A3.10.6.4 Thermal Options


Thermal treatment technologies are destruction and removal types of treatment.


Thermal Desorption

Thermal desorption technology is based on a physical separation system. The process desorbs (physically separates) organics from the soil without decomposition. Volatile and semi-volatile organics are removed from contaminated soil in thermal desorbers at 95-315°C for low-temperature thermal desorption (also called soil roasting), or at 315-340°C for high-temperature thermal desorption.

To transport the volatilised organics and water to the gas treatment system, the process uses an inert carrier gas. The gas treatment units can be condensers or carbon adsorption units, which will trap organic compounds for subsequent treatment or disposal. The units can also be afterburners or catalytic oxidizers that destroy the organic constituents.

The bed temperatures and residence times of the desorbers are designed to volatilise selected contaminants, not to oxidize them. Certain less volatile compounds may not be volatilised at low temperatures.



Pyrolysis means a chemical decomposition or change due to heating in the absence of oxygen (although it is not possible to achieve an atmosphere that is completely free from oxygen).



Incineration technology is intended to permanently destroy organic contaminants. Incineration is a complex system of interacting pieces of equipment and is not just a simple furnace. It is an integrated system of components for waste preparation, feeding, combustion and emissions control. Central to the system is the combustion chamber, or the incinerator.  There are four major types of incinerator: rotary kiln, fluidised bed, liquid injection, and infrared.