Elemental iron (Fe0) used as a reducing agent in permeable reactive barriers and direct-push injection for the abiotic degradation of chlorinated solvents and reduction of hexavalent chromium. Available in granular, micro-, and nano-scale forms.
Zero-Valent Iron donates electrons to halogenated organics, cleaving carbon-halogen bonds and ultimately producing ethene, ethane, and chloride from chlorinated ethenes. It also reduces hexavalent chromium to the less mobile trivalent form. Granular ZVI is the standard medium for permeable reactive barriers; nanoscale ZVI (nZVI) is injected as a slurry for source-zone treatment where its high surface area and limited mobility favour rapid local reaction.
ZVI performance is governed by oxidation of the iron surface, fouling by carbonate and sulfide minerals, and competition between the contaminant and dissolved oxygen for electrons. Field longevity in permeable reactive barriers commonly exceeds 15 years for typical groundwater chemistries.
Also known as: ZVI, zero-valent iron, nano-ZVI, nZVI, micro-ZVI.
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.