Sodium/Potassium Permanganate

As an oxidizer, permanganate has a unique affinity for destroying organic compounds that contain carbon-carbon double bonds. The permanganate ion is strongly attracted to the negative charge associated with electrons in the pi-cloud of carbon-carbon double bonds of chlorinated alkenes such as PCE, TCE, DCE and VC. The permanganate ion borrows electron density from the pi-bond, which disturbs the carbon-carbon double bond, thus forming a bridged oxygen compound known as the hypomanganate diester. This intermediate product is unstable and further reacts by a number of mechanisms including hydroxylation, hydrolysis or cleavage. The final oxidation product is carbon dioxide, chloride salt and manganese dioxide.

Although the reaction of the permanganate ion with contaminants is well understood, these reactions have not been commonly used for in-situ remediation due to complications that result from manganese dioxide which is formed as a precipitate of the reaction. Plugging of the soil matrix with manganese dioxide has been observed when permanganate salts are passively injected into the soils through injection wells or points. This plugging results in poor contact of the oxidizing agent with the contaminants of concern, resulting in inefficient treatment due to channeling of the oxidant in the subsurface. Injuries to workers have occurred from the pressure build-up caused by injection techniques. Injection techniques have also been found to be ineffective in some cases where globules of contamination exist in the subsurface because the globules become encrusted with manganese dioxide precipitate, thus preventing further oxidant contact. Finally, the manganese dioxide precipitates that form from the reaction are unstable as they are readily reduced by chemical or biological in-situ processes to form soluble divalent manganese ions.

Tetrachloroethylene is the most stable derivative of the chlorinated ethanes and ethylenes that contaminate groundwater. Conventional pump and treat methods have had limited success in remediating sites were PCE, TCE and other dense non-aqueous-phase liquids (DNAPL’s) are present. Instead, in-situ oxidation with sodium and potassium permanganate has emerged as one of the most effective methods for treating these contaminants.

Although other oxidants also are capable of oxidizing PCE, they rely on intermediate hydroxyl radicals, or advanced oxidation processes (AOP’s), as part of their reaction scheme. AOP’s tend to react rapidly with radical scavengers, such as carbonate and bicarbonate, which are present in many natural waters. The reaction with AOP’s and radical scavengers typically increases oxidant requirements and, therefore diminishes the AOP’s effectiveness in oxidizing the contaminant. As a result of Permanganate following a different reaction scheme, it can react with unsaturated compounds including chlorinated ethylenes, through direct oxygen transfer, rather than relying on radicals.

Critical to the success of the proposed remedial technologies is the successful delivery of the various materials to the targeted groundwater and soils.

Fenton’s Reagent

The Fenton’s Reagent Oxidation Process is an innovative in-situ and/or ex-situ treatment technology for remediating soil and groundwater contaminated with organic compounds. Remediation occurs by injecting a strong chemical oxidizer, such as a reagent mixture consisting of hydrogen peroxide, ferrous iron (a catalyst) and sulfuric acid (an optimum pH adjuster). The principal active component of the reaction is the hydroxyl free radical (OH), which is produced by catalytic chemical reaction between hydrogen peroxide and ferrous iron under an optimum pH condition. The hydroxyl free radical produced cleaves and oxidizes organic compounds non-selectively that result in forming successively smaller chained hydrocarbon compounds. The intermediate compounds formed are generally mono- and di-carboxyl acids, which are non-hazardous, naturally occurring substances easily oxidized to carbon dioxide and water (a complete mineralization) during subsequent sequential reactions. The cleaving of organic compounds does not and will not produce any volatile organic compounds that can be released to the atmosphere jeopardizing the environment quality.

OZONE

Ozone is a colorless gas found naturally in outside atmospheric air. In these natural quantities, it is found to be concentrations from 0.02 ppm to 0.05 ppm (parts per million) of volume. Ozone consists of three atoms of oxygen, sometimes referred to as triatomic oxygen. It is relatively unstable, decaying very rapidly by reverting back to oxygen.

As a very powerful oxidizer, it chemically breaks down the bonds which hold together Volatile Organic Compounds (VOC's) and reduces them to oxygen, leaving no chemical residue.