Dioxin-contaminated waste disposal

Unwillingness by commercial waste disposers to accept dioxin-contaminated waste, a decision which led to testing of many novel dioxin treatment schemes. 

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. 

Current Cleanup Options for Dioxin Wastes. Governmental regulations and dioxin s negative image currently prevent off-site disposal or treatment of dioxin-contaminated wastes. In response to a need to destroy dioxin wastes, a number of novel process adaptations have been proposed and tested. These processes include incineration, physical-chemical, and biological processes. In addition, on-site containment, storage, and monitoring remain economic alternatives. 

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... 

TCP), and pentachlorophenol (PCP), in order of abundance. Minor amounts of other trichlorophenols and dichlorophenols may also be present, as well as recalcitrant polychlorinated phenoxyphenols (PCPPs) and PCDD/Fs as impurities [75, 76]. In Finland, approximately 30,000 tons of CP products were used between 1934 and 1988, when they were banned because of their potential toxicity to humans and the environment [77, 78]. The careless manufacturing and application of wood preservatives together with the lack of suitable waste disposal caused massive contamination of river sediments and sawmill sites. For example, the river Kymijoki in southern Finland was identified as the largest source of dioxins accumulating in fish in the entire Baltic area. Similar products were used in other European countries, especially Nordic countries with a large forestry industry, such as Sweden [79]. 

Dioxin. Two years ago, EPA promulgated a rule prohibiting Vertac Chemical Corporation from disposing of waste contaminated by dioxin. Other parties intending to dispose of similarly contaminated wastes were required to notify EPA 60 days in advance of their intentions. This order may have prevented some exposure to this highly toxic substance, though the human health impact of this single prohibition cannot be calculated. 

Dioxins (PCDDs) occur as contaminants in many agricultural pesticides and can occur in the environment as a result of pesticide usage, although many other industrial sources and natural sources have been identified. The National Dioxins Program (2004) has revealed that major sources of dioxins in the environment are uncontrolled combustion sources such as bush fires and accidental fires which contribute 70% of the total to the air and 80% to the soil whereas waste disposal and land filling contribute 75% of the total to water. 

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. 

This report presents the results of EPA s investigation of potential 2,3,7,8-TCDD (dioxin) contamination. The study represents a two-year, nationwide, multi-media evaluation initiated at the request of the U.S. Congress in 1983. The majority of dioxin contamination at Tier 1, la, 2 and 2a sites remained on-site. At sites where concentrated 2,A,5-TCP production wastes were stored or disposed, 2,3,7,8-TCDD concentrations were as high as 356 ppm. At most sites, however, 2,3,7,8-TCDD levels in soil were usually in the ppb range. In fish samples from nearby lakes and streams, 2,3,7,8-TCDD was measured in terms of ppt. Only two Tier 3 sites were extensively contaminated and comprised large facilities handling... 

Of those sites where dioxin was detected at levels of concern, the most common materials contaminated were soil and dust. At certain sites, production waste, contaminated equipment, and contaminated building materials were found. As expected, these sites were generally the production facilities of Tiers 1 and 2 and those waste disposal sites where intact waste or scrapped equipment was stored or disposed. The majority of dioxin contamination at Tier 1, la, 2 and 2a sites remained on-site. Furthermore, the 2,3,7,8-TCDD was usually confined to areas where waste materials were stored, loaded, processed, or, in the case of 28 Missouri sites, sprayed on roads to control dust. In seven cases, offsite migration at levels of concern has been confirmed. They are ... 

Moreover, this rule replaced the regulation concerning the disposal of 2,3,7,8-TCDD-contaminated waste under the Toxic Substances Control Act (TSCA)—the so-called Vertac Rule—which was revoked on the same date. Unfortunately, the dioxin-listing rule currently does not cover thermally stressed PCBs, a source of CDDs and CDFs... 

The Portable Unit has successfully demonstrated its capability for thermal treatment of hazardous wastes at the source of the material. This type of on-site treatment would eliminate the need of transportation of hazardous materials to a distant site of stationary treatment equipment. The Portable Unit also has demonstrated that it can be moved to a site and be ready to treat material very quickly, a capability which will be very important in operation of full scale equipment. The on-site treatment of the Times Beach dioxin contaminated soil resulted in no dioxin detected in any of the incinerator effluent streams. The product of the testing activity was soil with no detectable level of dioxin. Dioxin contaminated soil thermally treated in this manner will yield soil which can be disposed as non-hazardous material. The decontamination was performed without exceeding RCRA requirements for particulate emissions and with dioxin destruction efficiencies surpassing the required percentage. The overall conclusion was that the infrared incinerator can very effectively remove dioxin from contaminated... 

The vendor claims that the TDR process can be used to treat soil and sludge contaminated with polychlorinated biphenyls, polynuclear aromatic compounds, solvents, dioxins, furans, organic pesticides and herbicides, solvents, petroleum wastes, as well as nonhalogenated volatile and semivolatile compounds. The treated residuals from the process include recovered water, oil that can be used for recycling as an alternative fuel or for recycling or can be disposed, and clean soil that can be used as backfill. The volume of treated sludge is reduced by as much as 95% by this thermal process, depending on the initial level of contaminants. 

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... 

Category 1 materials (animal byproducts presenting highest risk, e.g., transmissible spongiform encephalopathies or scrapie residues of prohibited substance, e.g., hormone used for growth promotion or environmental contaminants, e.g., dioxins, PCBs) must be completely disposed of as waste by incineration or landfill after appropriate heat treatment. 

On December 15, 1983, EPA issued a "national dioxin strategy" for investigating, identifying, and cleaning up sites contaminated by dioxin (1). Within the framework of this strategy was a plan that called for research to be conducted on the technical feasibility and economics of alternative methods for disposal and destruction of wastes and soils contaminated by dioxin. 

Incineration does not destroy lead and other inorganic chemicals, and they will be emitted or concentrated in the ash. In addition, some organic chemicals form products of inconplete combustion (PICs), which may be more toxic than the chemical contaminant. Incineration of PCBs and some other chlorinated aromatics, for example, can form extremely toxic polychlorinated dibenzo[/>]dioxins and furans. Commercial disposal may be preferred for such waste. 

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