Sediments remediation remedial technologies

The bio availability of organic compounds in soils/sediments to microbes, plants, and animals is important from the perspective of remediation and risk assessment. Cleanup technology (ex situ or in situ) of contaminated soils and bottom sediments requires mass transport of contaminants through the solid materials, which in turn depends on sorption/desorption kinetics. 

Generally, slow sorption or desorption has made complete remediation technology difficult. However, there have recently been legitimate questions raised by some researchers [163,187] about whether we even need to be concerned about residues that desorb so slowly and thus are apparently largely bio-unavailable. At a minimum, it is important that we understand the factors which govern slow sorption/desorption rates, their kinetics and causes at the intra-particle level of different solid phase materials (e.g., surface/subsurface and aquatic sediment particles), and how these phenomena can relate to contaminant transport, bioavailability, toxicity, remediation, and risk assessment modeling. 

M Company, 3M Empore Extraction Disk BioGenesis Enterprises, Inc., Soil and Sediment Washing Process Bioremediation Technology Services, Inc., BTS Method BioSystems Technology, Inc., Chlorinated Solvent Remediation (CSR)... 

Electrokinetic treatment can be used to remediate soils, sludges, and sediments contaminated with heavy metals and organic hydrocarbons. Electrokinetic treatment works well on clay-type soils with low hydraulic permeability, which are difficult to treat using other in sitn technologies. Electrokinetic permeabilities for aqueous systems in clays have been demonstrated to be up to 1000 times greater than normal hydraulic permeabilities, and some heavy metals have exhibited removal efficiencies of up to 100%. 

This technology is not suitable for very dense, low-permeability soils and sediments. However, electrokinetic transport could be used to remediate contaminated clay formations within a more permeable aquifer. 

Fluor Daniel GTl, Inc. (now part of the IT Corporation), has developed in situ geochemical fixation technology to immobilize metallic contaminants in soil, sediment, sludge, and groundwater. The technology uses a site- and contaminant-specific combination of reagents to convert ionic contaminants to less soluble forms. In situ geochemical fixation has been used to remediate sites contaminated with chromium, uranium, molybdenum, and copper. 

According to the vendor, bench-scale and pilot-scale tests have been performed in Canada and Asia. LIST is currently being used for a full-scale remediation of sediments contaminated with coal tar from a former manufacmred gas plant (MGP) site in Massachusetts. The technology is commercially available. 

Some caution may be needed when evaluating in situ technologies for the remediation of sediments. In situ treatment of sediments may be less cost-effective than ex situ methods because the treatment level for in situ methods is not uniform and in some cases project goals cannot be met throughout the site (D20043R, p. 6). 

The technology is commercially available and has been successfully applied for full-scale treatment and remediation of organic and inorganic contaminated material occurring at hazardous waste sites and within bays, harbors, and river areas. Bergmann USA was closed for business in 1998. However, the soil/sediment washing technology is still available from their parent company, Linatex, Inc. 

The MBI anaerobic polychlorinated biphenyl (PCB) dechlorinating granular consortia technology is an in situ bioremediation technology that uses anaerobic microbial consortia in granular form to remediate PCBs in contaminated soils and sediments. 

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). 

Natural attenuation, often called intrinsic remediation, intrinsic bioremediation, bioattenuation, or monitored natural attenuation (MNA) is an in situ treatment technology for soil, sediment, or groundwater. The technology has been used for full-scale remediation of sites contaminated with volatile organic compounds (VOCs), total petroleum hydrocarbons (TPH), chlorinated solvents, explosives, inorganics, and metals. 

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. 

Thermal desorption is a technology that physically separates volatile and some semivolatile contaminants from contaminated media. In thermal desorption, heated air is used to volatilize contaminants at temperatures below those used for incineration. There are both in situ and ex situ applications of the technology. Ex situ treatments typically are used to remediate soil, sediments, sludges, and filter cakes. In situ applications of the technology use injected steam, thermal blankets, or heat supplied by electrodes to volatilize contaminants, which are then removed using extraction wells. 

The Remediation Technologies, Inc. (RETEC), Thermatek thermal desorption system is an ex situ high-temperature treatment technology that treats soils, sediments, and sludges contaminated with volatile organic compounds (VOCs) and polychlorinated biphenyls (PCBs). The process uses a conventional Holo-Flite thermal desorption unit with RETEC s proprietary modifications, using an indirect heating source. 

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