inc.     

Removal of polychlorinated biphenyls from capacitors and pressure-sensitive paper by vacuum thermal recycling

This paper describes a new vacuum thermal recycling (VTR) method for treating discarded polychlorinated biphenyls (PCB)-contaminated capacitors and pressure-sensitive paper. Based on results demonstrating an exceptionally high PCB separation efficiency and recovery ratio from capacitors containing high-concentration PCBs, i.e. > 99.9%, respectively, the presented VTR method is verified to effectively remove PCBs. In addition, associated safety aspects of the employed procedure were confirmed.     

Effects of cosolvency in the fate and transport of PCBs in soil

Under the purview of EPA's Remedial Engineering Management (REM III) Superfund contract, a CERCLA RI/FS was performed at the Pinettes Salvage Yard site located in Washburn, Maine (EPA Region I). The purpose of the RI/FS was to fully characterize the nature, extent, and fate and transport of PCB contamination resulting from an alleged surface spill of transformer dielectric fluid containing Arochlor 1260 (a polychlorinated biphenyl) and various volatile and semivolatile organic constituents. The RI/FS was performed subsequent to both an immediate removal action (IRA) and a deletion remedial investigation (DRI) performed by EPA contractors. Results of both efforts indicated that the site was unsuitable for deletion from the National Priorities List (NPL) because the site soils contained elevated levels of PCBs. This article presents a case history of the extensive field investigations performed to characterize the contaminant source and evaluate the fate and transport of PCBs in site soils. These investigations included on-site mobile laboratory gas chromatograph (GC) analytical techniques for PCBs and targeted volatile and semivolatile organic compounds; confirmatory Contact Laboratory Program (CLP) laboratory analyses of soils, sediments, surface water, and groundwater samples; statistical analyses and correlation of field mobile laboratory GC data with CLP laboratory analytical results; and an evaluation of the potential effects of cosolvency in the fate and transport of PCBs in subsurface soils.     

PCBs,PBDEs and dioxin-related compounds in floor dust from an informal end-of-life vehicle recycling site in northern Vietnam: contamination levels and implications for human exposure

Floor dusts from Vietnamese end-of-life vehicle (ELV)-processing households were investigated to elucidate the contamination levels and exposure risk of polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and dioxin-related compounds (DRCs). The concentrations were in order of PBDEs (260–11,000, median 280 ng/g overall) > PCBs (19–2200, median 140 ng/g) > dioxin-like PCBs (8.8–450, median 22 ng/g) ? polybrominated dibenzo-p-dioxin/dibenzofurans (PBDD/Fs, 2000–28,000, median 8500 pg/g) > polychlorinated dibenzo-p-dioxin/dibenzofurans (PCDD/Fs, 440–4100, median 1800 pg/g) > MoBPCDD/Fs (1.9–1200, median 250 pg/g). Concentrations of PCBs and DRCs were higher than those reported for Vietnamese urban houses, indicating ELV processing as a significant source of these contaminants. Higher concentrations of PCBs relative to PBDEs suggest the abundance of old electrical capacitors/transformers in ELVs. The PBDD/F and PCDD/F profiles were indicative of DecaBDE-containing materials and combustion sources, respectively. PBDFs, PCDFs and DL-PCBs were the most important dioxin-like toxic equivalent (TEQ) contributors. The estimated PCB and TEQ intake doses from dust ingestion approached or exceeded the reference doses for children living in some ELV-processing households, indicating potential health risk. More comprehensive risk assessment of the exposure to PCBs and DRCs is required for residents of informal ELV recycling sites.     

Safety management by use of laser mass spectrometry of polychlorinated biphenyls (PCBs) in the processed gas and work environment of a PCB disposal plant

This study demonstrates the applicability of laser mass spectrometry for safety management of the processed gas and the work environment in a polychlorinated biphenyl (PCB) disposal plant. By utilization of laser ionization/ion trapping storage/time-of-flight mass spectrometry (LI-IT-TOFMS), we analyzed gaseous PCBs from scrap capacitors with on-line detection. It was confirmed that few contaminants were detected in the spectrum. By the effect of laser-induced selective ionization, it was considered that there was little interference with the mass range of PCBs. The accuracy of LI-IT-TOFMS when analyzing environmental gas was almost the same as that for the PCB standard gas. It was possible to perform on-line analysis of the work environment for over 2000 h (120 000 data points). LI-IT-TOFMS was thus shown to be a very useful method for ensuring the safety of the work environment in disposal plants for PCBs.     

Assessing the Phytoremediation Potential of Tall Fescue and Sericea Lespedeza for Organic Contaminants in Soil

The phytoremediation potential of using tall fescue (Festuca arundinacea Schreb.) grass and sericea lespedeza (Lespedeza cuneata [Dum. ‐Cours.]) legume species was assessed using three different groups of organic contaminants in soil. One hundred parts per million (ppm) each of a nitroaromatic compound (TNT), a polycyclic aromatic hydrocarbon (Pyrene), and a polychlorinated biphenyl (Aroclor 1248) were used to contaminate the soils. The experiments were conducted using soils with high and low organic‐matter content. The results indicate that recoveries of Pyrene and TNT were very low in all treatments in soil with high organic‐matter content (6.3 percent) compared with recoveries in soil with low organic‐matter content (2.6 percent). In contrast, recoveries of PCB from soil were not dependent on the soil's organic‐matter content. Planting both the legume and grass species had significant effect on the transformations of TNT and PCB in the soil with low organic‐matter content and did not affect the fate of Pyrene in both soils. The amount of TNT transformed in the four months of plant growth was 63 percent in the tall fescue and 46 percent in the sericea‐planted soils, compared with only a 15 percent unaccounted loss in the unplanted control soils. Furthermore, the grass species, with its massive root system, was significantly better at causing TNT dissipation compared with the legume species, which has less root vegetative mass. The plant biomass, particularly the shoot weight of the tall fescue grass, was significantly increased as a result of TNT treatment. Tall fescue and sericea biomass did not appear to have any significant effect on Pyrene transformation. Planting sericea provided a significantly high level of PCB transformation in soils with either high or low amounts of organic matter. Tall fescue did not appear to have any significant effect on PCB transformation. © 2002 Wiley Periodicals, Inc.     

Japan’s waste management policies for dioxins and polychlorinated biphenyls

We summarize the measures taken by the Japanese government to prevent the emission of dioxins and polychlorinated biphenyls (PCBs) into the environment. Because incineration is the main method of waste management in Japan, reducing the amount of dioxins emitted from waste incinerators is an essential aspect of proper waste treatment. Intensive measures to prevent the formation of dioxins at the source have been implemented, with a focus on waste treatment methods and improving comprehensive management. The efforts have been very successful, with a 95% reduction in the amount of dioxins emitted between 1997 and 2003. The toxicity of PCBs has been monitored with keen interest since the Yusho incident. Unfortunately, treatment facilities for PCB wastes were not built until long after PCBs had been removed from use, and PCB wastes remained in storage in an untreated state. The Japanese government has promoted the construction of facilities for treating PCB wastes, and five such facilities have commenced operations. To more completely eradicate dioxins, a future challenge will be to reduce the amount of PCB-derived dioxins, which are persistent in the environment and have a long exposure pathway from the environment media to the organism and the human body.     

Cleanup levels for pcbs and their combustion products at an industrial facility

In 1991, a fire occurred at a foundry in western Pennsylvania. The fire started in capacitors that contained polychlorinated biphenyls (PCBs) and subsequent sampling has indicated that PCBs and products of their incomplete combustion, the polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), were released as a result of the fire. This article develops and provides justification for site-specific cleanup levels for the PCBs, PCDDs, and PCDFs accidentally released into this industrial facility during the fire. Cleanup levels were calculated using standard risk assessment approaches and assumptions, and these riskbased values were compared with cleanup criteria used for other sites. Final criteria were established based on this comparison and a consideration of such site-specific factors as migration potential, industrial use patterns, and the small mass of material present.     

Method development and implementation for co-planar polychlorinated biphenyls (PCBs)

The Emission Measurement Center (EMC) in the Environmental Protection Agency's Office of Air Quality Planning and Standards was directed to conduct an emissions test program at a sewage sludge incinerator in support of a Maximum Achievable Control Technology (MACT) standard. One pollutant category of concern at these facilities was polychlorinated biphenyls, or PCBs. An objective of the test program was to measure co-planar PCBs in the incinerator emissions, the sewage sludge introduced to the incinerator, and the scrubber water effluent used in controlling the incinerator emissions. Co-planar PCB congeners are those having four or more chlorine atoms with only a few substitutions in the ortho positions, i.e. positions designated 2, 2', 6, and 6'. Thirteen PCB compounds are sometimes referred to as the "WHO PCBs," because the World Health Organization (WHO) has derived toxic equivalency factors for these congeners. Studies have shown that these dioxin-like compounds can react with the aryl hydrocarbon receptor. This same reaction is believed to initiate adverse health effects for dioxin and furan congeners. In order to conduct the co-planer PCB testing, the EMC had to develop analytical methods that could measure the 13 co-planar PCBs. The purpose of the test program was to develop, evaluate, and implement analytical test methods capable of measuring co-planar PCBs in three matrices: incinerator stack gases, sewage sludge, and scrubber water effluents. The paper summarizes the initial development work that was performed in preparation of analytical test protocols that could measure co-planar PCBs in air, water, and sludge matrices. Following the method development, a MACT emissions test program was conducted at a sewage sludge facility in July 1999 and these data are also summarized in the paper.     

Thermal desorption of PCB-contaminated waste at the waukegan harbor superfund site

In June 1992, SoilTech ATP Systems, Inc., completed the soil treatment phase of the Waukegan Harbor Superfund Project in Waukegan, Illinois, after approximately five months of operation. SoilTech successfully treated 12,700 tons of sediment contaminated with polychlorinated hiphenyls (PCBs) using a transportable SoilTech anaerobic thermal processor (ATP) system nominally rated at ten tons per hour throughput capacity. The SoilTech ATP technology anaerobically desorbs contaminants such as PCBs from solids and sludges at temperatures over 1,000° F. Principal products of the process are clean, treated solids and an oil condensate containing the hydrocarbon contaminants. At the Waukegan Harbor Superfund site, PCB concentrations in the sediments excavated and dredged from a ditch, lagoon, and harbor slip averaged 10,400 parts per million (ppm) (1.04 percent) and were as high as 23,000 ppm (2.3 percent). Treated soil was backfilled in an on-site containment cell. The removal efficiency of PCBs from the soil averaged 99.98 percent, relative to the project performance specification of 97 percent, and treated soil PCB concentrations were measured below 2 ppm. Approximately 30,000 gallons of PCB oil, desorbed from the feed material, were returned to the owner for subsequent off-site disposal. After modifications to the emissions control equipment, compliance with the 99.9999 percent destruction and removal efficiency (DRE) for PCBs in stack emissions required by the U.S. Environmental Protection Agency was achieved.     

Solvent cleaning of pole transformers containing PCB contaminated insulating oil

In 1989, it was discovered that the recycled insulation oil in pole transformers for electric power supply was contaminated with trace amounts of polychlorinated biphenyls (PCBs; maximum 50 mg-PCB/kg-insulation oil). In order to remove the PCBs from transformer components using n-hexane as a solvent, we investigated the relationship between progressive stages of dismantling and cleaning results. The results are summarized as follows: (1) Based on the cleaning test results, we made an estimate of the residual PCB amount on iron and copper components. By dismantling the test pole transformers into the "iron core and coil portion" and cleaning the components, we achieved a residual PCB amount that was below the limit of detection (0.05 mg-PCB/kg-material). To achieve a residual PCB amount below the limit of detection for the transformer paper component, it was necessary to cut the paper into pieces smaller than 5 mm. We were unable to achieve a residual PCB amount below the limit of detection for the wood component. (2) Compared to Japan's stipulated limited concentration standard values for PCBs, the results of the cleaning test show that cleaning iron or copper components with PCBs only on their surface with the solvent n-hexane will satisfy the limited concentration standard values when care is taken to ensure the component surfaces have adequate contact with the cleaning solvent.     

A Study of the Use of Alfalfa (Medicago sativa L.) for the Phytoremediation of Organic Contaminants in Soil

This article presents the results of a study that was conducted to determine the effectiveness of using alfalfa (Medicago sativa L.) to enhance the phytoremediation of three different types of chemical contaminants. The chemicals studied were trinitrotoluene (TNT), the polycyclic aromatic hydrocarbon (PAH) pyrene, and the polychlorinated biphenyl (PCB) Aroclor 1248. Experiments were conducted using soils that contained high and low organic matter content. The results indicated that recoveries of pyrene and TNT from soil were highly dependent on the soil organic matter content, while the recovery of PCB was not. Significantly low levels of pyrene and TNT were recovered from all treatments in the soil with 6.3 percent organic matter content compared to recovery levels found in soil with 2.6 percent organic matter. The presence of alfalfa plants had a significant effect on the transformation of TNT and PCB in the low organic matter content soil only and had no effect on the fate of pyrene. In the low organic matter soil, only 15 percent and 17 percent of the initial TNT and PCB levels, respectively, were transformed in the unplanted control soils compared to 66 percent and 77 percent in the alfalfa planted pots. In both soil types, pyrene dissipation could not be attributed to the presence of alfalfa plants. Overall, it was concluded that under high soil organic matter conditions, adsorption and covalent binding to the soil organic matter appeared to be the dominant force of pyrene and TNT removal. The effectiveness of using alfalfa to enhance PCB and TNT transformations was more significant in the lower organic matter soil; thus phytoremediation had a greater effect in soils with lower organic matter content. © 2001 John Wiley & Sons, Inc.     

Bench-scale studies on the simultaneous formation of PCBs and PCDD/Fs from combustion systems

The presence of endocrine disrupting chemicals (EDCs) in the environment has wide-ranging potential ecological and health impacts on animals and humans. A significant amount of experimental and theoretical work has been performed the examining formation and control of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs), which account for only part of the EDCs being emitted from combustion devices. Generally accepted mechanistic theories for PCDD/F formation propose heterogeneous reactions in the cooler regions of the combustor involving gas-phase organic precursors (such as chlorobenzenes or chlorophenols), a chlorine donor [such as hydrogen chloride (HCl)], and a flyash-bound metallic catalyst (such as copper chloride). There is evidence that some other proposed EDCs, including polychlorinated biphenyls (PCBs), are formed through a similar mechanistic pathway as PCDD/Fs. In addition, there is evidence that certain important steps in the catalytic reaction between the copper catalyst and the organic precursors may suggest a common rate limiting step for the heterogeneous formation of the previously mentioned EDCs. This paper reports on a bench-scale experimental study to characterize a newly built reactor system that was built to: produce levels and distributions of PCDD/F production similar to those achieved by previous researchers; verify similar responses to changes in independent variables; examine the hypothesis that PCB formation rates exhibit trends similar to PCDD/F formation rates as reactor variables are changed; and begin to explore the dependence of PCB formation on temperature and precursor type. The reactor system has been built, and initial reactor characterization studies have been performed. Initial experiments yielded results that support the hypothesis of a similar formation mechanism of PCBs and PCDD/Fs in combustors. Initial experiments uncovered potential deficiencies with the reactor system and the experimental procedures and have suggested corrective action to improve the experimental system.     

Hydrodechlorination/detoxification of PCDDs,PCDFs, and co-PCBs in fly ash by using calcium polysulfide

Dioxins like polychlorinated dibenzo-p-dioxins (PCSDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) are mainly emitted from waste incinerators (WIs) and have become an international research focus because of its serious concerns over the adverse health effects. The detoxification of PCCDs/Fs and PCBs is very difficult because of their stable chemical structure. A significant hydrodechlorination/detoxification of polychlorinated 1-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) were achieved in fly ash by using an aqueous mixture of calcium hydroxide and sulfur. Two different fly ashes were studied: originating from municipal waste incinerator (FA1) and industrial waste incinerator (FA2). They were heated with the aqueous mixture at 150 °C for 30 or 60 min with agitation. Higher decomposition (87%) and detoxification (87.7%) of PCDD/Fs and PCBs were achieved at 150 °C with two runs; every run was for 30 min, compared to one run for 60 min. FA2 gave higher decomposition and detoxification as compared to FA1, which might be due to higher metal content that played a catalytic role to decompose and detoxify the PCDDs, PCDFs and PCBs. The decomposition and detoxification of PCDFs in fly ash was higher than PCDDs and was augmented with increasing number of chlorides on aromatic compounds. As the highly significant decomposition and detoxification of higher concentration of PCDD/Fs and PCBs were achieved in 1 hour without additive catalyst and at low temperature of 150 °C, therefore, the developed method is cost effective and most suitable to apply on commercial/industrial level. The detail results of hydrodechlorination/detoxification of PCDD, PCDFs at different conditions are described and its mechanism is discussed.     

Remediation of PCB-contaminated sediments: Volatility and solubility considerations

Through volatilization and long distance atmospheric transport, polychlorinated biphenyls (PCBs) have been redistributed throughout the global environment. Over the last 70 years, these compounds have permeated every known environmental niche including the remote polar regions of the globe. In this article, the solubility and volatility of the PCB congeners are reviewed relative to the remedial technologies that are currently in use or under consideration. The following discussion focuses primarily on the management options for PCB-contaminated, subaqueous solids that require removal, dewatering, drying, and other treatment to degrade the target contaminants and/or containment in engineered facilities including constructed islands, upland secure landfills and subaqueous pits. Environmental mobility resulting from natural and engineered processes is discussed in relation to the potential for contributing to the global loading and redistribution of PCBs. Additionally, select emerging technologies and management options are reviewed relative to their potential to produce secondary environmental impacts resulting from the soluble and/or volatile redistribution of PCBs. Based on a lack of long-term experience and the recognition that contaminants will remain unaltered for decades, technologies involving engineered containment structures should be considered temporary remedial measures until cost-competitive, destructive processing of contaminated sediments is feasible.     

On-site remediation of PCB contamination using transportable incineration systems

Many Superfund or hazardous waste sites prove to be excellent candidates for remediation using transportable incineration. Transportable incineration has been selected as the alternative of choice to remediate numerous sites throughout the United States. There are a number of firms that provide mobile and transportable incineration equipment and services. A variety of treatment systems are available, including rotary kilns, fluidized beds, and infrared incinerators. Roy F. Weston, Inc., has been instrumental in the development, design, permitting, construction, performance testing, and operation of hazardous and toxic waste thermal treatment systems. Weston owns and operates two high-temperature transportable incineration systems (TISs). The first system is Weston's seven-ton-per-hour (tph) TIS-5. The second is the TIS-20, with a design capacity of up to 30 tph. These units are typical rotary kiln incinerators, the most flexible, adaptable type of incineration unit. This article discusses Weston's use of these incinerators to remediate soils at sites contaminated with polychlorinated biphenyls (PCBs).     

Progress toward remediation of the Sydney Tar Ponds: A major Canadian PCB/PAH “superfund” site

The Muggah Creek estuary in Sydney, Nova Scotia, received liquid and solid wastes from a steel mill and its associated coke ovens for approximately 100 years. This resulted in pollution of soils and sediments with polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), heavy metals, and other pollutants, including those in untreated domestic wastewaters. The Canadian federal and Nova Scotia provincial governments organized the Sydney Tar Ponds Agency (STPA) to develop a remediation approach for the Coke Ovens site soils and Sydney Tar Ponds sediments. The STPA developed a remediation approach for the Sydney Tar Ponds sediments, involving solidification/stabilization (S/S) through mixing cement and other materials into the sediments, and then capping them as a waste pile. High‐density polyethylene (HDPE) plastic sheeting vertical barriers are proposed to be used to divert groundwater and surface water from entering into the S/S‐treated sediments and to collect any water and associated pollutants released from the S/S‐treated sediments. The Coke Ovens site soils are proposed to be landfarmed to reduce some of the PAHs and other pollutants and then capped with a layer of soil. This remediation program is estimated to cost on the order of $400 million (CAN). This article presents a review of the significant potential problems with the STPA proposed remediation strategy of the Sydney Tar Ponds sediments and Coke Ovens site soils. © 2006 Wiley Periodicals, Inc.     

Practical Perspectives of 1,4‐Dioxane Investigation and Remediation

1,4‐Dioxane (dioxane) is a contaminant of emerging concern that is classified by the U.S. Environmental Protection Agency as a likely human carcinogen. Dioxane has been used as a minor or major ingredient in many applications, and is also generated as an unwanted by‐product of industrial processes associated with the manufacturing of polyethylene, nonionic surfactants, and many consumer products (cosmetics, laundry detergents, shampoos, etc.). Dioxane is also a known stabilizer of chlorinated solvents, particularly 1,1,1‐trichloroethane, and has been commonly found comingled with chlorinated solvent plumes. Dioxane plumes at chlorinated solvent sites can complicate site closure strategies, which to date have not typically focused on dioxane. Aggressive treatment technologies have greatly advanced and are clearly capable of achieving lower parts per billion cleanup criteria using ex situ advanced oxidation processes and sorption media. In situ chemical oxidation has also been demonstrated to effectively remediate dioxane and chlorinated solvents. Other in situ remedies, such as enhanced bioremediation, phytoremediation, and monitored natural attenuation, have been studied; however, their ability to achieve cleanup levels is still somewhat questionable and is limited by co‐occurring contaminants. This article summarizes and provides practical perspectives on dioxane analysis, plume stability relative to other contaminants, and the development of investigation tools and treatment technologies.