Contaminated soil stabilization

Solidification/Stabilization technologies are techniques designed to be used as final waste treatment. A major role of these processes is posttreatment of residuals produced by other processes such as incineration or chemical treatment. In some cases, solidification/ stabilization processes can serve as the principal treatment of hazardous wastes for which other detoxification techniques are not appropriate. High volume, low toxicity wastes (such as contaminated soils) are an example of this application. 

Willumsen and Karlson [125] screened 57 PAH-degrading bacteria isolated from PAH-contaminated soil for the production of biosurfactant compounds. The majority of the strains isolated on phenanthrene, pyrene, and fluoranthene were better emulsifiers than surface-tension reducers, and the stability of the... 

Extent of contamination/plume stability Hydrocarbon type Chromatographic evidence Hydrocarbon concentration Soil pH... 

Similarly, a GLP study on the fate of a pesticide should not be conducted using the same equipment as routine analysis of pesticides in soils. Stability studies must be set up in a way that routine work in the lab will not contaminant the test materials. 

T0313 Forrester Environmental Services, Inc., Heavy-Metal Stabilization T0488 Lynntech, Inc., Electrokinetic Remediation of Contaminated Soil T0600 Perma-Fix Environmental Services, Inc., Perma-Fix Process... 

Asphaltic metals stabilization is a stabilization technology for metal-contaminated soils in which the soils are combined with predetermined amounts of aggregates and asphalt emulsions to... 

Phytoremediation is the use of plants to treat or stabilize contaminated soils, sediments, or water. Plants provide and support remediation processes in many ways. Common applications of phytoremediation-based systems include remediation of contaminated soil and groundwater, reuse of municipal wastewater and biosolids, reuse of industrial wastewater and by-products, alternative landfill capping and erosion control, and landfill leachate reuse. 

The vendor states the cost of full-scale MERS treatment depends on soil characteristics, the concentration and chemical state of the targeted metal contaminants, the concentration of unregulated metals, and the cleanup objectives. The vendor claims the cost of MERS processing is competitive with the cost of landfill disposal, soil stabilization, and soil washing (D124538,... 

SOLFIX is an ex situ stabilization technology that treats heavy metals by reacting contaminated soils and sediments with cement, pozzolanic materials, and other additives to chemically immobilize contaminants into an insoluble form. SOLFIX can be used either as a stand-alone technology or it can be incorporated with Hydro-SEP (a sediment washing technology) and ORG-X (a solvent extraction technology) into a three-step remediation process termed integrated sediment decontamination system (ISDS). 

Stabilization/solidification (S/S) is a proven technology for the in sitn or ex situ treatment of hazardous wastes and hazardous waste sites. It uses additives or processes to physically and/or chemically immobilize the hazardous constituents of contaminated soils, sludges, sediments, or even hquid wastes. The object of this technology is to prevent the migration of contaminants into the environment by forming a sohd mass. Contaminants are trapped and immobilized within the existing medium, rather than removed via chemical or physical treatments. 

MTT is commercially available in several forms. Enviro-Blend is used as a remediation technology to treat contaminated soils, sludges, and sediment. This mixture also serves as a pollution prevention technology to treat industrial waste streams. Enviro-Blend is distributed exclusively by American Minerals, Inc. The Enviro-Prep System stabilizes the lead in paint and is commercially available through Hoffer s Coatings, Inc. Enviro-Prep Special is another MTT product that is used to stabilize lead contamination in utility access points. 

In 1994, a US unit was used to remediate PCBs at the Coal Creek Superfund Site in Chehalis, Washington. Approximately 33,000 tons of soils were excavated, and highly contaminated soils were separated from soils with minimum contamination. Approximately 9700 tons were treated with the nS-5 the remaining soil was stabilized and backfilled into an in-site containment cell (D115377). The actual cost for remediation at the site was approximately 8,100,000, or approximately 830 per ton. The extensive excavation and material handling at the site added to the total remediation cost (D184672, p. 77). 

At a fonner lead smelting facility in Benicia, California, approximately 11,500 tons of lead-contaminated soil were treated and placed in an on-site repository. According to the vendor, the stabilization costs were 70 per tons of soil treated. The contracting and reagent costs for the project were 805,000 (D113382, p. 9). 

Approximately 4000 tons of copper-contaminated soils from a former electroplating plant in City of Industry, Cahfomia, were stabilized using the STC Remediation, Inc., technology. According to the vendor, the stabihzation costs were 70 per ton of soil treated. Contracting and reagent costs were 37 per ton of soil treated (D113382, p. 12). 

United Retek Corporation (URC) has developed asphalt emulsion stabilization technology for the ex situ treatment of soils contaminated with organic compounds and heavy metals. In this ambient temperature technology, the targeted contaminants are stabilized and solidified in an asphalt emulsion. According to the vendor, this emulsion can be used for pavement after the material has been cured. The technology has been used in full-scale site remediation projects and is commercially available. 

The use of phosphate has been widely evaluated and subjected to field trials for Pb-contaminated soils. Most treatment systems involve excavation, pug milling of the soil with the stabilization agent, and either replacement or landfill disposal. Occasionally, for larger sites and deeper contamination, in situ mixing with large augers is used. 

Phosphate is widely used as a chemical stabilization agent for MSW combustion residues in Japan and North America and is under consideration for use in parts of Europe. The application of this technology to MSW ashes generally parallels its application to contaminated soils. Metal phosphates (notably Cd, Cu, Pb and Zn) frequently have wide pH distribution, pH-pE predominance, and redox stability within complex ash pore water systems. Stabilization mechanisms identified in other contaminated systems (e.g., soils), involving a combination of sorption, heterogeneous nucleation, and surface precipitation, or solution-phase precipitation are generally observed in ash systems. 

Xenidis, A., Stouraiti, C. Paspaliaris, I. 1999. Stabilization of oxidic tailings and contaminated soils by monocalcium phosphate monohydrate addition the case of Montevecchio (Sardinia, Italy). Journal of Soil Contamination, 8, 681-697. 

Full-scale separation/washing and bioslurry reactor operations have been used to treat creosote-contaminated soil at the former Southeastern Wood Preserving Site at Canton, Mississippi (Jerger et al., 1994 Woodhull Jerger, 1994). Here, an estimated 10 500 yd3 of soil and sludge were excavated from various process areas, stabilized with kiln dust and stockpiled for subsequent treatment. Based on the results of preliminary bench studies, four 680 000 liter reactors were eventually established to handle 7050 yd3 of the screened (200-mesh) soil fraction at a solids content of 20-25%. Other oil fractions and waters were handled separately (data and costs not reported). 

This investigation was conducted as two separate experiments. One set of experiments was performed on synthetic environmental soil samples created to reflect the composition and concentration of "typical" Superfund site soils. The other set of experiments was performed on contaminated soils from an actual Superfund site. Both experiments were concerned with the ability of the CHEMFIX process to solidify and stabilize the heavy metals contaminants in the soils. 

In situ solidification/stabilization refers to the injection and mixing of binders into contaminated soils and sediments. Although the process can be effective, obstructions, deep contamination, shallow water tables,... 

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