Dioxin remediation

Baird is the 20-acre site of a former chemical mixing and batching company. Poor waste disposal practices resulted in the contamination of groundwater, soil, the municipal water supply, and a brook adjacent to the site. Over one hundred contaminants, including chlorinated and nonchlorinated volatile organics, heavy metals, pesticides, herbicides, and dioxins, had been identified in site soil and groundwater. Remediation activities included soil excavation and incineration, and groundwater treatment (the audit focused on the soil excavation and incineration... 

Aquaplant is not suitable for the remediation of aromatic hydrocarbons benzene, toluene, ethylene, and xylene (BTEX), polychlorinated biphenyls, volatile chlorinated hydrocarbons, pesticides, dioxins, and furans. 

Dual-phase extraction cannot remediate heavy chlorinated compounds, pesticides, or heavy hydrocarbons including polychlorinated biphenyls (RGBs), dioxin, fuel oil No. 6, or metals (with the possible exception of mercury). High-velocity pump systems (such as liquid ring vacuum pumps) tend to form emulsions, especially when diesel fuel is part of the recovered fluids. The problem of emulsion can be solved with prepump separation or a de-emulsification unit. 

KAL con s thermal units are applicable to treatment of hydrocarbon-contaminated soils but may not be used to remediate soils contaminated with polychlorinated biphenyls (PCBs), radioactive isotopes, or dioxins. Pesticides and herbicides can be treated by low-temperature thermal desorption, but special permitting is required and may be difficult to obtain. 

The technology can be used in any type of soil, including low-permeability clays. According to the vendor, this technology can be used to treat polychlorinated biphenyls (PCBs), dioxins, chlorinated solvents, pesticides, and herbicides. The thermal blanket technology has been demonstrated to remediate PCB-contaminated soil to a level of 2 ppm. 

Dehalogenation occurs by either the replacement of halogen molecules or the destruction of the contaminant. Soil and sediment that are contaminated with chlorinated organic compounds, especially PCBs, dioxins, and furans, can be remediated through dehalogenation. The contaminated soil is screened, processed with a crusher and pug mill, and mixed with sodium bicarbonate. The mixture is heated to above 330°C (630°F) in a reactor to partially decompose and volatilize the contaminants. The volatilized contaminants are captured, condensed, and treated separately. 

Luo, Y.M., Teng, Y., Li, Q.B., Wu, L.H., Li, Z.G., Zhang, Q.H., 2005. Soil environmental quality and remediation in Yangtze River Delta region I. Composition and pollution of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in a typical farmland. Acta Pedol. Sin. (Chinese) 42, 570-576. 

However several POPs, particularly the OCPs and dioxins, remain at low levels in the Australian environment and several remain persistent at low levels in body fats and fluids of Australians. The levels reflect the past use and persistence of OCPs in the Australian environment, contamination of the food chain and the capacity of the body to metabolise and store in body fats. The dioxins remain due to the ubiquitous nature of their sources with combustion as a major source and their persistence. Future trends are likely to mean very low-level residues in human fats of DDE, cyclodienes, HCB, HCHs and dioxins in the long term. Their rate of decline will probably depend on removing HCB from chlorinated industrial chemicals and OCPs from the environment (e.g. remediation of contaminated soils) by hazardous waste treatment methods (e.g. physical, chemical and biological degradation or fixation) or secure landfill. 

Rogers CJ, Komel A, Peterson RL. 1987. Mobile KPEG destruction unit for PCBs, dioxins and furans in contaminated waste. Presented at the 13th Annual Research Symposium Land disposal, remedial action Incineration and treatment of hazardous wastes, Cincinnati, Ohio. May 6-8, 1987, 361-365. 

Processes can be modified to deliver targeted remediation levels. Many different soil contaminants have been treated. These include PCBs, polycyclic aromatic hydrocarbons (PAHs), chlorinated solvents, dioxins, furans, pesticides, hexachlorobenzenes, BTXs, volatiles, and semi volatiles. After treatment, the soils pass all toxicity characterization leachate procedure (TCLP) criteria for replacement or nonhazardous waste landfill disposal. Specific examples of soil and sludge treatment will now be given. Table 3 contains data from several PCB remediation projects. 

A New Bedford Harbor Sawyer Street site in Massachusetts has been designated as a superfund site due to PCB contamination of river sediments. Commodore was one of three companies chosen to conduct demonstration studies on-site under contract to Foster Wheeler Environmental Company. The river sediment was first washed with diisopropylamine by the Ionics RCC B.E.S.T process [35], producing an oil concentrate. The PCB level in the B.E.S.T concentrate was approximately 32,800 ppm. Dioxins/furans (TEFs) were also present at 47 ppm. This concentrate was reacted with SET in the SoLV process to destroy the PCBs and dioxins (Table 4). After treatment, the PCB level was 1.3 ppm, well below regulatory requirements for disposal in nonhazardous waste landfills. Dioxins were also readily remediated. This study also illustrates that the SoLV process can remove metals from substrates. The concentrate received was found to have lead, arsenic, and selenium in high parts-per-billion levels. After treatment with the SoLV process, the levels were below detection limits. The metals were... 

Contaminated transformer oils and cutting fluids have been remediated readily using Na/NH3 in a 1200-L equipment (Table 7). Oils containing over 20,000 ppm of PCBs have been detoxified to levels below 0.5 ppm. Typically from 2 to 4 wt.% Na in liquid NH3 was used. The SET process was also used to remediate dioxins in waste oil from the McCormick and Baxter Site in Stockton, CA. As shown in Table 8, dioxins were reduced to parts-per-trillion (ppt) levels. 

Gmden C., Fu Q. S., Barkovskii A. L., Albrecht 1. D., Lynam M. M., and Adriaens P. (2003) Dechlorination of dioxins in sediments catalysts, mechanisms, and imphcations for remedial strategies and dioxin cychng. In Dehalogenation ... 

Finnecy, E. E., and Johnstone, E. T. C. (1988). Remedial measures proposed for the rehabilitation of a dioxin contaminated site in New South Wales, Australia. In Contaminated Soil 88, ed. Wolf, K., van den Brink, W. J., and Colon, F. J., Proc. 2nd International TNO/BMFT Conference on Contaminated Soil, Hamburg, Germany, Apr. 

Soil contamination also can be very difficult to detect. New analytical methods have made it possible to detect and analyze dioxins, polyaromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). Analytical techniques have made it possible to detect the presence of these substances, determine whether remediation is needed, and evaluate the extent to which it has been carried out. Chemistry has provided or contributed to the remediation technologies that have been developed,... 

Pentachlorophenol (PCP) Users. PCP has been used as a wood preservative for many years. PCP contains octa-, hepta-, hexa-, and pentachlorinated dioxins. Since PCP was applied generally in an oil solution, spills and discharges from this operation have led to widespread migration of PCP and its impurities. The magnitude of these environmental discharges and possible remedial measures are being examined by U.S. EPA and responsible parties. 

During the last decade, various remedial actions were carried out on dioxin-contaminated wastes in the United States and Europe. Historically, building rubble from industrial accidents was used as fill or disposed in the ocean. In 1977, about 2.2 million gallons of Agent Orange and similar herbicide formulations was incinerated on the ship Vulcanus in the Pacific (1). This solution was simplified by the ability to transfer the waste to the ship at a remote location in the Pacific and by the large quantity of liquid waste, which made the incineration on ship economically possible. The destruction efficiency of this at-sea-incineration was about 99.9% according to the limits of analytical detection at that time. 

Military Sites Contaminated with 2,3,7,8-Tetrachlorodibenzo-p-dioxin Permitting Remedial Action Research... 

Thermal treatment appears to be the most readily available remedial action technology for dioxin. However, no data are available to confirm the maintainability, reliability and cost-effectiveness of transportable commercial systems. Through a competitive process, the USAF selected ENSCO Corporation for a full-scale field test of their rotary-kiln combustor. The test will be conducted at the NCBC, Mississippi and will involve treatment of approximately 9000 cubic yards of contaminated soil. An intense analytical program and engineering failure mode analysis will support the project. Testing is planned for November 1986 - March 1987. 

A Sampling Strategy for Remedial Action at Hazardous Waste Sites Cleanup of Soil Contaminated by Tetrachlorodibenzo-p-dioxins," Chapter 10 in Chlorinated Dioxins and Dibenzofurans in Perspective" C. Rappe, G. Choudhary, and L. H. Keith, Eds (Chelsa, MI Lewis Publishers, Inc., 1986). 

---