Strong chemical oxidant used in ISCO, supplied as sodium persulfate. When activated by heat, high pH, ferrous iron, or hydrogen peroxide, the persulfate ion generates sulfate radicals capable of destroying a broad contaminant suite including benzene, 1,4-dioxane, and chlorinated solvents.
The persulfate ion (S2O8 2-) is supplied as sodium persulfate (Na2S2O8). On its own, persulfate is a moderate oxidant; activation by alkaline pH, ferrous iron, heat, or hydrogen peroxide generates sulfate radicals (SO4-.) with reactivity comparable to hydroxyl radicals but with longer half-life and broader pH operating range.
Activated persulfate is the ISCO oxidant of choice for benzene-impacted groundwater, 1,4-dioxane (where permanganate is ineffective), MTBE, and mixed chlorinated solvent and petroleum hydrocarbon sites. Persistence in the subsurface is intermediate between permanganate and Fenton's, on the order of days to weeks depending on activator and natural oxidant demand.
Activation method is the design variable that decides success. Alkaline-activated persulfate performs across a wide contaminant suite at near-neutral aquifer conditions. Heat activation pairs naturally with in-situ thermal remedies, where residual warmth from thermal treatment activates persulfate injected as a polishing step. Iron activation is economical but consumes oxidant through side reactions in iron-rich soils. Bench testing against actual site groundwater is standard practice before full-scale dosing.
Also known as: persulfate, persulfate ion, sodium persulfate, activated persulfate, S2O8.
The persulfate ion (S2O8 2-) is a strong oxidizing agent supplied for remediation as sodium persulfate. When activated by heat, high pH, iron, or peroxide it generates sulfate radicals that destroy contaminants including benzene, 1,4-dioxane, MTBE, and chlorinated solvents in groundwater.
Activated persulfate is an in-situ chemical oxidation (ISCO) reagent injected into contaminated soil and groundwater. It is the preferred oxidant for benzene plumes, 1,4-dioxane, and mixed petroleum and solvent sites because its sulfate radicals persist for days to weeks, longer than Fenton's reagent.
Four ways: alkaline activation (raising pH above roughly 10.5), heat activation (above about 40 degrees Celsius), ferrous iron activation, and hydrogen peroxide activation. Each produces sulfate radicals; the choice depends on site pH, temperature, soil chemistry, and target contaminants.
It depends on the contaminants. Permanganate is excellent for chlorinated ethenes (TCE, PCE) but cannot touch benzene or 1,4-dioxane. Persulfate, once activated, oxidizes both petroleum compounds and solvents, making it the better choice for mixed plumes. Many sites use them in sequence.
In-Situ Chemical Oxidation (ISCO): treatment approach
In-situ chemical oxidation: injection of a chemical oxidant — permanganate, persulfate, or Fenton's reagent — directly into contaminated soil or groundwater to destroy dissolved-phase organic contaminants without excavation.
An ex-situ soil treatment process that heats contaminated soil to volatilize and separate organic contaminants from the soil matrix, after which the liberated vapors are captured and treated, usually in a high-temperature oxidizer.
A thermal desorption configuration where the heat source contacts the soil directly inside the rotary unit, delivering high heat-transfer efficiency and supporting higher treatment temperatures.
A thermal desorption configuration where heat is conducted through the wall of the treatment vessel without combustion gases contacting the soil, producing a concentrated, lower-volume vapor stream suitable for condensation and recovery.
Treatment that heats contaminated soil and groundwater in place, typically with electrical resistance, thermal conduction, or steam injection, to volatilize and recover contaminants without excavation. Used where excavation is impractical or where the contaminant zone sits beneath active infrastructure.