Chemical Oxidation of Soils
Background
Reduction/oxidation (Redox) reactions chemically convert hazardous contaminants in soils to non-hazardous or less toxic compounds. Transfer of electrons from one compound to another results in oxidizing one compound and reducing the other. The oxidizing agents most commonly used for treating hazardous contaminants include ozone, hydrogen peroxide, hypochlorites, chlorine, and chlorine dioxide. Chemical redox is a full-scale, well established technology used for wastewater treatment and more frequently for contaminant treatment in soils [1,2,3].
Applicability
Chemical redox is applicable to inorganic contaminants in soil and waste water. This technology has less of an effect on contaminants, such as non-halogenated volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), fuel hydrocarbons, and pesticides [2,3].
Limitations
Factors that may limit the applicability and effectiveness of the process include: (1) intermediate contaminants may form due to incomplete oxidation; (2) the cost is high for high contaminant concentrations due to the use of excessive amounts of oxidizing agents; and (3) oil and grease in the media would negatively affect the treatment efficiency [2,3].
Performance
Not available.
Data Requirements
Treatability tests should be conducted to identify parameters such as water, alkaline metals, and humus content in the soils. The presence of multiple phases and the total organic halides that could affect processing time and cost must be determined [1,2].
Cost
The typical cost for this type of in situ bioremediation technology ranges from $190 to $660 per cubic meter [3].
Status of Technology
Chemical redox for the disinfection of drinking water and wastewater is a well-established technology. This full-scale process also is used to treat cyanide and chromium wastes. Soil is now being treated using enhanced systems [3].
References
1. Cookson, J.T. Jr., 1995, Bioremediation Engineering Design and Application, McGraw-Hill, Inc., New York, NY.2. EPA, 1991, Chemical Oxidation Treatment Engineering Bulletin, EPA, OERR and ORD, Washington, DC, EPA/530/2-91/025.
3. Office of Research and Development, EPA, ATTIC Downloadable Documents, available at http://www.epa.gov/bbsnrmrl/attic/documents.html.