In-situ technology that applies a vacuum to extraction wells screened in the vadose zone, drawing soil gas and entrained VOCs to the surface for treatment. The dominant remediation method for VOC source areas above the water table and a near-universal complement to in-situ thermal treatment.
Soil Vapour Extraction induces airflow through the unsaturated zone by pulling a vacuum on extraction wells. Volatile and some semi-volatile organic compounds partition from soil and pore water into the moving air stream and are removed for above-ground treatment, typically by granular activated carbon, thermal oxidation, or catalytic oxidation. SVE is most effective in permeable, dry soils with VOCs of Henry's Law constant above roughly 0.01.
Performance is governed by air permeability, contaminant volatility, and mass-transfer limitations from low-permeability zones. SVE rates typically decline asymptotically as the readily volatile mass is removed, and rebound after shutdown is common. SVE is the dominant vapour-capture system paired with ERH, TCH, and SEE in in-situ thermal projects.
Also known as: SVE, soil vapor extraction, vacuum extraction.
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.