Contamination Remediation

If there are significant amounts of both volatile and nonvolatile contaminants, remediation may be achieved by a combination of Hquid and vapor extraction of the former, and bioremediation of the latter. This combination has been termed "bioslurping", where the act of pumping out the Hquid contaminant phase draws in air at other wells to stimulate aerobic degradation (20). Such bioremediation requites that there be enough nutrients to allow microbial growth, and fertilizer nutrients are frequendy added at the air injection wells. Bioslurping has had a number of weU-documented successes. 

U.S. EPA, Permeable Reactive Barrier Technologies for Contaminant Remediation, EPA/600/R-98/125, Office of Research and Development, United States Environmental Protection Agency, Washington, DC, September 1998. 

In some cases, reductants are injected into aquifers to remove Cr(VI) from solution (Blowes 2002). Reduction of Cr(VI) to Cr(III) is thus a central issue in approaches to Cr(VI) contaminant remediation. 

If there are significant amounts of both volatile and nonvolatile contaminants, remediation may be achieved by a combination of liquid and vapor extraction of the former, and bioremediation of the latter. This combination has been termed bioslurping . 

Source U.S. EPA, Remediation Technologies Development Forum (RTDF) Permeable Reactive Barrier Technologies for Contamination Remediation, EPA/ 600/R-98/125, U.S. EPA, Washington, D.C., 1998. 

While waste management attempts to prevent site contamination, remediation deals with sites that have already been contaminated. Remediation refers to the restoration of a site through the treatment of its... 

Such specificity is often possible with systems engineered for contaminant remediation. However, natural systems frequently involve complex mixtures of redox-active substances that cannot be characterized readily. The characterization of redox conditions in complex environmental media is a long-standing challenge to environmental scientists that continues to be an active area of research (Section 3.3). 

The best opportunities for predicting redox transformations come from engineered systems where a known oxidant is added to achieve contaminant remediation. Well-documented examples include the use of ozone (Example 2.2.1.1) and chlorine dioxide (e.g., 41, 42) in... 

A similar situation applies for reduced forms of iron (35, 36, 39, 65, 75, 76). As with oxidations, some of the best opportunities for reliably estimating rates of redox transformations are afforded by engineered systems where a reductant of known composition and quantity is added to achieve contaminant remediation. In addition to zero-valent iron, other chemical methods for reduction of contaminants involve dithionite (77-79) and electrolysis (where, in effect, electrons are added directly, e.g., 80, 81). 

Tratnyek PG, Johnson TL, Schattauer A. Interfacial phenomena affecting contaminant remediation with zero-valent iron metal. Emerging Technologies in Hazardous Waste Management VII. Atlanta, GA American Chemical Society, 1995 589-592. 

Benomyi/Carbendazim Carbofuran Chlorothalonil Chlorpyrifos Cyanazine Cyclodienes Methomyl Metolachlor Procymidone Simazine Spinosad Triclopyr DDT Lindane Toxaphene Triazines Industrial contaminants/remediation BTEX PAHs, cPAHs PCBs PCP TPH TNT RDX... 

Ground Water and Soil Contamination Remediation Toward Compatible Science, Policy, and Public Perception... 

D.L. Barry, The Millennium Dome (Greenwich Millennium Experience Site) Contamination Remediation, Land Contam. Reclam., 1999, 7, 177-190. 

All studies were conducted at very high initial MTBE concentrations (between 10 to 900 mg/L) compared to concentrations typically found in ground and surface waters apart from contaminated remediation sites. In the concentration range studied, however, no influence of the initial MTBE concentration on the MTBE flux through the membrane could be observed [ 130]. 

Each risk-based remedial action objective for an exposure pathway will typically include numeric remedial action levels for each contaminant. Remedial action levels may also be developed for non-risk remedial action objectives such as resource protection standards. The non-risk remedial action levels may include thickness or mobility criteria for non-aqueous phase liquids (NAPL). 

Perhaps the most detailed accounts of field studies presently available are those conducted by Lagemem and coworkers [83,84]. Table 3 contains a summary of the sites and the metal contaminants remediated. The anode and cathode housings are interconnected in this process and form two separate circulation systems filled with different chemical solutions, details of which are not provided in the publications. However, the extent of remediation of many of the metal contaminants tested Is quite high. These studies demonstrate that electrochemical processing of soils is a viable and practical technology. 

Electrically induced migration of ions and water is a proven method of externally forced mass transport in clay soils for contaminant remediation purposes (Pamukcu and Wittle, 1992 Acar and Alshawabkeh, 1993,1996 Lageman, 1993 Probstein and... 

US EPA. (1998). Permeable Reactive Barrier Technologies for Contaminant Remediation. 

Subsurface Contamination Remediation Accomplishments of the Environmental Management... 

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