Requirements soil decontamination

Electroremediation using electrical current is the final purification method discussed in this chapter. Here, an array of anodes are placed in the soil opposite an array of cathodes. When electric potential is apphed the following processes occur electrolysis of water in the soil, dissolution of polluting ions, migration of ions under the influence of the apphed potential field, and reduction or pH based precipitation at the cathode [68,69]. This technique, also known as electroreclamation or electrochemical soil decontamination, does not require a membrane however, improved electroremediation has been reported when ion-exchange membranes were incorporated into the system [70]. The function of the membrane is to retain OH ions produced at the cathode. Migration of these OH ions is prevented to avoid precipitation of the heavy metal ions in the sod. 

The triplate line is suitable for those soil decontamination applications where the contaminants have penetrated more than three feet below the surface and for contaminants that require treatment temperatures in excess of 130° to 150°C,... 

Clean up in such a way tliat the hazardous material is removed and does not produce a future danger. It may be necessary to pump out a hazardous liquid or to remove contaminated soil, etc. Decontamination procedures may be necessaiy. See EPA s Standard Operating Safety Guides for instructions for decontamination required following exposure to different danger levels of liazmds... 

SFE. SFE has been established as the extraction method of choice for solid samples. The usefulness of SFE for soil samples has been demonstrated for carbamate,organophosphorus and organochlorine pesticides. However, SFE is more effective in extracting nonpolar than polar residues. In order to obtain a greater extraction efficiency for the polar residues of imidacloprid, the addition of 20% methanol as modifier is required. Extraction at 276 bar and 80 °C with a solvent consisting of supercritical carbon dioxide modified with methanol (5%) for 40 min gives a recovery of 97% (RSD = 3.6%, n = 10). It is possible to use process-scale SFE to decontaminate pesticide residues from dust waste. ... 

The TSDF standards also establish requirements to ensure that hazardous waste management units are closed in a manner that protects human health and the environment. The closure provisions require the facility to stop accepting waste remove all waste from management units and decontaminate all soils, structures, and equipment. Some units (i.e., land treatment units, landfills, and surface impoundments) serve as places for the final disposal of hazardous waste. These land disposal units must comply with additional postclosure requirements to ensure proper long-term unit maintenance. 

Chemical remediation refers to the application of various minerals or chemicals to adsorb, bind, precipitate or co-precipitate trace elements and heavy metals in soils and waters thereby reducing their bioavailability, toxicity, and mobility. In situ immobilization refers to the treatment of contaminants in place without having to excavate the soils or waste, often resulting in substantial cost savings. However, in situ immobilization or extraction by these physicochemical techniques can be expensive and are often only appropriate for small areas where rapid and complete decontamination is required. 

Phytoremediation methods for radionuclide decontamination do not involve hyper-aeeumulators, except possibly for uranium. Plants require a long period of eontact with a contaminant to evolve the ability to hyper-aeeumulate, and most uranium ores are located underground and so are not in eontaet with plants. Soils with high concentrations of uranium are present only where uranium is or has been mined or processed, but these have only been in existenee for a few deeades. 

The Facility Closure Plan includes two sampling and analysis plans. The first, Sampling and Analysis Plan for HWMU Closure (Appendix 2 in the Plan), includes requirements and procedures for conducting field sampling operations and investigations of soils and structures associated with the MDB and the HWMUs, as well as data quality objectives and field sampling protocols that could be used to verify decontamination (U.S. Army, 2000a). 

The closure activities at J AC ADS consist of decontamination and removal of process equipment and building structures and some soil removal and disposal. Although no requirement for groundwater treatment is anticipated at Johnston Island, other CSDP disposal sites might require groundwater treatment, which would affect the closure process and the ultimate postclosure monitoring at those sites. 

Several existing protocols require a solvent (acetone, methanol, isopropanol) rinse as part of equipment decontamination for VOC sampling and 1 10 percent hydrochloric or nitric acid rinse for metal analysis sampling (DOE, 1996 USACE, 1994). These practices, successful as they may be in removing trace level contaminants, create more problems than they are worth. Organic solvents are absorbed by the polymer materials used in sampling equipment construction and appear as interferences in the VOC analysis. Acid destroys the metal surfaces of soil sampling equipment and induces corrosion. The use of solvents and acids is a safety issue and it also creates additional waste streams for disposal. 

If decontamination ( hotline ) procedures are required, the containers with the samples will leave the contaminated area only after decontamination is performed. All disposable items for sample collection will be left inside the hot area. Blank samples of soil or water are taken (at presumably not contaminated points) outside the hot area. 

In the flow diagram shown in Fig. 1, only stages I, II and III are required in the case of a 100% sand soil. For soils containing materials other sand — depending on the content of other soil particles, such as clay or silt - the integral process with all 6 stages can be used to ensure a good decontamination of the final solid residues. 

Management of Contamination. Resuspension of materials into the atmosphere would be the most serious hazard and extensive monitoring would be required. Wetting down the area with airborne water tankers might be required. If the levels of activity allow cleanup operations to proceed, soil may have to be removed and buried in sealed containers. Individual countries establish the levels to which decontamination is carried out for peacetime use. 

The Portable Unit arrived at the Times Beach Dioxin Research Facility on July 8, 1985, to demonstrate decontamination of the dioxin laden soil. The Unit was set up and made ready for operation within a few hours after arrival to the site. This rapid setup demonstrated its unique capability for mobility. The testing personnel followed a safety plan developed by the Missouri DNR which included pretest physical examinations, use of Class C safety clothing, and vital sign monitoring and rest periods for personnel. The weather was hot and humid which required the work in the trailer to be limited to 20 minutes at a time. 

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 effectiveness of thermal desorption to decontaminate soil containing HO and of UV photolysis to destroy HO toxic constituents has been demonstrated in bench- and pilot-scale tests. Some additional technical information is needed for a complete evaluation of the process and to provide the basis for design of a full-scale system for on-site remedial action. This project illustrates the requirements for developing and implementing new process technology for solving contaminated-soil environmental problems. Only through such demonstration efforts can more cost-effective and environmentally sound remedial action alternatives be made available. 

Some experiments have been made to evaluate if the application of electric fields could enhance phytoremediation, or plant uptake of heavy metals, of the contaminated sites (O Connor et al, 2003 Zhou et al, 2007). Cu uptake was significantly higher with ryegrass root when stimulated by an electric field. On the other hand, the Cd uptake seemed to be unaffected by the electric field. Anyway, it was concluded that the combination of the two techniques represented a very promising approach to the decontamination of metal-polluted soils, which would require validation in field conditions. It was also possible to incorporate sulfur-oxidizing bacteria and EK to enhance copper removal from contaminated sulfur-containing soil (Maini et al., 2000). 

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