Soil vapour extraction (SVE) is an effective remediation technology for soil. "Multi Phase Extraction" (MPE) is also an effective remediation technology when soil and groundwater are to be remediated coincidentally. SVE and MPE utilize different technologies to treat the off-gas volatile organic compounds (VOCs) generated after vacuum removal of air and vapours (and VOCs) from the subsurface and include granular activated carbon (most commonly used historically), thermal and/or catalytic oxidation and vapour condensation. Generally, carbon is used for low (<500ppmV) VOC concentration vapour streams, oxidation is used for moderate (up to 4,000 ppmV) VOC concentration streams, and vapour condensation is used for high (>4,000 ppmV) VOC concentration vapour streams. Below is a brief summary of each technology.

Granular activated carbon (GAC) is used as a filter for air or water. It is commonly used to filter tap water in household sinks. GAC is a highly porous adsorbent material, produced by heating organic matter, such as coal, wood and coconut shell, in the absence of air, which is then crushed into granules. Activated carbon is positively charged and therefore able to remove negative ions from the water such as organic ions, ozone, chlorine, fluorides and dissolved organic solutes by adsorption onto the activated carbon. The activated carbon must be replaced periodically as it may become saturated and unable to adsorb (i.e. reduced absorption efficiency with loading). Activated carbon is not effective in removing heavy metals.

Thermal oxidation (or incineration) can also be an effective remediation technology. This approach is somewhat controversial because of the risks of dioxins released in the atmosphere through the exhaust gases or effluent off-gas. Controlled, high temperature incineration with filtering of exhaust gases however should not pose any risks. Two different technologies can be employed to oxidize the contaminants of an extracted vapour stream. The selection of either thermal or catalytic depends on the type and concentration in parts per million by volume of constituent in the vapour stream. Thermal oxidation is more useful for higher concentration (~4,000 ppmV) influent vapour streams (which require less natural gas usage) than catalytic oxidation at ~2,000 ppmV.

1. Thermal oxidation which uses a system that acts as a furnace and maintains temperatures ranging from 1350°F to 1500°F (730°C-815°C).
2. Catalytic oxidation which uses a catalyst on a support to facilitate a lower temperature oxidation. This system usually maintains temperatures ranging from 600°F to 800°F (315°C-430°C).

Vapour condensation is the most effective off-gas treatment technology for high (>4,000 ppmV) VOC concentration vapour streams. The process involves cryogenically cooling the vapour stream to below 40 degrees C such that the VOCs condensate out of the vapour stream and into liquid form where it is collected in steel containers. The liquid form of the VOCs is referred to as dense non-aqueous phase liquids (DNAPL) when the source of the liquid consists predominantly of solvents or light non-aqueous phase liquids (LNAPL) when the source of the liquid consists predominantly of petroleum or fuel products. This recovered chemical can then be reused or recycled in a more environmentally sustainable or green manner than the alternatives described above. This technology is also known as cryogenic cooling and compression (C3-Technology).