Activated Persulfate
Activated persulfate is an established technology for the oxidation of a wide range of organic compounds, though the efficacy of treatment may depend upon the activator used. Persulfate alone is a relatively strong oxidant, but activation generates the sulfate radical, which is an even stronger oxidant. Common activators include heat, divalent metals, chelated metals (e.g. iron EDTA), hydrogen peroxide, calcium peroxide, and high pH (pH > 10.5). Persulfate decomposes to generate sulfuric acid. The change in sulfate concentration and the effect on pH depend upon the amount of persulfate used and the buffering ability of site soil and groundwater, among other factors. Other potential secondary effects include oxidation of soil chromium to Cr(VI) and mobilization of metals due to changes in pH. The magnitude, duration, and significance of any such affects are site specific.

Catalyzed Hydrogen Peroxide (aka Fenton’s Reagent)
Catalyzed hydrogen peroxide (CHP) is a mixture of hydrogen peroxide (H2O2) and a catalyst that generates radicals, which are stronger oxidants than H2O2 alone. If the catalyst is acidified ferrous iron, the mixture is known as Fenton’s Reagent. If the catalyst is used at near-neutral pH, the mixture is sometimes referred to as modified Fenton’s Reagent. Catalysts that may be used at near-neutral pH are often proprietary and include chelated iron (application of which may be covered by patents held by ISOTEC, VTX, or nano-scale ZVI. CHP decomposes to oxygen and water (1L of 1% H2O2 produces approximately 3L of oxygen gas). The reaction is exothermic, though the temperature increase may be negligible or significant depending upon the concentration of H2O2, the rate at which it decomposes, and other factors. Contaminants can be completely oxidized to carbon dioxide and water.

Klozur CR
Klozur CR is a form of activated persulfate. It is a pre-blended mixture of sodium persulfate and PermeOx Plus, which enables alkaline activation of persulfate as well as formation of dissolved oxygen. Klozur CR may be purchased from the manufacturer, FMC, or from an FMC distributor such as ChemRem.

Ozone
Ozone gas is a strong oxidant that can react with a wide range of organic compounds, potentially converting them to carbon dioxide and water; ozone itself decomposes to oxygen gas. Possible secondary effects of in situ treatment using ozone include formation of Cr(VI) from soil chromium and formation of bromate from naturally occurring bromide. The magnitude, duration and significance of secondary effects are site specific.

Ozone + Hydrogen Peroxide
Ozone + hydrogen peroxide is an advanced oxidation process (AOP) that may be more effective toward some COCs than ozone alone (especially when used ex situ) because it can generate the hydroxyl radical, an even stronger oxidant than ozone or peroxide alone. The presence of hydrogen peroxide may also reduce the likelihood of Cr(VI) and bromate formation.

Permanganate
Permanganate is a moderately strong oxidizing agent that is available as solid potassium permanganate (KMnO4) or liquid sodium permanganate (NaMnO4). It is most commonly used to oxidize chlorinated ethenes (PCE, TCE, DCE and VC), but has also been shown to react with pentachlorophenol and the pesticides Aldrin and Dieldrin. Permanganate reacts with some natural organic matter and other oxidizable species in soil, and in many cases, the soil oxidant demand (SOD) rather than the COC mass, determines the amount of permanganate required at a site. The most common side effect of in situ treatment using permanganate is oxidation of soil chromium to Cr(VI). The amount of Cr(VI) formed and its ability to attenuate are site-specific.

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