Ex-Situ Chemical Oxidation

Description

Ex-situ chemical oxidation involves mixing an oxidizing compound with contaminated groundwater in a vessel. The oxidizing compound can be a solution (e.g., sodium hypochlorite in water) or a gas (e.g., ozone). The oxidizing agents most commonly used for the chemical treatment of organic contaminants are ozone, hydrogen peroxide, hypochlorites, chlorine, and chlorine dioxide. The treatment chemicals typically mineralize most organic compounds to carbon dioxide, water, and salts. The main advantage of ex-situ chemical oxidation as opposed to in-situ chemical oxidation is that it allows sufficient time for oxidation to occur in a controlled environment.

Limitations and Concerns

Incomplete oxidation or formation of intermediate contaminants may occur depending upon the contaminants and oxidizing agents used.

The process is not cost-effective for high contaminant concentrations because of the large amounts of oxidizing agent required.

When chlorine is used for oxidation, undesirable substitution products such as chloromethanes can form.

Chemicals other than contaminants may consume oxidizing agents, increasing treatment cost and creatings the potential for forming undesirable byproducts.

Applicability

This technology can be used to treat halogenated and nonhalogenated volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs). It has been experimented with polychlorinated biphenyls (PCBs) and ordnance compounds.

Technology Development Status

This is a commercially available technology.

Web Links

http://enviro.nfesc.navy.mil/erb/restoration/technologies/remed/phys_chem/phc-06.asp

Other Resources and Demonstrations

See In-Situ Chemical Oxidation.