Thermal desorption contaminant recovery

Thermal desorption treatment is generally considered to be an alternative to incineration. Thermal desorption operates at much lower temperatures than incineration and keeps the heating systems independent of the wastes, which minimizes off-gas production. The technology can be used as a waste minimization process, isolating and concentrating waste constituents, or as a product recovery process. Thermal desorption can also be used to separate contaminants in mixed waste streams by removing volatile constituents. 

Mercury Recovery Services, Inc. (MRS), has developed the Mercury Removal/Recovery Process (MRRP) to treat media contaminated with mercury. The ex situ process uses medium-temperature thermal desorption to remove the mercury from contaminated wastes. Process wastes are heated in a two-step process to recover metallic mercury in a 99% pure form. MRS claims MRRP can be applied to soils, activated carbon, mixed waste, catalysts, electrical equipment, batteries, lamps, fluorescent bulbs, mercurous and mercuric compounds, mercury-contaminated waste liquids, and debris. 

The thermal recycling system (TRS) is a thermal desorption unit designed for the on-site, ex situ remediation of mercury from contaminated soils. The system volatilizes and then condenses mercury for recovery. The TRS processes contaminants in a nonreactive atmosphere. It uses indirect heat sources to desorb contaminants and recovers 90% of the contaminants. 

The SAREX process is a trailer/skid-mounted, modular system designed for on-site, in-line separation and resource recovery of oily waste sludges and contaminated soils. This process provides dewatering and thermal desorption to maximize the recovery of oil while obtaining substantial reduction in volume and contaminant concentrations. The SAREX process includes the MX-1500 centrifuge, the MX-2000 low-temperature thermal dryer, and the MX-2500 medium-temperature thermal desorber. The MX-1500 centrifuge is used to separate the solids from the... 

One technology suitable for remediating these sites is thermal desorption, which heats soils and sludge to remove volatile contaminants such as VOCs, SVOCs, PAHs, PCBs, pesticides, mercury, and mixed waste for recovery or further treatment. The success of thermal desorption is evidenced by how frequently it has been used since its initial demonstration. From fiscal years (October 1 through September 30) 1982 through 1999, thermal desorption was used in 14% of Superfund... 

Some relatively pure liquids recovered from the environment can be distilled or rereflned and reused. For example, petroleum products recovered from some waste sludge by thermal desorption or waste oils collected from automobiles can be rerefined to make a usable product. The potential to recover usable product from material spilled into the environment can be limited, however. Once spilled, a solvent or petroleum product begins to change physically and chemically. The liquid can become contaminated with water, dirt, or other substances. After some time, chemical and biochemical reactions will alter the chemical composition of the material. Further, the volume recovered from spill cleanup may be relatively small and a rereflning facility may not be located nearby. As a result, it may be more feasible simply to ship the waste for energy recovery. 

Thermal treatment is used to destroy, break down, or aid in the desorption of contaminants in gases, vapors, Hquids, sludges, and soHds. There are a variety of thermal processes that destroy contaminants, most of which are classified as incineration. Incineration HteraHy means to become ash (from Medieval Latin, incinerare in or into ashes). With respect to the incineration of hazardous wastes regulated in the United States, however, there is a strict legal definition of what constitutes an incinerator. The Resource Conservation and Recovery Act (RCRA) definition of incinerator at 40 CFR 260.10 is... 

Headspace analysis is the method of choice for determining volatile organic compounds in soil [178-183]. A limitation of this method is the incomplete desorption of the contaminants in soil-water mixtures, but this problem can be overcome through the addition of methanol to the sample [181]. Good recoveries of volatile organic compounds in soils were obtained via thermal vaporisation of the sample followed by Tenax GC trapping and gas chromatography-mass spectrometry. 

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